From 39f852e656a10cc5558148fb31c4f93f4c455d6f Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 6 Jun 2021 22:13:15 +0800 Subject: [PATCH 001/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200222.=E5=AE=8C?= =?UTF-8?q?=E5=85=A8=E4=BA=8C=E5=8F=89=E6=A0=91=E7=9A=84=E8=8A=82=E7=82=B9?= =?UTF-8?q?=E4=B8=AA=E6=95=B0=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0222.完全二叉树的节点个数 go版本 --- .../0222.完全二叉树的节点个数.md | 29 +++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/problems/0222.完全二叉树的节点个数.md b/problems/0222.完全二叉树的节点个数.md index 91e24247..998e22f3 100644 --- a/problems/0222.完全二叉树的节点个数.md +++ b/problems/0222.完全二叉树的节点个数.md @@ -308,6 +308,35 @@ class Solution: Go： +递归版本 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +//本题直接就是求有多少个节点，无脑存进数组算长度就行了。 +func countNodes(root *TreeNode) int { + if root == nil { + return 0 + } + res := 1 + if root.Right != nil { + res += countNodes(root.Right) + } + if root.Left != nil { + res += countNodes(root.Left) + } + return res +} +``` + + + JavaScript: 递归版本 From c7c3d8febf477054cefd6b243d07dc3cb512ad00 Mon Sep 17 00:00:00 2001 From: ChrisLin Date: Sun, 6 Jun 2021 22:19:11 +0800 Subject: [PATCH 002/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00746.=E4=BD=BF?= =?UTF-8?q?=E7=94=A8=E6=9C=80=E5=B0=8F=E8=8A=B1=E8=B4=B9=E7=88=AC=E6=A5=BC?= =?UTF-8?q?JavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0746.使用最小花费爬楼梯.md | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/problems/0746.使用最小花费爬楼梯.md b/problems/0746.使用最小花费爬楼梯.md index 1e8e8038..4238a389 100644 --- a/problems/0746.使用最小花费爬楼梯.md +++ b/problems/0746.使用最小花费爬楼梯.md @@ -255,7 +255,18 @@ func min(a, b int) int { } ``` - +Javascript： +```Javascript +var minCostClimbingStairs = function(cost) { + const dp = [ cost[0], cost[1] ] + + for (let i = 2; i < cost.length; ++i) { + dp[i] = Math.min(dp[i -1] + cost[i], dp[i - 2] + cost[i]) + } + + return Math.min(dp[cost.length - 1], dp[cost.length - 2]) +}; +``` ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From 05f0c7ae93345d65986edc6e62ea8afb7bfd47c1 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Sun, 6 Jun 2021 18:32:53 -0700 Subject: [PATCH 003/122] =?UTF-8?q?Update=20=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=E4=B8=AD=E9=80=92=E5=BD=92=E5=B8=A6=E7=9D=80=E5=9B=9E=E6=BA=AF?= =?UTF-8?q?.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/二叉树中递归带着回溯.md | 77 ++++++++++++++++++++++ 1 file changed, 77 insertions(+) diff --git a/problems/二叉树中递归带着回溯.md b/problems/二叉树中递归带着回溯.md index 2adb826c..aede1831 100644 --- a/problems/二叉树中递归带着回溯.md +++ b/problems/二叉树中递归带着回溯.md @@ -257,6 +257,83 @@ Java： Python： +100.相同的树 +> 递归法 +```python +class Solution: + def isSameTree(self, p: TreeNode, q: TreeNode) -> bool: + return self.compare(p, q) + + def compare(self, tree1, tree2): + if not tree1 and tree2: + return False + elif tree1 and not tree2: + return False + elif not tree1 and not tree2: + return True + elif tree1.val != tree2.val: #注意这里我没有使用else + return False + + #此时就是：左右节点都不为空，且数值相同的情况 + #此时才做递归，做下一层的判断 + compareLeft = self.compare(tree1.left, tree2.left) #左子树：左、 右子树：左 + compareRight = self.compare(tree1.right, tree2.right) #左子树：右、 右子树：右 + isSame = compareLeft and compareRight #左子树：中、 右子树：中（逻辑处理） + return isSame +``` + +257.二叉的所有路径 +> 递归中隐藏着回溯 +```python +class Solution: + def binaryTreePaths(self, root: TreeNode) -> List[str]: + result = [] + path = [] + if not root: + return result + self.traversal(root, path, result) + return result + + def traversal(self, cur, path, result): + path.append(cur.val) + #这才到了叶子节点 + if not cur.left and not cur.right: + sPath = "" + for i in range(len(path)-1): + sPath += str(path[i]) + sPath += "->" + sPath += str(path[len(path)-1]) + result.append(sPath) + return + if cur.left: + self.traversal(cur.left, path, result) + path.pop() #回溯 + if cur.right: + self.traversal(cur.right, path, result) + path.pop() #回溯 +``` + +> 精简版 +```python +class Solution: + def binaryTreePaths(self, root: TreeNode) -> List[str]: + result = [] + path = "" + if not root: + return result + self.traversal(root, path, result) + return result + + def traversal(self, cur, path, result): + path += str(cur.val) #中 + if not cur.left and not cur.right: + result.append(path) + return + if cur.left: + self.traversal(cur.left, path+"->", result) #左 回溯就隐藏在这里 + if cur.right: + self.traversal(cur.right, path+"->", result) #右 回溯就隐藏在这里 +``` Go： From d268469c225421e6424954ba5c7dad0cc357332f Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Sun, 6 Jun 2021 20:23:45 -0700 Subject: [PATCH 004/122] =?UTF-8?q?Update=200198.=E6=89=93=E5=AE=B6?= =?UTF-8?q?=E5=8A=AB=E8=88=8D.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0198.打家劫舍.md | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/problems/0198.打家劫舍.md b/problems/0198.打家劫舍.md index 8b46a784..f49857bb 100644 --- a/problems/0198.打家劫舍.md +++ b/problems/0198.打家劫舍.md @@ -131,7 +131,20 @@ class Solution { ``` Python： - +```python +class Solution: + def rob(self, nums: List[int]) -> int: + if len(nums) == 0: + return 0 + if len(nums) == 1: + return nums[0] + dp = [0] * len(nums) + dp[0] = nums[0] + dp[1] = max(nums[0], nums[1]) + for i in range(2, len(nums)): + dp[i] = max(dp[i-2]+nums[i], dp[i-1]) + return dp[-1] +``` Go： ```Go From 74d061366602ec1f10b42ce7e9bc0e0406bb4d5f Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Sun, 6 Jun 2021 21:02:20 -0700 Subject: [PATCH 005/122] =?UTF-8?q?Update=200337.=E6=89=93=E5=AE=B6?= =?UTF-8?q?=E5=8A=AB=E8=88=8DIII.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0337.打家劫舍III.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/problems/0337.打家劫舍III.md b/problems/0337.打家劫舍III.md index 58d0e640..0a4b752b 100644 --- a/problems/0337.打家劫舍III.md +++ b/problems/0337.打家劫舍III.md @@ -287,6 +287,25 @@ class Solution { Python： +> 动态规划 +```python +class Solution: + def rob(self, root: TreeNode) -> int: + result = self.robTree(root) + return max(result[0], result[1]) + + #长度为2的数组，0：不偷，1：偷 + def robTree(self, cur): + if not cur: + return (0, 0) #这里返回tuple, 也可以返回list + left = self.robTree(cur.left) + right = self.robTree(cur.right) + #偷cur + val1 = cur.val + left[0] + right[0] + #不偷cur + val2 = max(left[0], left[1]) + max(right[0], right[1]) + return (val2, val1) +``` Go： From 0913f488a401d5102a347852e1eecd3b30836f1f Mon Sep 17 00:00:00 2001 From: zhangzw Date: Mon, 7 Jun 2021 12:03:16 +0800 Subject: [PATCH 006/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-1=20Go?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-1.md | 33 ++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index a78d9232..de4508ad 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -273,7 +273,40 @@ Python： Go： +```go +func test_2_wei_bag_problem1(weight, value []int, bagWeight int) int { + // 定义dp数组 + dp := make([][]int, len(weight)) + for i, _ := range dp { + dp[i] = make([]int, bagWeight+1) + } + // 初始化 + for j := bagWeight; j >= weight[0]; j-- { + dp[0][j] = dp[0][j-weight[0]] + value[0] + } + // 递推公式 + for i := 1; i < len(weight); i++ { + //正序,也可以倒序 + for j := weight[i];j<= bagWeight ; j++ { + dp[i][j] = max(dp[i-1][j], dp[i-1][j-weight[i]]+value[i]) + } + } + return dp[len(weight)-1][bagWeight] +} +func max(a,b int) int { + if a > b { + return a + } + return b +} + +func main() { + weight := []int{1,3,4} + value := []int{15,20,30} + test_2_wei_bag_problem1(weight,value,4) +} +``` ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From 7fe87c16d93eb2b2fdaeaf0cc53a1499135d0e3a Mon Sep 17 00:00:00 2001 From: zhangzw Date: Mon, 7 Jun 2021 12:03:53 +0800 Subject: [PATCH 007/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2=20Go?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 29 ++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index e831d88f..1d3f8b03 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -219,7 +219,36 @@ Python： Go： +```go +func test_1_wei_bag_problem(weight, value []int, bagWeight int) int { + // 定义 and 初始化 + dp := make([]int,bagWeight+1) + // 递推顺序 + for i := 0 ;i < len(weight) ; i++ { + // 这里必须倒序,区别二维,因为二维dp保存了i的状态 + for j:= bagWeight; j >= weight[i] ; j-- { + // 递推公式 + dp[j] = max(dp[j], dp[j-weight[i]]+value[i]) + } + } + //fmt.Println(dp) + return dp[bagWeight] +} +func max(a,b int) int { + if a > b { + return a + } + return b +} + + +func main() { + weight := []int{1,3,4} + value := []int{15,20,30} + test_1_wei_bag_problem(weight,value,4) +} +``` From 23e979a862a24327aa9ec45211c34492c613e762 Mon Sep 17 00:00:00 2001 From: lichuanming <1465802096@qq.com> Date: Mon, 7 Jun 2021 15:40:56 +0800 Subject: [PATCH 008/122] =?UTF-8?q?0674=20java=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0674.最长连续递增序列.md | 26 ++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0674.最长连续递增序列.md b/problems/0674.最长连续递增序列.md index 46413d98..636ee0cc 100644 --- a/problems/0674.最长连续递增序列.md +++ b/problems/0674.最长连续递增序列.md @@ -156,7 +156,31 @@ public: Java： - +```java + /** + * 1.dp[i] 代表当前下表最大连续值 + * 2.递推公式 if（nums[i+1]>nums[i]） dp[i+1] = dp[i]+1 + * 3.初始化 都为1 + * 4.遍历方向，从其那往后 + * 5.结果推导 。。。。 + * @param nums + * @return + */ + public static int findLengthOfLCIS(int[] nums) { + int[] dp = new int[nums.length]; + for (int i = 0; i < dp.length; i++) { + dp[i] = 1; + } + int res = 1; + for (int i = 0; i < nums.length - 1; i++) { + if (nums[i + 1] > nums[i]) { + dp[i + 1] = dp[i] + 1; + } + res = res > dp[i + 1] ? res : dp[i + 1]; + } + return res; + } +``` Python： From 2499b611a5129717fa99e10a89daa170e7084f99 Mon Sep 17 00:00:00 2001 From: nmydt <62681228+nmydt@users.noreply.github.com> Date: Mon, 7 Jun 2021 16:44:12 +0800 Subject: [PATCH 009/122] =?UTF-8?q?Update=200530.=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=90=9C=E7=B4=A2=E6=A0=91=E7=9A=84=E6=9C=80=E5=B0=8F=E7=BB=9D?= =?UTF-8?q?=E5=AF=B9=E5=B7=AE.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0530.二叉搜索树的最小绝对差.md | 25 ++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/problems/0530.二叉搜索树的最小绝对差.md b/problems/0530.二叉搜索树的最小绝对差.md index 143bd053..03c48d9c 100644 --- a/problems/0530.二叉搜索树的最小绝对差.md +++ b/problems/0530.二叉搜索树的最小绝对差.md @@ -151,7 +151,30 @@ public: Java： - +递归 +```java +class Solution { + TreeNode pre;// 记录上一个遍历的结点 + int result = Integer.MAX_VALUE; + public int getMinimumDifference(TreeNode root) { + if(root==null)return 0; + traversal(root); + return result; + } + public void traversal(TreeNode root){ + if(root==null)return; + //左 + traversal(root.left); + //中 + if(pre!=null){ + result = Math.min(result,root.val-pre.val); + } + pre = root; + //右 + traversal(root.right); + } +} +``` ```Java class Solution { TreeNode pre;// 记录上一个遍历的结点 From 13537833ada6dedea5f7bb91766e6ecd1b9b172a Mon Sep 17 00:00:00 2001 From: zhangzw Date: Mon, 7 Jun 2021 16:46:29 +0800 Subject: [PATCH 010/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00474.=E4=B8=80?= =?UTF-8?q?=E5=92=8C=E9=9B=B6=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0474.一和零.md | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/problems/0474.一和零.md b/problems/0474.一和零.md index d60faa98..fd925f76 100644 --- a/problems/0474.一和零.md +++ b/problems/0474.一和零.md @@ -206,7 +206,43 @@ class Solution: ``` Go： +```go +func findMaxForm(strs []string, m int, n int) int { + // 定义数组 + dp := make([][]int, m+1) + for i,_ := range dp { + dp[i] = make([]int, n+1 ) + } + // 遍历 + for i:=0;i= zeroNum;j-- { + for k:=n ; k >= oneNum;k-- { + // 推导公式 + dp[j][k] = max(dp[j][k],dp[j-zeroNum][k-oneNum]+1) + } + } + //fmt.Println(dp) + } + return dp[m][n] +} +func max(a,b int) int { + if a > b { + return a + } + return b +} +``` From 55f48dc2718afa8886fcdc27a616231693b27480 Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Mon, 7 Jun 2021 21:14:00 +0800 Subject: [PATCH 011/122] =?UTF-8?q?0860.=E6=9F=A0=E6=AA=AC=E6=B0=B4?= =?UTF-8?q?=E6=89=BE=E9=9B=B6.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0860.柠檬水找零.md | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/problems/0860.柠檬水找零.md b/problems/0860.柠檬水找零.md index faee2e56..1a5634b5 100644 --- a/problems/0860.柠檬水找零.md +++ b/problems/0860.柠檬水找零.md @@ -184,7 +184,41 @@ class Solution: Go： +Javascript: +```Javascript +var lemonadeChange = function(bills) { + let fiveCount = 0 + let tenCount = 0 + let twentyCount = 0 + for(let i = 0; i < bills.length; i++) { + let bill = bills[i] + if(bill === 5) { + fiveCount += 1 + } else if (bill === 10) { + if(fiveCount > 0) { + fiveCount -=1 + tenCount += 1 + } else { + return false + } + } else { + if(tenCount > 0 && fiveCount > 0) { + twentyCount += 1 + tenCount -= 1 + fiveCount -= 1 + } else if(fiveCount >= 3) { + twentyCount += 1 + fiveCount -= 3 + } else { + return false + } + } + } + return true +}; + +``` ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From 622a5e233b9935dd95dc7b1bca8d2afd08b15376 Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Mon, 7 Jun 2021 21:14:42 +0800 Subject: [PATCH 012/122] =?UTF-8?q?0860.=E6=9F=A0=E6=AA=AC=E6=B0=B4?= =?UTF-8?q?=E6=89=BE=E9=9B=B6.md=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0860.柠檬水找零.md | 3 --- 1 file changed, 3 deletions(-) diff --git a/problems/0860.柠檬水找零.md b/problems/0860.柠檬水找零.md index 1a5634b5..a18c008d 100644 --- a/problems/0860.柠檬水找零.md +++ b/problems/0860.柠檬水找零.md @@ -189,7 +189,6 @@ Javascript: var lemonadeChange = function(bills) { let fiveCount = 0 let tenCount = 0 - let twentyCount = 0 for(let i = 0; i < bills.length; i++) { let bill = bills[i] @@ -204,11 +203,9 @@ var lemonadeChange = function(bills) { } } else { if(tenCount > 0 && fiveCount > 0) { - twentyCount += 1 tenCount -= 1 fiveCount -= 1 } else if(fiveCount >= 3) { - twentyCount += 1 fiveCount -= 3 } else { return false From 216088fe7c0d5192f4128084de9548848283a818 Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Mon, 7 Jun 2021 23:17:38 +0800 Subject: [PATCH 013/122] =?UTF-8?q?Update=20=E8=83=8C=E5=8C=85=E9=97=AE?= =?UTF-8?q?=E9=A2=98=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=80=E5=AE=8C=E5=85=A8?= =?UTF-8?q?=E8=83=8C=E5=8C=85.md=20=E6=B7=BB=E5=8A=A0=20python3=20?= =?UTF-8?q?=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0518.零钱兑换II.md | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/problems/0518.零钱兑换II.md b/problems/0518.零钱兑换II.md index 2dee030c..08aff9ac 100644 --- a/problems/0518.零钱兑换II.md +++ b/problems/0518.零钱兑换II.md @@ -33,7 +33,7 @@ 示例 3: 输入: amount = 10, coins = [10] 输出: 1 -  + 注意，你可以假设： * 0 <= amount (总金额) <= 5000 @@ -207,6 +207,21 @@ class Solution { Python： +```python3 +class Solution: + def change(self, amount: int, coins: List[int]) -> int: + dp = [0]*(amount + 1) + dp[0] = 1 + # 遍历物品 + for i in range(len(coins)): + # 遍历背包 + for j in range(coins[i], amount + 1): + dp[j] += dp[j - coins[i]] + return dp[amount] +``` + + + Go： From 484d320502e0756c61396c3beb461fcedd65229a Mon Sep 17 00:00:00 2001 From: LiangDazhu <42199191+LiangDazhu@users.noreply.github.com> Date: Tue, 8 Jun 2021 00:08:38 +0800 Subject: [PATCH 014/122] =?UTF-8?q?Update=200518.=E9=9B=B6=E9=92=B1?= =?UTF-8?q?=E5=85=91=E6=8D=A2II.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Added python version code --- problems/0518.零钱兑换II.md | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/problems/0518.零钱兑换II.md b/problems/0518.零钱兑换II.md index 2dee030c..7ee8818e 100644 --- a/problems/0518.零钱兑换II.md +++ b/problems/0518.零钱兑换II.md @@ -101,7 +101,7 @@ dp[j] （考虑coins[i]的组合总和） 就是所有的dp[j - coins[i]]（不 而本题要求凑成总和的组合数，元素之间要求没有顺序。 -所以纯完全背包是能凑成总结就行，不用管怎么凑的。 +所以纯完全背包是能凑成总和就行，不用管怎么凑的。 本题是求凑出来的方案个数，且每个方案个数是为组合数。 @@ -206,7 +206,16 @@ class Solution { ``` Python： - +```python +class Solution: + def change(self, amount: int, coins: List[int]) -> int: + dp = [0] * (amount + 1) + dp[0] = 1 + for i in range(len(coins)): + for j in range(coins[i], amount + 1): + dp[j] += dp[j - coins[i]] + return dp[amount] +``` Go： From 3fd92a4905c67df6fdf4c2238bd8c4f5f03fb595 Mon Sep 17 00:00:00 2001 From: jojoo15 <75017412+jojoo15@users.noreply.github.com> Date: Mon, 7 Jun 2021 20:55:40 +0200 Subject: [PATCH 015/122] =?UTF-8?q?=E4=BC=98=E5=8C=96=200455.=20=E5=88=86?= =?UTF-8?q?=E5=8F=91=E9=A5=BC=E5=B9=B2=20python3=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 优化 0455. 分发饼干 python3版本 --- problems/0455.分发饼干.md | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/problems/0455.分发饼干.md b/problems/0455.分发饼干.md index ecf7f132..4814d414 100644 --- a/problems/0455.分发饼干.md +++ b/problems/0455.分发饼干.md @@ -134,22 +134,17 @@ class Solution { ``` Python： -```python +```python3 class Solution: def findContentChildren(self, g: List[int], s: List[int]) -> int: - #先考虑胃口小的孩子 g.sort() s.sort() - i=j=0 - count = 0 - while(i= g[res]: #小饼干先喂饱小胃口 + res += 1 + return res ``` - Go： Javascript: From 881ddb1a551a7c9fe22b75adf159b0f8d768bb61 Mon Sep 17 00:00:00 2001 From: jojoo15 <75017412+jojoo15@users.noreply.github.com> Date: Mon, 7 Jun 2021 23:09:51 +0200 Subject: [PATCH 016/122] =?UTF-8?q?=E4=BC=98=E5=8C=96=200376.=20=E6=91=86?= =?UTF-8?q?=E5=8A=A8=E5=BA=8F=E5=88=97=20python3=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 优化 0376. 摆动序列 python3版本 --- problems/0376.摆动序列.md | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/problems/0376.摆动序列.md b/problems/0376.摆动序列.md index bbca5ea0..4d283eb0 100644 --- a/problems/0376.摆动序列.md +++ b/problems/0376.摆动序列.md @@ -138,20 +138,16 @@ class Solution { ``` Python： -```python +```python3 class Solution: def wiggleMaxLength(self, nums: List[int]) -> int: - #贪心 求波峰数量 + 波谷数量 - if len(nums)<=1: - return len(nums) - cur, pre = 0,0 #当前一对差值，前一对差值 - count = 1#默认最右边有一个峰值 - for i in range(len(nums)-1): - cur = nums[i+1] - nums[i] - if((cur>0 and pre<=0) or (cur<0 and pre>=0)): - count += 1 - pre = cur - return count + preC,curC,res = 0,0,1 #题目里nums长度大于等于1，当长度为1时，其实到不了for循环里去，所以不用考虑nums长度 + for i in range(len(nums) - 1): + curC = nums[i + 1] - nums[i] + if curC * preC <= 0 and curC !=0: #差值为0时，不算摆动 + res += 1 + preC = curC #如果当前差值和上一个差值为一正一负时，才需要用当前差值替代上一个差值 + return res ``` Go： From 895db79105f33131c5cf90f4db5e121457dbcb16 Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Tue, 8 Jun 2021 09:48:37 +0800 Subject: [PATCH 017/122] =?UTF-8?q?update=20=E4=BA=8C=E5=88=86=E6=9F=A5?= =?UTF-8?q?=E6=89=BE=EF=BC=9A=E6=B7=BB=E5=8A=A0=E4=BA=86python=E5=B7=A6?= =?UTF-8?q?=E9=97=AD=E5=8F=B3=E5=BC=80=E5=8C=BA=E9=97=B4=E7=9A=84=E4=BB=A3?= =?UTF-8?q?=E7=A0=81=EF=BC=8C=E5=90=8C=E6=97=B6=E5=AF=B9=E9=97=AE=E9=A2=98?= =?UTF-8?q?=E5=81=9A=E4=BA=86=E4=B8=8B=E6=8E=92=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0704.二分查找.md | 37 +++++++++++++++++++++++++++++------ 1 file changed, 31 insertions(+), 6 deletions(-) diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md index 0442ceaa..931e6e5c 100644 --- a/problems/0704.二分查找.md +++ b/problems/0704.二分查找.md @@ -13,16 +13,21 @@ 给定一个 n 个元素有序的（升序）整型数组 nums 和一个目标值 target  ，写一个函数搜索 nums 中的 target，如果目标值存在返回下标，否则返回 -1。 - 示例 1: + +``` 输入: nums = [-1,0,3,5,9,12], target = 9 输出: 4 解释: 9 出现在 nums 中并且下标为 4 +``` 示例 2: + +``` 输入: nums = [-1,0,3,5,9,12], target = 2 输出: -1 解释: 2 不存在 nums 中因此返回 -1 +``` 提示： @@ -146,7 +151,7 @@ public: ## 其他语言版本 -Java： +**Java：** （版本一）左闭右闭区间 @@ -192,9 +197,11 @@ class Solution { } ``` -Python： +**Python：** -```python3 +（版本一）左闭右闭区间 + +```python class Solution: def search(self, nums: List[int], target: int) -> int: left, right = 0, len(nums) - 1 @@ -211,8 +218,26 @@ class Solution: return -1 ``` +（版本二）左闭右开区间 -Go： +```python +class Solution: + def search(self, nums: List[int], target: int) -> int: + left,right =0, len(nums) + while left < right: + mid = (left + right) // 2 + if nums[mid] < target: + left = mid+1 + elif nums[mid] > target: + right = mid + else: + return mid + return -1 +``` + + + +**Go：** （版本一）左闭右闭区间 @@ -254,7 +279,7 @@ func search(nums []int, target int) int { } ``` -javaScript +**javaScript:** ```js From 7aad63754097b29ce05a36d8a8c1cfa7b711fb40 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E8=97=A4=E9=9C=B2?= <080301087@163.com> Date: Tue, 8 Jun 2021 10:06:37 +0800 Subject: [PATCH 018/122] =?UTF-8?q?Update=200102.=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=E7=9A=84=E5=B1=82=E5=BA=8F=E9=81=8D=E5=8E=86.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0102.二叉树的层序遍历.md | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md index c7fdf776..ca24cc8f 100644 --- a/problems/0102.二叉树的层序遍历.md +++ b/problems/0102.二叉树的层序遍历.md @@ -98,15 +98,13 @@ class Solution: out_list = [] while quene: + length = len(queue) # 这里一定要先求出队列的长度，不能用range(len(queue))，因为queue长度是变化的 in_list = [] - for _ in range(len(quene)): - node = quene.pop(0) - in_list.append(node.val) - if node.left: - quene.append(node.left) - if node.right: - quene.append(node.right) - + for _ in range(length): + curnode = queue.pop(0) #（默认移除列表最后一个元素）这里需要移除队列最头上的那个 + in_list.append(curnode.val) + if curnode.left : queue.append(curnode.left) + if curnode.right: queue.append(curnode.right) out_list.append(in_list) return out_list From d0822ea7eddd5f070dac5a6567c5bcc7e9d858cb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E8=97=A4=E9=9C=B2?= <080301087@163.com> Date: Tue, 8 Jun 2021 10:24:24 +0800 Subject: [PATCH 019/122] =?UTF-8?q?Update=200102.=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=E7=9A=84=E5=B1=82=E5=BA=8F=E9=81=8D=E5=8E=86.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0102.二叉树的层序遍历.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md index ca24cc8f..89d0dda7 100644 --- a/problems/0102.二叉树的层序遍历.md +++ b/problems/0102.二叉树的层序遍历.md @@ -98,12 +98,12 @@ class Solution: out_list = [] while quene: - length = len(queue) # 这里一定要先求出队列的长度，不能用range(len(queue))，因为queue长度是变化的 + length = len(queue) # 这里一定要先求出队列的长度，不能用range(len(queue))，因为queue长度是变化的 in_list = [] for _ in range(length): - curnode = queue.pop(0) #（默认移除列表最后一个元素）这里需要移除队列最头上的那个 + curnode = queue.pop(0) # （默认移除列表最后一个元素）这里需要移除队列最头上的那个 in_list.append(curnode.val) - if curnode.left : queue.append(curnode.left) + if curnode.left: queue.append(curnode.left) if curnode.right: queue.append(curnode.right) out_list.append(in_list) From fdb48d991f346b673462fb5b6546c855d0376614 Mon Sep 17 00:00:00 2001 From: lichuanming <1465802096@qq.com> Date: Tue, 8 Jun 2021 10:27:14 +0800 Subject: [PATCH 020/122] =?UTF-8?q?0053=20dp=20java=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0053.最大子序和（动态规划）.md | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/problems/0053.最大子序和（动态规划）.md b/problems/0053.最大子序和（动态规划）.md index 3cd687a6..e15f692e 100644 --- a/problems/0053.最大子序和（动态规划）.md +++ b/problems/0053.最大子序和（动态规划）.md @@ -95,7 +95,32 @@ public: Java： +```java + /** + * 1.dp[i]代表当前下标对应的最大值 + * 2.递推公式 dp[i] = max (dp[i-1]+nums[i],nums[i]) res = max(res,dp[i]) + * 3.初始化 都为 0 + * 4.遍历方向，从前往后 + * 5.举例推导结果。。。 + * + * @param nums + * @return + */ + public static int maxSubArray(int[] nums) { + if (nums.length == 0) { + return 0; + } + int res = nums[0]; + int[] dp = new int[nums.length]; + dp[0] = nums[0]; + for (int i = 1; i < nums.length; i++) { + dp[i] = Math.max(dp[i - 1] + nums[i], nums[i]); + res = res > dp[i] ? res : dp[i]; + } + return res; + } +``` Python： From b4e4779b9314787df1e3cd39933e531204355521 Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 10:48:33 +0800 Subject: [PATCH 021/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E9=97=AE=E9=A2=98=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=80=E5=AE=8C?= =?UTF-8?q?=E5=85=A8=E8=83=8C=E5=8C=85=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../背包问题理论基础完全背包.md | 51 +++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/problems/背包问题理论基础完全背包.md b/problems/背包问题理论基础完全背包.md index 9997dff3..a5a708cf 100644 --- a/problems/背包问题理论基础完全背包.md +++ b/problems/背包问题理论基础完全背包.md @@ -220,7 +220,58 @@ if __name__ == '__main__': Go： +```go +// test_CompletePack1 先遍历物品, 在遍历背包 +func test_CompletePack1(weight, value []int, bagWeight int) int { + // 定义dp数组 和初始化 + dp := make([]int, bagWeight+1) + // 遍历顺序 + for i := 0; i < len(weight); i++ { + // 正序会多次添加 value[i] + for j := weight[i]; j <= bagWeight; j++ { + // 推导公式 + dp[j] = max(dp[j], dp[j-weight[i]]+value[i]) + // debug + //fmt.Println(dp) + } + } + return dp[bagWeight] +} + +// test_CompletePack2 先遍历背包, 在遍历物品 +func test_CompletePack2(weight, value []int, bagWeight int) int { + // 定义dp数组 和初始化 + dp := make([]int, bagWeight+1) + // 遍历顺序 + // j从0 开始 + for j := 0; j <= bagWeight; j++ { + for i := 0; i < len(weight); i++ { + if j >= weight[i] { + // 推导公式 + dp[j] = max(dp[j], dp[j-weight[i]]+value[i]) + } + // debug + //fmt.Println(dp) + } + } + return dp[bagWeight] +} + +func max(a, b int) int { + if a > b { + return a + } + return b +} + +func main() { + weight := []int{1, 3, 4} + price := []int{15, 20, 30} + fmt.Println(test_CompletePack1(weight, price, 4)) + fmt.Println(test_CompletePack2(weight, price, 4)) +} +``` From 16f5dd51da50d2081a220ce264269cd678c2b8d4 Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 10:56:50 +0800 Subject: [PATCH 022/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00518.=E9=9B=B6?= =?UTF-8?q?=E9=92=B1=E5=85=91=E6=8D=A2II?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0518.零钱兑换II.md | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/problems/0518.零钱兑换II.md b/problems/0518.零钱兑换II.md index 2dee030c..4ab4a6df 100644 --- a/problems/0518.零钱兑换II.md +++ b/problems/0518.零钱兑换II.md @@ -209,7 +209,24 @@ Python： Go： - +```go +func change(amount int, coins []int) int { + // 定义dp数组 + dp := make([]int, amount+1) + // 初始化,0大小的背包, 当然是不装任何东西了, 就是1种方法 + dp[0] = 1 + // 遍历顺序 + // 遍历物品 + for i := 0 ;i < len(coins);i++ { + // 遍历背包 + for j:= coins[i] ; j <= amount ;j++ { + // 推导公式 + dp[j] += dp[j-coins[i]] + } + } + return dp[amount] +} +``` From 2dbe7175cb332876e46e0309c333ca1c1bdf962f Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:36:10 -0700 Subject: [PATCH 023/122] =?UTF-8?q?Update=200121.=E4=B9=B0=E5=8D=96?= =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?= =?UTF-8?q?.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0121.买卖股票的最佳时机.md | 41 ++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/problems/0121.买卖股票的最佳时机.md b/problems/0121.买卖股票的最佳时机.md index d018efb7..259fff34 100644 --- a/problems/0121.买卖股票的最佳时机.md +++ b/problems/0121.买卖股票的最佳时机.md @@ -244,6 +244,47 @@ class Solution { // 动态规划解法 Python： +> 贪心法： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + low = float("inf") + result = 0 + for i in range(len(prices)): + low = min(low, prices[i]) #取最左最小价格 + result = max(result, prices[i] - low) #直接取最大区间利润 + return result +``` + +> 动态规划：版本一 +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + length = len(prices) + if len == 0: + return 0 + dp = [[0] * 2 for _ in range(length)] + dp[0][0] = -prices[0] + dp[0][1] = 0 + for i in range(1, length): + dp[i][0] = max(dp[i-1][0], -prices[i]) + dp[i][1] = max(dp[i-1][1], prices[i] + dp[i-1][0]) + return dp[-1][1] +``` + +> 动态规划：版本二 +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + length = len(prices) + dp = [[0] * 2 for _ in range(2)] #注意这里只开辟了一个2 * 2大小的二维数组 + dp[0][0] = -prices[0] + dp[0][1] = 0 + for i in range(1, length): + dp[i % 2][0] = max(dp[(i-1) % 2][0], -prices[i]) + dp[i % 2][1] = max(dp[(i-1) % 2][1], prices[i] + dp[(i-1) % 2][0]) + return dp[(length-1) % 2][1] +``` Go： ```Go From 4973e988d719a67020cd38de5d6d5e23e1d336d5 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:41:42 -0700 Subject: [PATCH 024/122] =?UTF-8?q?Update=200122.=E4=B9=B0=E5=8D=96?= =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?= =?UTF-8?q?II=EF=BC=88=E5=8A=A8=E6=80=81=E8=A7=84=E5=88=92=EF=BC=89.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...票的最佳时机II（动态规划）.md | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/problems/0122.买卖股票的最佳时机II（动态规划）.md b/problems/0122.买卖股票的最佳时机II（动态规划）.md index ba277fdc..1215025e 100644 --- a/problems/0122.买卖股票的最佳时机II（动态规划）.md +++ b/problems/0122.买卖股票的最佳时机II（动态规划）.md @@ -171,6 +171,33 @@ class Solution Python： +> 版本一： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + length = len(prices) + dp = [[0] * 2 for _ in range(length)] + dp[0][0] = -prices[0] + dp[0][1] = 0 + for i in range(1, length): + dp[i][0] = max(dp[i-1][0], dp[i-1][1] - prices[i]) #注意这里是和121. 买卖股票的最佳时机唯一不同的地方 + dp[i][1] = max(dp[i-1][1], dp[i-1][0] + prices[i]) + return dp[-1][1] +``` + +> 版本二： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + length = len(prices) + dp = [[0] * 2 for _ in range(2)] #注意这里只开辟了一个2 * 2大小的二维数组 + dp[0][0] = -prices[0] + dp[0][1] = 0 + for i in range(1, length): + dp[i % 2][0] = max(dp[(i-1) % 2][0], dp[(i-1) % 2][1] - prices[i]) + dp[i % 2][1] = max(dp[(i-1) % 2][1], dp[(i-1) % 2][0] + prices[i]) + return dp[(length-1) % 2][1] +``` Go： From 84e90f2344791fca696ca34165ddd1a449d643ca Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:43:59 -0700 Subject: [PATCH 025/122] =?UTF-8?q?Update=200123.=E4=B9=B0=E5=8D=96?= =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?= =?UTF-8?q?III.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0123.买卖股票的最佳时机III.md | 34 +++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/problems/0123.买卖股票的最佳时机III.md b/problems/0123.买卖股票的最佳时机III.md index 24370d38..fccb187d 100644 --- a/problems/0123.买卖股票的最佳时机III.md +++ b/problems/0123.买卖股票的最佳时机III.md @@ -229,6 +229,40 @@ class Solution { // 动态规划 Python： +> 版本一： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + if len(prices) == 0: + return 0 + dp = [[0] * 5 for _ in range(len(prices))] + dp[0][1] = -prices[0] + dp[0][3] = -prices[0] + for i in range(1, len(prices)): + dp[i][0] = dp[i-1][0] + dp[i][1] = max(dp[i-1][1], dp[i-1][0] - prices[i]) + dp[i][2] = max(dp[i-1][2], dp[i-1][1] + prices[i]) + dp[i][3] = max(dp[i-1][3], dp[i-1][2] - prices[i]) + dp[i][4] = max(dp[i-1][4], dp[i-1][3] + prices[i]) + return dp[-1][4] +``` + +> 版本二： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + if len(prices) == 0: + return 0 + dp = [0] * 5 + dp[1] = -prices[0] + dp[3] = -prices[0] + for i in range(1, len(prices)): + dp[1] = max(dp[1], dp[0] - prices[i]) + dp[2] = max(dp[2], dp[1] + prices[i]) + dp[3] = max(dp[3], dp[2] - prices[i]) + dp[4] = max(dp[4], dp[3] + prices[i]) + return dp[4] +``` Go： From 6ee7831f5739edc8915d04c4842736920fc773dd Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:45:24 -0700 Subject: [PATCH 026/122] =?UTF-8?q?Update=200188.=E4=B9=B0=E5=8D=96?= =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?= =?UTF-8?q?IV.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0188.买卖股票的最佳时机IV.md | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/problems/0188.买卖股票的最佳时机IV.md b/problems/0188.买卖股票的最佳时机IV.md index f0adc237..431c292b 100644 --- a/problems/0188.买卖股票的最佳时机IV.md +++ b/problems/0188.买卖股票的最佳时机IV.md @@ -212,6 +212,20 @@ class Solution { //动态规划 Python： +```python +class Solution: + def maxProfit(self, k: int, prices: List[int]) -> int: + if len(prices) == 0: + return 0 + dp = [[0] * (2*k+1) for _ in range(len(prices))] + for j in range(1, 2*k, 2): + dp[0][j] = -prices[0] + for i in range(1, len(prices)): + for j in range(0, 2*k-1, 2): + dp[i][j+1] = max(dp[i-1][j+1], dp[i-1][j] - prices[i]) + dp[i][j+2] = max(dp[i-1][j+2], dp[i-1][j+1] + prices[i]) + return dp[-1][2*k] +``` Go： From eeefc8499b70137fdc6ddd07ab6940959fd3124e Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:52:32 -0700 Subject: [PATCH 027/122] =?UTF-8?q?Update=200309.=E6=9C=80=E4=BD=B3?= =?UTF-8?q?=E4=B9=B0=E5=8D=96=E8=82=A1=E7=A5=A8=E6=97=B6=E6=9C=BA=E5=90=AB?= =?UTF-8?q?=E5=86=B7=E5=86=BB=E6=9C=9F.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0309.最佳买卖股票时机含冷冻期.md | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/problems/0309.最佳买卖股票时机含冷冻期.md b/problems/0309.最佳买卖股票时机含冷冻期.md index 44ca2b26..4667c122 100644 --- a/problems/0309.最佳买卖股票时机含冷冻期.md +++ b/problems/0309.最佳买卖股票时机含冷冻期.md @@ -189,6 +189,21 @@ class Solution { Python： +```python +class Solution: + def maxProfit(self, prices: List[int]) -> int: + n = len(prices) + if n == 0: + return 0 + dp = [[0] * 4 for _ in range(n)] + dp[0][0] = -prices[0] #持股票 + for i in range(1, n): + dp[i][0] = max(dp[i-1][0], max(dp[i-1][3], dp[i-1][1]) - prices[i]) + dp[i][1] = max(dp[i-1][1], dp[i-1][3]) + dp[i][2] = dp[i-1][0] + prices[i] + dp[i][3] = dp[i-1][2] + return max(dp[n-1][3], dp[n-1][1], dp[n-1][2]) +``` Go： From 7036c5d1b27ea616872393ccde6f4f92882345cd Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 21:56:50 -0700 Subject: [PATCH 028/122] =?UTF-8?q?Update=200714.=E4=B9=B0=E5=8D=96?= =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?= =?UTF-8?q?=E5=90=AB=E6=89=8B=E7=BB=AD=E8=B4=B9=EF=BC=88=E5=8A=A8=E6=80=81?= =?UTF-8?q?=E8=A7=84=E5=88=92=EF=BC=89.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...的最佳时机含手续费（动态规划）.md | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/problems/0714.买卖股票的最佳时机含手续费（动态规划）.md b/problems/0714.买卖股票的最佳时机含手续费（动态规划）.md index 14b5859b..5eb3453b 100644 --- a/problems/0714.买卖股票的最佳时机含手续费（动态规划）.md +++ b/problems/0714.买卖股票的最佳时机含手续费（动态规划）.md @@ -139,7 +139,17 @@ public int maxProfit(int[] prices, int fee) { ``` Python： - +```python +class Solution: + def maxProfit(self, prices: List[int], fee: int) -> int: + n = len(prices) + dp = [[0] * 2 for _ in range(n)] + dp[0][0] = -prices[0] #持股票 + for i in range(1, n): + dp[i][0] = max(dp[i-1][0], dp[i-1][1] - prices[i]) + dp[i][1] = max(dp[i-1][1], dp[i-1][0] + prices[i] - fee) + return max(dp[-1][0], dp[-1][1]) +``` Go： From 667a2a6e6fe2a5d122c262b54417546226b42ea2 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 22:14:23 -0700 Subject: [PATCH 029/122] =?UTF-8?q?Update=200300.=E6=9C=80=E9=95=BF?= =?UTF-8?q?=E4=B8=8A=E5=8D=87=E5=AD=90=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0300.最长上升子序列.md | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/problems/0300.最长上升子序列.md b/problems/0300.最长上升子序列.md index 02105a7c..8b4ad5b1 100644 --- a/problems/0300.最长上升子序列.md +++ b/problems/0300.最长上升子序列.md @@ -130,7 +130,20 @@ class Solution { ``` Python： - +```python +class Solution: + def lengthOfLIS(self, nums: List[int]) -> int: + if len(nums) <= 1: + return len(nums) + dp = [1] * len(nums) + result = 0 + for i in range(1, len(nums)): + for j in range(0, i): + if nums[i] > nums[j]: + dp[i] = max(dp[i], dp[j] + 1) + result = max(result, dp[i]) #取长的子序列 + return result +``` Go： ```go From 199390e9ac4619bc51817e0cb703a86affe93a0d Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 22:29:09 -0700 Subject: [PATCH 030/122] =?UTF-8?q?Update=200674.=E6=9C=80=E9=95=BF?= =?UTF-8?q?=E8=BF=9E=E7=BB=AD=E9=80=92=E5=A2=9E=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0674.最长连续递增序列.md | 31 +++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/problems/0674.最长连续递增序列.md b/problems/0674.最长连续递增序列.md index 636ee0cc..31ab6b0e 100644 --- a/problems/0674.最长连续递增序列.md +++ b/problems/0674.最长连续递增序列.md @@ -184,6 +184,37 @@ Java： Python： +> 动态规划： +```python +class Solution: + def findLengthOfLCIS(self, nums: List[int]) -> int: + if len(nums) == 0: + return 0 + result = 1 + dp = [1] * len(nums) + for i in range(len(nums)-1): + if nums[i+1] > nums[i]: #连续记录 + dp[i+1] = dp[i] + 1 + result = max(result, dp[i+1]) + return result +``` + +> 贪心法： +```python +class Solution: + def findLengthOfLCIS(self, nums: List[int]) -> int: + if len(nums) == 0: + return 0 + result = 1 #连续子序列最少也是1 + count = 1 + for i in range(len(nums)-1): + if nums[i+1] > nums[i]: #连续记录 + count += 1 + else: #不连续，count从头开始 + count = 1 + result = max(result, count) + return result +``` Go： From fe1c2aadfabf462c910e4989aa0c7c96f0560243 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 22:47:00 -0700 Subject: [PATCH 031/122] =?UTF-8?q?Update=200718.=E6=9C=80=E9=95=BF?= =?UTF-8?q?=E9=87=8D=E5=A4=8D=E5=AD=90=E6=95=B0=E7=BB=84.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0718.最长重复子数组.md | 30 ++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/problems/0718.最长重复子数组.md b/problems/0718.最长重复子数组.md index be9109b2..204a513b 100644 --- a/problems/0718.最长重复子数组.md +++ b/problems/0718.最长重复子数组.md @@ -158,6 +158,36 @@ Java： Python： +> 动态规划： +```python +class Solution: + def findLength(self, A: List[int], B: List[int]) -> int: + dp = [[0] * (len(B)+1) for _ in range(len(A)+1)] + result = 0 + for i in range(1, len(A)+1): + for j in range(1, len(B)+1): + if A[i-1] == B[j-1]: + dp[i][j] = dp[i-1][j-1] + 1 + result = max(result, dp[i][j]) + return result +``` + +> 动态规划：滚动数组 +```python +class Solution: + def findLength(self, A: List[int], B: List[int]) -> int: + dp = [0] * (len(B) + 1) + result = 0 + for i in range(1, len(A)+1): + for j in range(len(B), 0, -1): + if A[i-1] == B[j-1]: + dp[j] = dp[j-1] + 1 + else: + dp[j] = 0 #注意这里不相等的时候要有赋0的操作 + result = max(result, dp[j]) + return result +``` + Go： ```Go From d16cd90a6a682f68508246409deaf97d7e4b7590 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Mon, 7 Jun 2021 22:51:06 -0700 Subject: [PATCH 032/122] =?UTF-8?q?Update=201035.=E4=B8=8D=E7=9B=B8?= =?UTF-8?q?=E4=BA=A4=E7=9A=84=E7=BA=BF.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/1035.不相交的线.md | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/problems/1035.不相交的线.md b/problems/1035.不相交的线.md index 039030d2..be159543 100644 --- a/problems/1035.不相交的线.md +++ b/problems/1035.不相交的线.md @@ -93,7 +93,18 @@ Java： ``` Python： - +```python +class Solution: + def maxUncrossedLines(self, A: List[int], B: List[int]) -> int: + dp = [[0] * (len(B)+1) for _ in range(len(A)+1)] + for i in range(1, len(A)+1): + for j in range(1, len(B)+1): + if A[i-1] == B[j-1]: + dp[i][j] = dp[i-1][j-1] + 1 + else: + dp[i][j] = max(dp[i-1][j], dp[i][j-1]) + return dp[-1][-1] +``` Go： From 5eb21ea5676dd566caa4b2896a4cf73af399879c Mon Sep 17 00:00:00 2001 From: youngyangyang04 <826123027@qq.com> Date: Tue, 8 Jun 2021 15:09:07 +0800 Subject: [PATCH 033/122] Update --- README.md | 5 ++++ problems/0104.二叉树的最大深度.md | 34 ----------------------- problems/0383.赎金信.md | 10 +++---- problems/面试题02.07.链表相交.md | 4 +-- 4 files changed, 12 insertions(+), 41 deletions(-) diff --git a/README.md b/README.md index 58f71049..4fa9100d 100644 --- a/README.md +++ b/README.md @@ -17,6 +17,11 @@

+

+ + + + # LeetCode 刷题攻略 diff --git a/problems/0104.二叉树的最大深度.md b/problems/0104.二叉树的最大深度.md index 5f0fe411..f1a84978 100644 --- a/problems/0104.二叉树的最大深度.md +++ b/problems/0104.二叉树的最大深度.md @@ -193,40 +193,6 @@ public: }; ``` -使用栈来模拟后序遍历依然可以 - -```C++ -class Solution { -public: - int maxDepth(TreeNode* root) { - stack st; - if (root != NULL) st.push(root); - int depth = 0; - int result = 0; - while (!st.empty()) { - TreeNode* node = st.top(); - if (node != NULL) { - st.pop(); - st.push(node); // 中 - st.push(NULL); - depth++; - if (node->right) st.push(node->right); // 右 - if (node->left) st.push(node->left); // 左 - - } else { - st.pop(); - node = st.top(); - st.pop(); - depth--; - } - result = result > depth ? result : depth; - } - return result; - - } -}; -``` - ## 其他语言版本 diff --git a/problems/0383.赎金信.md b/problems/0383.赎金信.md index 23e2c5fd..2f3c4f4d 100644 --- a/problems/0383.赎金信.md +++ b/problems/0383.赎金信.md @@ -22,13 +22,13 @@ https://leetcode-cn.com/problems/ransom-note/ 你可以假设两个字符串均只含有小写字母。 -canConstruct("a", "b") -> false -canConstruct("aa", "ab") -> false -canConstruct("aa", "aab") -> true +canConstruct("a", "b") -> false +canConstruct("aa", "ab") -> false +canConstruct("aa", "aab") -> true ## 思路 -这道题目和[242.有效的字母异位词](https://mp.weixin.qq.com/s/vM6OszkM6L1Mx2Ralm9Dig)很像，[242.有效的字母异位词](https://mp.weixin.qq.com/s/vM6OszkM6L1Mx2Ralm9Dig)相当于求 字符串a 和 字符串b 是否可以相互组成 ，而这道题目是求 字符串a能否组成字符串b，而不用管字符串b 能不能组成字符串a。 +这道题目和[242.有效的字母异位词](https://mp.weixin.qq.com/s/ffS8jaVFNUWyfn_8T31IdA)很像，[242.有效的字母异位词](https://mp.weixin.qq.com/s/ffS8jaVFNUWyfn_8T31IdA)相当于求 字符串a 和 字符串b 是否可以相互组成 ，而这道题目是求 字符串a能否组成字符串b，而不用管字符串b 能不能组成字符串a。 本题判断第一个字符串ransom能不能由第二个字符串magazines里面的字符构成，但是这里需要注意两点。 @@ -75,7 +75,7 @@ public: 依然是数组在哈希法中的应用。 -一些同学可能想，用数组干啥，都用map完事了，**其实在本题的情况下，使用map的空间消耗要比数组大一些的，因为map要维护红黑树或者哈希表，而且还要做哈希函数。 所以数组更加简单直接有效！** +一些同学可能想，用数组干啥，都用map完事了，**其实在本题的情况下，使用map的空间消耗要比数组大一些的，因为map要维护红黑树或者哈希表，而且还要做哈希函数，是费时的！数据量大的话就能体现出来差别了。 所以数组更加简单直接有效！** 代码如下： diff --git a/problems/面试题02.07.链表相交.md b/problems/面试题02.07.链表相交.md index 78f34e71..c6779427 100644 --- a/problems/面试题02.07.链表相交.md +++ b/problems/面试题02.07.链表相交.md @@ -32,11 +32,11 @@ 看如下两个链表，目前curA指向链表A的头结点，curB指向链表B的头结点： -![面试题02.07.链表相交_1](https://code-thinking.cdn.bcebos.com/pics/%E9%9D%A2%E8%AF%95%E9%A2%9802.07.%E9%93%BE%E8%A1%A8%E7%9B%B8%E4%BA%A4_1.png)v +![面试题02.07.链表相交_1](https://code-thinking.cdn.bcebos.com/pics/面试题02.07.链表相交_1.png) 我们求出两个链表的长度，并求出两个链表长度的差值，然后让curA移动到，和curB 末尾对齐的位置，如图： -![面试题02.07.链表相交_2](https://code-thinking.cdn.bcebos.com/pics/%E9%9D%A2%E8%AF%95%E9%A2%9802.07.%E9%93%BE%E8%A1%A8%E7%9B%B8%E4%BA%A4_2.png) +![面试题02.07.链表相交_2](https://code-thinking.cdn.bcebos.com/pics/面试题02.07.链表相交_2.png) 此时我们就可以比较curA和curB是否相同，如果不相同，同时向后移动curA和curB，如果遇到curA == curB，则找到焦点。 From 5243b5eac0ca69b59d6dac1a5e8dd50bd7a94fd9 Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 15:24:35 +0800 Subject: [PATCH 034/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00377.=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8C=E2=85=A3=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0377.组合总和Ⅳ.md | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/problems/0377.组合总和Ⅳ.md b/problems/0377.组合总和Ⅳ.md index c6dc3d42..d0394706 100644 --- a/problems/0377.组合总和Ⅳ.md +++ b/problems/0377.组合总和Ⅳ.md @@ -183,7 +183,23 @@ class Solution: Go： - +```go +func combinationSum4(nums []int, target int) int { + //定义dp数组 + dp := make([]int, target+1) + // 初始化 + dp[0] = 1 + // 遍历顺序, 先遍历背包,再循环遍历物品 + for j:=0;j<=target;j++ { + for i:=0 ;i < len(nums);i++ { + if j >= nums[i] { + dp[j] += dp[j-nums[i]] + } + } + } + return dp[target] +} +``` From 13fe71327758c072a7b817e98e0ebfbcd6adba99 Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 15:41:05 +0800 Subject: [PATCH 035/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00070.=E7=88=AC?= =?UTF-8?q?=E6=A5=BC=E6=A2=AF=E5=AE=8C=E5=85=A8=E8=83=8C=E5=8C=85=E7=89=88?= =?UTF-8?q?=E6=9C=AC=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0070.爬楼梯完全背包版本.md | 21 +++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/problems/0070.爬楼梯完全背包版本.md b/problems/0070.爬楼梯完全背包版本.md index 69750f8f..9fc33bb8 100644 --- a/problems/0070.爬楼梯完全背包版本.md +++ b/problems/0070.爬楼梯完全背包版本.md @@ -149,7 +149,26 @@ Python： Go： - +```go +func climbStairs(n int) int { + //定义 + dp := make([]int, n+1) + //初始化 + dp[0] = 1 + // 本题物品只有两个1,2 + m := 2 + // 遍历顺序 + for j := 1; j <= n; j++ { //先遍历背包 + for i := 1; i <= m; i++ { //再遍历物品 + if j >= i { + dp[j] += dp[j-i] + } + //fmt.Println(dp) + } + } + return dp[n] +} +``` From 12b62a4e1ced243fd66fcda289ded88f99fd032f Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 17:07:06 +0800 Subject: [PATCH 036/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00322.=E9=9B=B6?= =?UTF-8?q?=E9=92=B1=E5=85=91=E6=8D=A2=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0322.零钱兑换.md | 61 +++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/problems/0322.零钱兑换.md b/problems/0322.零钱兑换.md index ddcd739b..2c9ff8cf 100644 --- a/problems/0322.零钱兑换.md +++ b/problems/0322.零钱兑换.md @@ -211,7 +211,68 @@ Python： Go： +```go +// 版本一, 先遍历物品,再遍历背包 +func coinChange1(coins []int, amount int) int { + dp := make([]int, amount+1) + // 初始化dp[0] + dp[0] = 0 + // 初始化为math.MaxInt32 + for j := 1; j <= amount; j++ { + dp[j] = math.MaxInt32 + } + // 遍历物品 + for i := 0; i < len(coins); i++ { + // 遍历背包 + for j := coins[i]; j <= amount; j++ { + //if dp[j-coins[i]] != math.MaxInt32 { + // 推导公式 + dp[j] = min(dp[j], dp[j-coins[i]]+1) + fmt.Println(dp,j,i) + //} + } + } + // 没找到能装满背包的, 就返回-1 + if dp[amount] == math.MaxInt32 { + return -1 + } + return dp[amount] +} + +// 版本二,先遍历背包,再遍历物品 +func coinChange2(coins []int, amount int) int { + dp := make([]int, amount+1) + // 初始化dp[0] + dp[0] = 0 + // 遍历背包,从1开始 + for j := 1; j <= amount; j++ { + // 初始化为math.MaxInt32 + dp[j] = math.MaxInt32 + // 遍历物品 + for i := 0; i < len(coins); i++ { + if j >= coins[i] && dp[j-coins[i]] != math.MaxInt32 { + // 推导公式 + dp[j] = min(dp[j], dp[j-coins[i]]+1) + //fmt.Println(dp) + } + } + } + // 没找到能装满背包的, 就返回-1 + if dp[amount] == math.MaxInt32 { + return -1 + } + return dp[amount] +} + +func min(a, b int) int { + if a < b { + return a + } + return b +} + +``` From 41623a2725f6e419f2d4bdef3bfce3a2afbee9d8 Mon Sep 17 00:00:00 2001 From: zhangzw Date: Tue, 8 Jun 2021 17:33:44 +0800 Subject: [PATCH 037/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00279.=E5=AE=8C?= =?UTF-8?q?=E5=85=A8=E5=B9=B3=E6=96=B9=E6=95=B0=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0279.完全平方数.md | 48 ++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/problems/0279.完全平方数.md b/problems/0279.完全平方数.md index 8d8c1f48..8d8b161c 100644 --- a/problems/0279.完全平方数.md +++ b/problems/0279.完全平方数.md @@ -186,7 +186,55 @@ Python： Go： +```go +// 版本一,先遍历物品, 再遍历背包 +func numSquares1(n int) int { + //定义 + dp := make([]int, n+1) + // 初始化 + dp[0] = 0 + for i := 1; i <= n; i++ { + dp[i] = math.MaxInt32 + } + // 遍历物品 + for i := 1; i <= n; i++ { + // 遍历背包 + for j := i*i; j <= n; j++ { + dp[j] = min(dp[j], dp[j-i*i]+1) + } + } + return dp[n] +} + +// 版本二,先遍历背包, 再遍历物品 +func numSquares2(n int) int { + //定义 + dp := make([]int, n+1) + // 初始化 + dp[0] = 0 + // 遍历背包 + for j := 1; j <= n; j++ { + //初始化 + dp[j] = math.MaxInt32 + // 遍历物品 + for i := 1; i <= n; i++ { + if j >= i*i { + dp[j] = min(dp[j], dp[j-i*i]+1) + } + } + } + + return dp[n] +} + +func min(a, b int) int { + if a < b { + return a + } + return b +} +``` From 95694ede2d4b4ad9d6f6a0528aa3fb7542012d60 Mon Sep 17 00:00:00 2001 From: liulei <718356979@qq.com> Date: Tue, 8 Jun 2021 19:43:03 +0800 Subject: [PATCH 038/122] =?UTF-8?q?=E6=9B=B4=E6=96=B0=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E5=9F=BA=E7=A1=80=E7=90=86=E8=AE=BA01=E8=83=8C=E5=8C=85-1?= =?UTF-8?q?=EF=BC=8C=20=E5=A2=9E=E5=8A=A0Java=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-1.md | 39 +++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index de4508ad..852c489b 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -265,9 +265,46 @@ int main() { ## 其他语言版本 - Java： +```java + public static void main(String[] args) { + int[] weight = {1, 3, 4}; + int[] value = {15, 20, 30}; + int bagSize = 4; + testWeightBagProblem(weight, value, bagSize); + } + + public static void testWeightBagProblem(int[] weight, int[] value, int bagSize){ + int wLen = weight.length, value0 = 0; + //定义dp数组：dp[i][j]表示背包容量为j时，前i个物品能获得的最大价值 + int[][] dp = new int[wLen + 1][bagSize + 1]; + //初始化：背包容量为0时，能获得的价值都为0 + for (int i = 0; i <= wLen; i++){ + dp[i][0] = value0; + } + //遍历顺序：先遍历物品，再遍历背包容量 + for (int i = 1; i <= wLen; i++){ + for (int j = 1; j <= bagSize; j++){ + if (j < weight[i - 1]){ + dp[i][j] = dp[i - 1][j]; + }else{ + dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - weight[i - 1]] + value[i - 1]); + } + } + } + //打印dp数组 + for (int i = 0; i <= wLen; i++){ + for (int j = 0; j <= bagSize; j++){ + System.out.print(dp[i][j] + " "); + } + System.out.print("\n"); + } + } +``` + + + Python： From 001a7a8b2dfeb875065234960c6307ae0bb67cca Mon Sep 17 00:00:00 2001 From: ChrisLin Date: Tue, 8 Jun 2021 23:31:52 +0800 Subject: [PATCH 039/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00062.=E4=B8=8D?= =?UTF-8?q?=E5=90=8C=E8=B7=AF=E5=BE=84Javascript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0062.不同路径.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/problems/0062.不同路径.md b/problems/0062.不同路径.md index 60b65818..47cb41af 100644 --- a/problems/0062.不同路径.md +++ b/problems/0062.不同路径.md @@ -308,6 +308,27 @@ func uniquePaths(m int, n int) int { } ``` +Javascript： +```Javascript +var uniquePaths = function(m, n) { + const dp = Array(m).fill().map(item => Array(n)) + + for (let i = 0; i < m; ++i) { + dp[i][0] = 1 + } + + for (let i = 0; i < n; ++i) { + dp[0][i] = 1 + } + + for (let i = 1; i < m; ++i) { + for (let j = 1; j < n; ++j) { + dp[i][j] = dp[i - 1][j] + dp[i][j - 1] + } + } + return dp[m - 1][n - 1] +}; +``` ----------------------- From b323aec3fcf81211126e1be3e4112ac3ea4aca6f Mon Sep 17 00:00:00 2001 From: ChrisLin Date: Tue, 8 Jun 2021 23:39:17 +0800 Subject: [PATCH 040/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00063.=E4=B8=8D?= =?UTF-8?q?=E5=90=8C=E8=B7=AF=E5=BE=84II=20Javascript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0063.不同路径II.md | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/problems/0063.不同路径II.md b/problems/0063.不同路径II.md index eeecad70..52f00322 100644 --- a/problems/0063.不同路径II.md +++ b/problems/0063.不同路径II.md @@ -279,6 +279,30 @@ func uniquePathsWithObstacles(obstacleGrid [][]int) int { ``` +Javascript +``` Javascript +var uniquePathsWithObstacles = function(obstacleGrid) { + const m = obstacleGrid.length + const n = obstacleGrid[0].length + const dp = Array(m).fill().map(item => Array(n).fill(0)) + + for (let i = 0; i < m && obstacleGrid[i][0] === 0; ++i) { + dp[i][0] = 1 + } + + for (let i = 0; i < n && obstacleGrid[0][i] === 0; ++i) { + dp[0][i] = 1 + } + + for (let i = 1; i < m; ++i) { + for (let j = 1; j < n; ++j) { + dp[i][j] = obstacleGrid[i][j] === 1 ? 0 : dp[i - 1][j] + dp[i][j - 1] + } + } + + return dp[m - 1][n - 1] +}; +``` ----------------------- From 9c0f605e16bc743fa1d2b048d11a9a8cb273ecda Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 13:55:16 -0700 Subject: [PATCH 041/122] =?UTF-8?q?Update=200053.=E6=9C=80=E5=A4=A7?= =?UTF-8?q?=E5=AD=90=E5=BA=8F=E5=92=8C=EF=BC=88=E5=8A=A8=E6=80=81=E8=A7=84?= =?UTF-8?q?=E5=88=92=EF=BC=89.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0053.最大子序和（动态规划）.md | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/problems/0053.最大子序和（动态规划）.md b/problems/0053.最大子序和（动态规划）.md index 3cd687a6..2a17df20 100644 --- a/problems/0053.最大子序和（动态规划）.md +++ b/problems/0053.最大子序和（动态规划）.md @@ -98,7 +98,19 @@ Java： Python： - +```python +class Solution: + def maxSubArray(self, nums: List[int]) -> int: + if len(nums) == 0: + return 0 + dp = [0] * len(nums) + dp[0] = nums[0] + result = dp[0] + for i in range(1, len(nums)): + dp[i] = max(dp[i-1] + nums[i], nums[i]) #状态转移公式 + result = max(result, dp[i]) #result 保存dp[i]的最大值 + return result +``` Go： From 7beb711f0df90795c0f4df537b8aaab897d5e98c Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Wed, 9 Jun 2021 08:22:29 +0800 Subject: [PATCH 042/122] =?UTF-8?q?0406.=E6=A0=B9=E6=8D=AE=E8=BA=AB?= =?UTF-8?q?=E9=AB=98=E4=BD=93=E9=87=8D=E9=87=8D=E5=BB=BA=E9=98=9F=E5=88=97?= =?UTF-8?q?=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0406.根据身高重建队列.md | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/problems/0406.根据身高重建队列.md b/problems/0406.根据身高重建队列.md index eec9680b..9aca5b94 100644 --- a/problems/0406.根据身高重建队列.md +++ b/problems/0406.根据身高重建队列.md @@ -226,7 +226,25 @@ class Solution: Go： +Javascript: +```Javascript +var reconstructQueue = function(people) { + let queue = [] + people.sort((a, b ) => { + if(b[0] !== a[0]) { + return b[0] - a[0] + } else { + return a[1] - b[1] + } + + }) + for(let i = 0; i < people.length; i++) { + queue.splice(people[i][1], 0, people[i]) + } + return queue +}; +``` ----------------------- From 95fa60c32cca538aa20115320a093bdee0500409 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 17:53:45 -0700 Subject: [PATCH 043/122] =?UTF-8?q?Update=200115.=E4=B8=8D=E5=90=8C?= =?UTF-8?q?=E7=9A=84=E5=AD=90=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0115.不同的子序列.md | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/problems/0115.不同的子序列.md b/problems/0115.不同的子序列.md index 1661acf8..e54389aa 100644 --- a/problems/0115.不同的子序列.md +++ b/problems/0115.不同的子序列.md @@ -148,7 +148,22 @@ Java： Python： - +```python +class Solution: + def numDistinct(self, s: str, t: str) -> int: + dp = [[0] * (len(t)+1) for _ in range(len(s)+1)] + for i in range(len(s)): + dp[i][0] = 1 + for j in range(1, len(t)): + dp[0][j] = 0 + for i in range(1, len(s)+1): + for j in range(1, len(t)+1): + if s[i-1] == t[j-1]: + dp[i][j] = dp[i-1][j-1] + dp[i-1][j] + else: + dp[i][j] = dp[i-1][j] + return dp[-1][-1] +``` Go： From a720426f8d3ae143a9e83d823813a8e7b903496f Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 17:59:47 -0700 Subject: [PATCH 044/122] =?UTF-8?q?Update=200392.=E5=88=A4=E6=96=AD?= =?UTF-8?q?=E5=AD=90=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0392.判断子序列.md | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/problems/0392.判断子序列.md b/problems/0392.判断子序列.md index 512ebc82..9048ac44 100644 --- a/problems/0392.判断子序列.md +++ b/problems/0392.判断子序列.md @@ -144,7 +144,20 @@ Java： Python： - +```python +class Solution: + def isSubsequence(self, s: str, t: str) -> bool: + dp = [[0] * (len(t)+1) for _ in range(len(s)+1)] + for i in range(1, len(s)+1): + for j in range(1, len(t)+1): + if s[i-1] == t[j-1]: + dp[i][j] = dp[i-1][j-1] + 1 + else: + dp[i][j] = dp[i][j-1] + if dp[-1][-1] == len(s): + return True + return False +``` Go： From 426db06f7ad54ce4783774140e19446b26b3b19d Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 20:41:07 -0700 Subject: [PATCH 045/122] =?UTF-8?q?Update=200583.=E4=B8=A4=E4=B8=AA?= =?UTF-8?q?=E5=AD=97=E7=AC=A6=E4=B8=B2=E7=9A=84=E5=88=A0=E9=99=A4=E6=93=8D?= =?UTF-8?q?=E4=BD=9C.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0583.两个字符串的删除操作.md | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/problems/0583.两个字符串的删除操作.md b/problems/0583.两个字符串的删除操作.md index cd550d65..0b32d129 100644 --- a/problems/0583.两个字符串的删除操作.md +++ b/problems/0583.两个字符串的删除操作.md @@ -107,7 +107,22 @@ Java： Python： - +```python +class Solution: + def minDistance(self, word1: str, word2: str) -> int: + dp = [[0] * (len(word2)+1) for _ in range(len(word1)+1)] + for i in range(len(word1)+1): + dp[i][0] = i + for j in range(len(word2)+1): + dp[0][j] = j + for i in range(1, len(word1)+1): + for j in range(1, len(word2)+1): + if word1[i-1] == word2[j-1]: + dp[i][j] = dp[i-1][j-1] + else: + dp[i][j] = min(dp[i-1][j-1] + 2, dp[i-1][j] + 1, dp[i][j-1] + 1) + return dp[-1][-1] +``` Go： From e42433ee8c69c8b1513dea6141e7449f1107b165 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 20:47:35 -0700 Subject: [PATCH 046/122] =?UTF-8?q?Update=200072.=E7=BC=96=E8=BE=91?= =?UTF-8?q?=E8=B7=9D=E7=A6=BB.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0072.编辑距离.md | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/problems/0072.编辑距离.md b/problems/0072.编辑距离.md index 824c74af..2044ac25 100644 --- a/problems/0072.编辑距离.md +++ b/problems/0072.编辑距离.md @@ -228,7 +228,22 @@ public int minDistance(String word1, String word2) { ``` Python： - +```python +class Solution: + def minDistance(self, word1: str, word2: str) -> int: + dp = [[0] * (len(word2)+1) for _ in range(len(word1)+1)] + for i in range(len(word1)+1): + dp[i][0] = i + for j in range(len(word2)+1): + dp[0][j] = j + for i in range(1, len(word1)+1): + for j in range(1, len(word2)+1): + if word1[i-1] == word2[j-1]: + dp[i][j] = dp[i-1][j-1] + else: + dp[i][j] = min(dp[i-1][j-1], dp[i-1][j], dp[i][j-1]) + 1 + return dp[-1][-1] +``` Go： ```Go From 9b3853eae2761011f82b77aa45b840482e1b472b Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 21:05:11 -0700 Subject: [PATCH 047/122] =?UTF-8?q?Update=200647.=E5=9B=9E=E6=96=87?= =?UTF-8?q?=E5=AD=90=E4=B8=B2.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0647.回文子串.md | 50 +++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/problems/0647.回文子串.md b/problems/0647.回文子串.md index 58949571..31734bbc 100644 --- a/problems/0647.回文子串.md +++ b/problems/0647.回文子串.md @@ -284,6 +284,56 @@ class Solution { Python： +> 动态规划： +```python +class Solution: + def countSubstrings(self, s: str) -> int: + dp = [[False] * len(s) for _ in range(len(s))] + result = 0 + for i in range(len(s)-1, -1, -1): #注意遍历顺序 + for j in range(i, len(s)): + if s[i] == s[j]: + if j - i <= 1: #情况一 和 情况二 + result += 1 + dp[i][j] = True + elif dp[i+1][j-1]: #情况三 + result += 1 + dp[i][j] = True + return result +``` + +> 动态规划：简洁版 +```python +class Solution: + def countSubstrings(self, s: str) -> int: + dp = [[False] * len(s) for _ in range(len(s))] + result = 0 + for i in range(len(s)-1, -1, -1): #注意遍历顺序 + for j in range(i, len(s)): + if s[i] == s[j] and (j - i <= 1 or dp[i+1][j-1]): + result += 1 + dp[i][j] = True + return result +``` + +> 双指针法： +```python +class Solution: + def countSubstrings(self, s: str) -> int: + result = 0 + for i in range(len(s)): + result += self.extend(s, i, i, len(s)) #以i为中心 + result += self.extend(s, i, i+1, len(s)) #以i和i+1为中心 + return result + + def extend(self, s, i, j, n): + res = 0 + while i >= 0 and j < n and s[i] == s[j]: + i -= 1 + j += 1 + res += 1 + return res +``` Go： ```Go From 0e25b3ce32f0f62432b0d39a1b9c67713e8d2f42 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Tue, 8 Jun 2021 21:14:40 -0700 Subject: [PATCH 048/122] =?UTF-8?q?Update=200516.=E6=9C=80=E9=95=BF?= =?UTF-8?q?=E5=9B=9E=E6=96=87=E5=AD=90=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0516.最长回文子序列.md | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/problems/0516.最长回文子序列.md b/problems/0516.最长回文子序列.md index a7dfa648..a4f0522f 100644 --- a/problems/0516.最长回文子序列.md +++ b/problems/0516.最长回文子序列.md @@ -170,7 +170,20 @@ public class Solution { Python： - +```python +class Solution: + def longestPalindromeSubseq(self, s: str) -> int: + dp = [[0] * len(s) for _ in range(len(s))] + for i in range(len(s)): + dp[i][i] = 1 + for i in range(len(s)-1, -1, -1): + for j in range(i+1, len(s)): + if s[i] == s[j]: + dp[i][j] = dp[i+1][j-1] + 2 + else: + dp[i][j] = max(dp[i+1][j], dp[i][j-1]) + return dp[0][-1] +``` Go： ```Go From 7343bb7b14cbd9ae3fc8af2c705f4f98f56f7dad Mon Sep 17 00:00:00 2001 From: SkyLazy <627770537@qq.com> Date: Wed, 9 Jun 2021 16:51:32 +0800 Subject: [PATCH 049/122] =?UTF-8?q?Update=200977.=E6=9C=89=E5=BA=8F?= =?UTF-8?q?=E6=95=B0=E7=BB=84=E7=9A=84=E5=B9=B3=E6=96=B9.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit java代码 --- problems/0977.有序数组的平方.md | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/problems/0977.有序数组的平方.md b/problems/0977.有序数组的平方.md index b5d392e6..f3e9cf38 100644 --- a/problems/0977.有序数组的平方.md +++ b/problems/0977.有序数组的平方.md @@ -98,6 +98,26 @@ public: Java： +```Java +class Solution { + public int[] sortedSquares(int[] nums) { + int right = nums.length - 1; + int left = 0; + int[] result = new int[nums.length]; + int index = result.length - 1; + while (left <= right) { + if (nums[left] * nums[left] > nums[right] * nums[right]) { + result[index--] = nums[left] * nums[left]; + ++left; + } else { + result[index--] = nums[right] * nums[right]; + --right; + } + } + return result; + } +} +``` Python： ```Python From 49b82575b40e9beff1d19c6995962ac3465da3fc Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Wed, 9 Jun 2021 23:13:21 +0800 Subject: [PATCH 050/122] =?UTF-8?q?Update=200070.=E7=88=AC=E6=A5=BC?= =?UTF-8?q?=E6=A2=AF=E5=AE=8C=E5=85=A8=E8=83=8C=E5=8C=85=E7=89=88=E6=9C=AC?= =?UTF-8?q?.md=20=E6=B7=BB=E5=8A=A0=20pyhthon3=20=E7=89=88=E6=9C=AC?= =?UTF-8?q?=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0070.爬楼梯完全背包版本.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/0070.爬楼梯完全背包版本.md b/problems/0070.爬楼梯完全背包版本.md index 69750f8f..2896ca88 100644 --- a/problems/0070.爬楼梯完全背包版本.md +++ b/problems/0070.爬楼梯完全背包版本.md @@ -147,6 +147,23 @@ class Solution { Python： +```python3 +class Solution: + def climbStairs(self, n: int) -> int: + dp = [0]*(n + 1) + dp[0] = 1 + m = 2 + # 遍历背包 + for j in range(n + 1): + # 遍历物品 + for step in range(1, m + 1): + if j >= step: + dp[j] += dp[j - step] + return dp[n] +``` + + + Go： From 33dcb8dbd3d98ad38bdb37e0d7b6a6113ded4422 Mon Sep 17 00:00:00 2001 From: Yang Date: Wed, 9 Jun 2021 15:46:57 -0400 Subject: [PATCH 051/122] =?UTF-8?q?Update=200198.=E6=89=93=E5=AE=B6?= =?UTF-8?q?=E5=8A=AB=E8=88=8D.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Java code: initialize dp array with length `nums.length` is sufficient --- problems/0198.打家劫舍.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0198.打家劫舍.md b/problems/0198.打家劫舍.md index f49857bb..63a68c36 100644 --- a/problems/0198.打家劫舍.md +++ b/problems/0198.打家劫舍.md @@ -118,7 +118,7 @@ class Solution { if (nums == null || nums.length == 0) return 0; if (nums.length == 1) return nums[0]; - int[] dp = new int[nums.length + 1]; + int[] dp = new int[nums.length]; dp[0] = nums[0]; dp[1] = Math.max(dp[0], nums[1]); for (int i = 2; i < nums.length; i++) { From 9f3990a78f7ca4719fdb2cb11f6c6a0e203c3a39 Mon Sep 17 00:00:00 2001 From: jojoo15 <75017412+jojoo15@users.noreply.github.com> Date: Wed, 9 Jun 2021 23:08:35 +0200 Subject: [PATCH 052/122] =?UTF-8?q?=E4=BC=98=E5=8C=96=201005.K=E6=AC=A1?= =?UTF-8?q?=E5=8F=96=E5=8F=8D=E5=90=8E=E6=9C=80=E5=A4=A7=E5=8C=96=E7=9A=84?= =?UTF-8?q?=E6=95=B0=E7=BB=84=E5=92=8C=20python3=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 优化 1005.K次取反后最大化的数组和 python3版本 --- problems/1005.K次取反后最大化的数组和.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/1005.K次取反后最大化的数组和.md b/problems/1005.K次取反后最大化的数组和.md index 5539aff8..387de147 100644 --- a/problems/1005.K次取反后最大化的数组和.md +++ b/problems/1005.K次取反后最大化的数组和.md @@ -133,7 +133,7 @@ class Solution: A[i] *= -1 K -= 1 if K > 0: - A[len(A) - 1] *= ((-1)**K) + A[-1] *= (-1)**K #取A最后一个数只需要写-1 return sum(A) ``` From c06f5d2ccefa01488ab457bfe0d370cac015af84 Mon Sep 17 00:00:00 2001 From: Huairuo Yang Date: Wed, 9 Jun 2021 20:08:36 -0400 Subject: [PATCH 053/122] =?UTF-8?q?=E5=88=A0=E9=99=A4=E5=A4=9A=E4=BD=99?= =?UTF-8?q?=E7=A9=BA=E6=A0=BC=E5=92=8C=E6=97=A0=E7=94=A8=E7=A9=BA=E6=A0=BC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Remove fault and redundant bracket --- problems/0151.翻转字符串里的单词.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index 63499b71..d76734e4 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -183,7 +183,7 @@ public: int end = 0; // 反转的单词在字符串里终止位置 bool entry = false; // 标记枚举字符串的过程中是否已经进入了单词区间 for (int i = 0; i < s.size(); i++) { // 开始反转单词 - if ((!entry))) { + if (!entry) { start = i; // 确定单词起始位置 entry = true; // 进入单词区间 } @@ -380,4 +380,4 @@ func reverse(b *[]byte, left, right int) { * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频：[代码随想录](https://space.bilibili.com/525438321) * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ) -

\ No newline at end of file +
From f19cc3ddd4c4fb347761678d94e308131ff520b9 Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Thu, 10 Jun 2021 08:14:17 +0800 Subject: [PATCH 054/122] =?UTF-8?q?0452.=E7=94=A8=E6=9C=80=E5=B0=91?= =?UTF-8?q?=E6=95=B0=E9=87=8F=E7=9A=84=E7=AE=AD=E5=BC=95=E7=88=86=E6=B0=94?= =?UTF-8?q?=E7=90=83=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0452.用最少数量的箭引爆气球.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/0452.用最少数量的箭引爆气球.md b/problems/0452.用最少数量的箭引爆气球.md index 9b0cc925..bb3ebbdc 100644 --- a/problems/0452.用最少数量的箭引爆气球.md +++ b/problems/0452.用最少数量的箭引爆气球.md @@ -175,7 +175,24 @@ class Solution: Go： +Javascript: +```Javascript +var findMinArrowShots = function(points) { + points.sort((a, b) => { + return a[0] - b[0] + }) + let result = 1 + for(let i = 1; i < points.length; i++) { + if(points[i][0] > points[i - 1][1]) { + result++ + } else { + points[i][1] = Math.min(points[i - 1][1], points[i][1]) + } + } + return result +}; +``` ----------------------- From 48ac8ec77c91d4f377ea3fc912da2457854ddada Mon Sep 17 00:00:00 2001 From: liulei <718356979@qq.com> Date: Thu, 10 Jun 2021 09:45:23 +0800 Subject: [PATCH 055/122] =?UTF-8?q?update=20=E8=83=8C=E5=8C=85=E7=90=86?= =?UTF-8?q?=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2=20java?= =?UTF-8?q?=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 28 +++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index 1d3f8b03..e85d31b4 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -211,9 +211,35 @@ int main() { ## 其他语言版本 - Java： +```java + public static void main(String[] args) { + int[] weight = {1, 3, 4}; + int[] value = {15, 20, 30}; + int bagWight = 4; + testWeightBagProblem(weight, value, bagWight); + } + + public static void testWeightBagProblem(int[] weight, int[] value, int bagWeight){ + int wLen = weight.length; + //定义dp数组：dp[j]表示背包容量为j时，能获得的最大价值 + int[] dp = new int[bagWeight + 1]; + //遍历顺序：先遍历物品，再遍历背包容量 + for (int i = 0; i < wLen; i++){ + for (int j = bagWeight; j >= weight[i]; j--){ + dp[j] = Math.max(dp[j], dp[j - weight[i]] + value[i]); + } + } + //打印dp数组 + for (int j = 0; j <= bagWeight; j++){ + System.out.print(dp[j] + " "); + } + } +``` + + + Python： From 96e0d91f0bb429851e0280bec39b21cafb69eed9 Mon Sep 17 00:00:00 2001 From: youngyangyang04 <826123027@qq.com> Date: Thu, 10 Jun 2021 11:10:41 +0800 Subject: [PATCH 056/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E6=AF=8F=E6=97=A5?= =?UTF-8?q?=E6=B8=A9=E5=BA=A6?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- README.md | 5 +- problems/0739.每日温度.md | 196 ++++++++++++++++++++++++++++++++++ 2 files changed, 200 insertions(+), 1 deletion(-) create mode 100644 problems/0739.每日温度.md diff --git a/README.md b/README.md index 4fa9100d..daef7c02 100644 --- a/README.md +++ b/README.md @@ -384,9 +384,12 @@ 54. [动态规划：最长回文子序列](./problems/0516.最长回文子序列.md) 55. [动态规划总结篇](./problems/动态规划总结篇.md) - （持续更新中....） +## 单调栈 + +1. [每日温度](./problems/0739.每日温度.md) + ## 图论 ## 十大排序 diff --git a/problems/0739.每日温度.md b/problems/0739.每日温度.md new file mode 100644 index 00000000..516d068d --- /dev/null +++ b/problems/0739.每日温度.md @@ -0,0 +1,196 @@ + +

+ + + + +

+

欢迎大家参与本项目，贡献其他语言版本的代码，拥抱开源，让更多学习算法的小伙伴们收益！

+ +# 739. 每日温度 + + +https://leetcode-cn.com/problems/daily-temperatures/ + +请根据每日 气温 列表，重新生成一个列表。对应位置的输出为：要想观测到更高的气温，至少需要等待的天数。如果气温在这之后都不会升高，请在该位置用 0 来代替。 + +例如，给定一个列表 temperatures = [73, 74, 75, 71, 69, 72, 76, 73]，你的输出应该是 [1, 1, 4, 2, 1, 1, 0, 0]。 + +提示：气温 列表长度的范围是 [1, 30000]。每个气温的值的均为华氏度，都是在 [30, 100] 范围内的整数。 + + +## 思路 + +首先想到的当然是暴力解法，两层for循环，把至少需要等待的天数就搜出来了。时间复杂度是O(n^2) + +那么接下来在来看看使用单调栈的解法。 + +那有同学就问了，我怎么能想到用单调栈呢？ 什么时候用单调栈呢？ + +**通常是一维数组，要寻找任一个元素的右边或者左边第一个比自己大或者小的元素的位置，此时我们就要想到可以用单调栈了**。 + +时间复杂度为O(n)。 + +例如本题其实就是找找到一个元素右边第一个比自己大的元素。 + +此时就应该想到用单调栈了。 + +那么单调栈的原理是什么呢？为什么时间复杂度是O(n)就可以找到每一个元素的右边第一个比它大的元素位置呢？ + +单调栈的本质是空间换时间，因为在遍历的过程中需要用一个栈来记录右边第一个比当前元素的元素，优点是只需要遍历一次。 + + +在使用单调栈的时候首先要明确如下几点： + +1. 单调栈里存放的元素是什么？ + +单调栈里只需要存放元素的下标i就可以了，如果需要使用对应的元素，直接T[i]就可以获取。 + +2. 单调栈里元素是递增呢？ 还是递减呢？ + +**注意一下顺序为 从栈头到栈底的顺序**，因为单纯的说从左到右或者从前到后，不说栈头朝哪个方向的话，大家一定会越看越懵。 + + +这里我们要使用递增循序（再强调一下是指从栈头到栈底的顺序），因为只有递增的时候，加入一个元素i，才知道栈顶元素在数组中右面第一个比栈顶元素大的元素是i。 + +文字描述理解起来有点费劲，接下来我画了一系列的图，来讲解单调栈的工作过程。 + +使用单调栈主要有三个判断条件。 + +* 当前遍历的元素T[i]小于栈顶元素T[st.top()]的情况 +* 当前遍历的元素T[i]等于栈顶元素T[st.top()]的情况 +* 当前遍历的元素T[i]大于栈顶元素T[st.top()]的情况 + +**把这三种情况分析清楚了，也就理解透彻了**。 + +接下来我们用temperatures = [73, 74, 75, 71, 71, 72, 76, 73]为例来逐步分析，输出应该是 [1, 1, 4, 2, 1, 1, 0, 0]。 + +首先先将第一个遍历元素加入单调栈 +![739.每日温度1](https://img-blog.csdnimg.cn/20210219124434172.jpg) + +加入T[1] = 74，因为T[1] > T[0]（当前遍历的元素T[i]大于栈顶元素T[st.top()]的情况），而我们要保持一个递增单调栈（从栈头到栈底），所以将T[0]弹出，T[1]加入，此时result数组可以记录了，result[0] = 1，即T[0]右面第一个比T[0]大的元素是T[1]。 +![739.每日温度2](https://img-blog.csdnimg.cn/20210219124504299.jpg) + +加入T[2]，同理，T[1]弹出 + +![739.每日温度3](https://img-blog.csdnimg.cn/20210219124527361.jpg) + +加入T[3]，T[3] < T[2] （当前遍历的元素T[i]小于栈顶元素T[st.top()]的情况），加T[3]加入单调栈。 + +![739.每日温度4](https://img-blog.csdnimg.cn/20210219124610761.jpg) + +加入T[4]，T[4] == T[3] （当前遍历的元素T[i]等于栈顶元素T[st.top()]的情况），此时依然要加入栈，不用计算距离，因为我们要求的是右面第一个大于本元素的位置，而不是大于等于！ +![739.每日温度5](https://img-blog.csdnimg.cn/20210219124633444.jpg) + +加入T[5]，T[5] > T[4] （当前遍历的元素T[i]大于栈顶元素T[st.top()]的情况），将T[4]弹出，同时计算距离，更新result +![739.每日温度6](https://img-blog.csdnimg.cn/20210219124700567.jpg) + +T[4]弹出之后， T[5] > T[3] （当前遍历的元素T[i]大于栈顶元素T[st.top()]的情况），将T[3]继续弹出，同时计算距离，更新result +![739.每日温度7](https://img-blog.csdnimg.cn/20210219124726613.jpg) + +直到发现T[5]小于T[st.top()]，终止弹出，将T[5]加入单调栈 +![739.每日温度8](https://img-blog.csdnimg.cn/20210219124807715.jpg) + +加入T[6]，同理，需要将栈里的T[5]，T[2]弹出 +![739.每日温度9](https://img-blog.csdnimg.cn/2021021912483374.jpg) + +同理，继续弹出 +![739.每日温度10](https://img-blog.csdnimg.cn/2021021912490098.jpg) + +此时栈里只剩下了T[6] + +![739.每日温度11](https://img-blog.csdnimg.cn/20210219124930156.jpg) + +加入T[7]， T[7] < T[6] 直接入栈，这就是最后的情况，result数组也更新完了。 +![739.每日温度12](https://img-blog.csdnimg.cn/20210219124957216.jpg) + + +此时有同学可能就疑惑了，那result[6] , result[7]怎么没更新啊，元素也一直在栈里。 + +其实定义result数组的时候，就应该直接初始化为0，如果result没有更新，说明这个元素右面没有更大的了，也就是为0。 + +以上在图解的时候，已经把，这三种情况都做了详细的分析。 + +* 情况一：当前遍历的元素T[i]小于栈顶元素T[st.top()]的情况 +* 情况二：当前遍历的元素T[i]等于栈顶元素T[st.top()]的情况 +* 情况三：当前遍历的元素T[i]大于栈顶元素T[st.top()]的情况 + +C++代码如下： + +```C++ +// 版本一 +class Solution { +public: + vector dailyTemperatures(vector& T) { + // 递减栈 + stack st; + vector result(T.size(), 0); + st.push(0); + for (int i = 1; i < T.size(); i++) { + if (T[i] < T[st.top()]) { // 情况一 + st.push(i); + } else if (T[i] == T[st.top()]) { // 情况二 + st.push(i); + } else { + while (!st.empty() && T[i] > T[st.top()]) { // 情况三 + result[st.top()] = i - st.top(); + st.pop(); + } + st.push(i); + } + } + return result; + } +}; +``` + +**建议一开始 都把每种情况分析好，不要上来看简短的代码，关键逻辑都被隐藏了**。 + +精简代码如下： + +```C++ +// 版本二 +class Solution { +public: + vector dailyTemperatures(vector& T) { + stack st; // 递减栈 + vector result(T.size(), 0); + st.push(0); + for (int i = 1; i < T.size(); i++) { + while (!st.empty() && T[i] > T[st.top()]) { // 注意栈不能为空 + result[st.top()] = i - st.top(); + st.pop(); + } + st.push(i); + + } + return result; + } +}; +``` +* 时间复杂度：O(n) +* 空间复杂度：O(n) + +精简的代码是直接把情况一二三都合并到了一起，其实这种代码精简是精简，但思路不是很清晰。 + +建议大家把情况一二三想清楚了，先写出版本一的代码，然后在其基础上在做精简！ + + +## 其他语言版本 + + +Java： + +Python： + +Go： + + + + +----------------------- +* 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) +* B站视频：[代码随想录](https://space.bilibili.com/525438321) +* 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ) +
+ From da57f5123bb37017970cad1fc4c0ab19ad7c9dd7 Mon Sep 17 00:00:00 2001 From: youngyangyang04 <826123027@qq.com> Date: Thu, 10 Jun 2021 11:10:56 +0800 Subject: [PATCH 057/122] Update --- problems/哈希表总结.md | 46 +++++++++++++------------------------ 1 file changed, 16 insertions(+), 30 deletions(-) diff --git a/problems/哈希表总结.md b/problems/哈希表总结.md index a578a203..c3fbde2b 100644 --- a/problems/哈希表总结.md +++ b/problems/哈希表总结.md @@ -9,11 +9,10 @@ > 哈希表总结篇如约而至 -哈希表系列也是早期讲解的时候没有写总结篇，所以选个周末给补上，毕竟「代码随想录」的系列怎么能没有总结篇呢[机智]。 # 哈希表理论基础 -在[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/g8N6WmoQmsCUw3_BaWxHZA)中，我们介绍了哈希表的基础理论知识，不同于枯燥的讲解，这里介绍了都是对刷题有帮助的理论知识点。 +在[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/RSUANESA_tkhKhYe3ZR8Jg)中，我们介绍了哈希表的基础理论知识，不同于枯燥的讲解，这里介绍了都是对刷题有帮助的理论知识点。 **一般来说哈希表都是用来快速判断一个元素是否出现集合里**。 @@ -29,7 +28,7 @@ * set（集合） * map（映射） -在C++语言中，set 和 map 都分别提供了三种数据结构，每种数据结构的底层实现和用途都有所不同，在[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/g8N6WmoQmsCUw3_BaWxHZA)中我给出了详细分析，这一知识点很重要！ +在C++语言中，set 和 map 都分别提供了三种数据结构，每种数据结构的底层实现和用途都有所不同，在[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/RSUANESA_tkhKhYe3ZR8Jg)中我给出了详细分析，这一知识点很重要！ 例如什么时候用std::set，什么时候用std::multiset，什么时候用std::unordered_set，都是很有考究的。 @@ -41,13 +40,13 @@ 一些应用场景就是为数组量身定做的。 -在[哈希表：有效的字母异位词](https://mp.weixin.qq.com/s/vM6OszkM6L1Mx2Ralm9Dig)中，我们提到了数组就是简单的哈希表，但是数组的大小是受限的！ +在[242.有效的字母异位词](https://mp.weixin.qq.com/s/ffS8jaVFNUWyfn_8T31IdA)中，我们提到了数组就是简单的哈希表，但是数组的大小是受限的！ 这道题目包含小写字母，那么使用数组来做哈希最合适不过。 -在[哈希表：赎金信](https://mp.weixin.qq.com/s/sYZIR4dFBrw_lr3eJJnteQ)中同样要求只有小写字母，那么就给我们浓浓的暗示，用数组！ +在[383.赎金信](https://mp.weixin.qq.com/s/qAXqv--UERmiJNNpuphOUQ)中同样要求只有小写字母，那么就给我们浓浓的暗示，用数组！ -本题和[哈希表：有效的字母异位词](https://mp.weixin.qq.com/s/vM6OszkM6L1Mx2Ralm9Dig)很像，[哈希表：有效的字母异位词](https://mp.weixin.qq.com/s/vM6OszkM6L1Mx2Ralm9Dig)是求 字符串a 和 字符串b 是否可以相互组成，在[哈希表：赎金信](https://mp.weixin.qq.com/s/sYZIR4dFBrw_lr3eJJnteQ)中是求字符串a能否组成字符串b，而不用管字符串b 能不能组成字符串a。 +本题和[242.有效的字母异位词](https://mp.weixin.qq.com/s/ffS8jaVFNUWyfn_8T31IdA)很像，[242.有效的字母异位词](https://mp.weixin.qq.com/s/ffS8jaVFNUWyfn_8T31IdA)是求 字符串a 和 字符串b 是否可以相互组成，在[383.赎金信](https://mp.weixin.qq.com/s/qAXqv--UERmiJNNpuphOUQ)中是求字符串a能否组成字符串b，而不用管字符串b 能不能组成字符串a。 一些同学可能想，用数组干啥，都用map不就完事了。 @@ -56,7 +55,7 @@ ## set作为哈希表 -在[哈希表：两个数组的交集](https://mp.weixin.qq.com/s/N9iqAchXreSVW7zXUS4BVA)中我们给出了什么时候用数组就不行了，需要用set。 +在[349. 两个数组的交集](https://mp.weixin.qq.com/s/aMSA5zrp3jJcLjuSB0Es2Q)中我们给出了什么时候用数组就不行了，需要用set。 这道题目没有限制数值的大小，就无法使用数组来做哈希表了。 @@ -67,7 +66,7 @@ 所以此时一样的做映射的话，就可以使用set了。 -关于set，C++ 给提供了如下三种可用的数据结构：（详情请看[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/g8N6WmoQmsCUw3_BaWxHZA)） +关于set，C++ 给提供了如下三种可用的数据结构：（详情请看[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/RSUANESA_tkhKhYe3ZR8Jg)） * std::set * std::multiset @@ -75,12 +74,12 @@ std::set和std::multiset底层实现都是红黑树，std::unordered_set的底层实现是哈希， 使用unordered_set 读写效率是最高的，本题并不需要对数据进行排序，而且还不要让数据重复，所以选择unordered_set。 -在[哈希表：快乐数](https://mp.weixin.qq.com/s/G4Q2Zfpfe706gLK7HpZHpA)中，我们再次使用了unordered_set来判断一个数是否重复出现过。 +在[202.快乐数](https://mp.weixin.qq.com/s/n5q0ujxxrjQS3xuh3dgqBQ)中，我们再次使用了unordered_set来判断一个数是否重复出现过。 ## map作为哈希表 -在[哈希表：两数之和](https://mp.weixin.qq.com/s/uVAtjOHSeqymV8FeQbliJQ)中map正式登场。 +在[1.两数之和](https://mp.weixin.qq.com/s/vaMsLnH-f7_9nEK4Cuu3KQ)中map正式登场。 来说一说：使用数组和set来做哈希法的局限。 @@ -89,7 +88,7 @@ std::set和std::multiset底层实现都是红黑树，std::unordered_set的底 map是一种``的结构，本题可以用key保存数值，用value在保存数值所在的下表。所以使用map最为合适。 -C++提供如下三种map：：（详情请看[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/g8N6WmoQmsCUw3_BaWxHZA)） +C++提供如下三种map：：（详情请看[关于哈希表，你该了解这些！](https://mp.weixin.qq.com/s/RSUANESA_tkhKhYe3ZR8Jg)） * std::map * std::multimap @@ -97,21 +96,21 @@ C++提供如下三种map：：（详情请看[关于哈希表，你该了解这 std::unordered_map 底层实现为哈希，std::map 和std::multimap 的底层实现是红黑树。 -同理，std::map 和std::multimap 的key也是有序的（这个问题也经常作为面试题，考察对语言容器底层的理解），[哈希表：两数之和](https://mp.weixin.qq.com/s/uVAtjOHSeqymV8FeQbliJQ)中并不需要key有序，选择std::unordered_map 效率更高！ +同理，std::map 和std::multimap 的key也是有序的（这个问题也经常作为面试题，考察对语言容器底层的理解），[1.两数之和](https://mp.weixin.qq.com/s/vaMsLnH-f7_9nEK4Cuu3KQ)中并不需要key有序，选择std::unordered_map 效率更高！ -在[哈希表：四数相加II](https://mp.weixin.qq.com/s/Ue8pKKU5hw_m-jPgwlHcbA)中我们提到了其实需要哈希的地方都能找到map的身影。 +在[454.四数相加](https://mp.weixin.qq.com/s/12g_w6RzHuEpFts1pT6BWw)中我们提到了其实需要哈希的地方都能找到map的身影。 -本题咋眼一看好像和[18. 四数之](https://mp.weixin.qq.com/s/r5cgZFu0tv4grBAexdcd8A)，[15.三数之和](https://mp.weixin.qq.com/s/nQrcco8AZJV1pAOVjeIU_g)差不多，其实差很多！ +本题咋眼一看好像和[18. 四数之和](https://mp.weixin.qq.com/s/SBU3THi1Kv6Sar7htqCB2Q)，[15.三数之和](https://mp.weixin.qq.com/s/QfTNEByq1YlNSXRKEumwHg)差不多，其实差很多！ -**关键差别是本题为四个独立的数组，只要找到A[i] + B[j] + C[k] + D[l] = 0就可以，不用考虑重复问题，而[18. 四数之和](https://mp.weixin.qq.com/s/nQrcco8AZJV1pAOVjeIU_g)，[15.三数之和](https://mp.weixin.qq.com/s/r5cgZFu0tv4grBAexdcd8A)是一个数组（集合）里找到和为0的组合，可就难很多了！** +**关键差别是本题为四个独立的数组，只要找到A[i] + B[j] + C[k] + D[l] = 0就可以，不用考虑重复问题，而[18. 四数之和](https://mp.weixin.qq.com/s/SBU3THi1Kv6Sar7htqCB2Q)，[15.三数之和](https://mp.weixin.qq.com/s/QfTNEByq1YlNSXRKEumwHg)是一个数组（集合）里找到和为0的组合，可就难很多了！** 用哈希法解决了两数之和，很多同学会感觉用哈希法也可以解决三数之和，四数之和。 其实是可以解决，但是非常麻烦，需要去重导致代码效率很低。 -在[哈希表：解决了两数之和，那么能解决三数之和么？](https://mp.weixin.qq.com/s/r5cgZFu0tv4grBAexdcd8A)中我给出了哈希法和双指针两个解法，大家就可以体会到，使用哈希法还是比较麻烦的。 +在[15.三数之和](https://mp.weixin.qq.com/s/QfTNEByq1YlNSXRKEumwHg)中我给出了哈希法和双指针两个解法，大家就可以体会到，使用哈希法还是比较麻烦的。 -所以[18. 四数之](https://mp.weixin.qq.com/s/r5cgZFu0tv4grBAexdcd8A)，[15.三数之和](https://mp.weixin.qq.com/s/nQrcco8AZJV1pAOVjeIU_g)都推荐使用双指针法！ +所以18. 四数之和，15.三数之和都推荐使用双指针法！ # 总结 @@ -127,19 +126,6 @@ std::unordered_map 底层实现为哈希，std::map 和std::multimap 的底层 -## 其他语言版本 - - -Java： - - -Python： - - -Go： - - - ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From ed7e252e14ce9d2ba151d8080d7098e428350233 Mon Sep 17 00:00:00 2001 From: KailokFung Date: Thu, 10 Jun 2021 11:21:03 +0800 Subject: [PATCH 058/122] =?UTF-8?q?feat(977):=20=E6=96=B0=E5=A2=9Ejava?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0977.有序数组的平方.md | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/problems/0977.有序数组的平方.md b/problems/0977.有序数组的平方.md index b5d392e6..d28a9427 100644 --- a/problems/0977.有序数组的平方.md +++ b/problems/0977.有序数组的平方.md @@ -96,9 +96,27 @@ public: ## 其他语言版本 - Java： +```java +class Solution { + public int[] sortedSquares(int[] nums) { + int l = 0; + int r = nums.length - 1; + int[] res = new int[nums.length]; + int j = nums.length - 1; + while(l <= r){ + if(nums[l] * nums[l] > nums[r] * nums[r]){ + res[j--] = nums[l] * nums[l++]; + }else{ + res[j--] = nums[r] * nums[r--]; + } + } + return res; + } +} +``` + Python： ```Python class Solution: From e735356e6dfc8ed17463313941b5dfc2bf37dd7b Mon Sep 17 00:00:00 2001 From: zhangzw Date: Thu, 10 Jun 2021 13:49:22 +0800 Subject: [PATCH 059/122] =?UTF-8?q?update0322.=E9=9B=B6=E9=92=B1=E5=85=91?= =?UTF-8?q?=E6=8D=A2=20Go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0322.零钱兑换.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/problems/0322.零钱兑换.md b/problems/0322.零钱兑换.md index 2c9ff8cf..cc288593 100644 --- a/problems/0322.零钱兑换.md +++ b/problems/0322.零钱兑换.md @@ -226,11 +226,11 @@ func coinChange1(coins []int, amount int) int { for i := 0; i < len(coins); i++ { // 遍历背包 for j := coins[i]; j <= amount; j++ { - //if dp[j-coins[i]] != math.MaxInt32 { + if dp[j-coins[i]] != math.MaxInt32 { // 推导公式 dp[j] = min(dp[j], dp[j-coins[i]]+1) - fmt.Println(dp,j,i) - //} + //fmt.Println(dp,j,i) + } } } // 没找到能装满背包的, 就返回-1 From da8f3c92a447ec924b9f9ae5bc182ff2681bc51b Mon Sep 17 00:00:00 2001 From: lichuanming <1465802096@qq.com> Date: Thu, 10 Jun 2021 16:30:39 +0800 Subject: [PATCH 060/122] =?UTF-8?q?0739=20=E5=8D=95=E8=B0=83=E6=A0=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0739.每日温度.md | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/problems/0739.每日温度.md b/problems/0739.每日温度.md index 516d068d..1f91e42a 100644 --- a/problems/0739.每日温度.md +++ b/problems/0739.每日温度.md @@ -180,7 +180,36 @@ public: Java： - +```java +/** + * 单调栈，栈内顺序要么从大到小 要么从小到大,本题从大到笑 + *

+ * 入站元素要和当前栈内栈首元素进行比较 + * 若大于栈首则 则与元素下标做差 + * 若大于等于则放入 + * + * @param temperatures + * @return + */ + public static int[] dailyTemperatures(int[] temperatures) { + Stack stack = new Stack<>(); + int[] res = new int[temperatures.length]; + for (int i = 0; i < temperatures.length; i++) { + /** + * 取出下标进行元素值的比较 + */ + while (!stack.isEmpty() && temperatures[i] > temperatures[stack.peek()]) { + int preIndex = stack.pop(); + res[preIndex] = i - preIndex; + } + /** + * 注意 放入的是元素位置 + */ + stack.push(i); + } + return res; + } +``` Python： Go： From 7b6223f7d911cf4be160b60e5405efad8e07028c Mon Sep 17 00:00:00 2001 From: LiangDazhu <42199191+LiangDazhu@users.noreply.github.com> Date: Fri, 11 Jun 2021 00:33:03 +0800 Subject: [PATCH 061/122] =?UTF-8?q?Update=200070.=E7=88=AC=E6=A5=BC?= =?UTF-8?q?=E6=A2=AF=E5=AE=8C=E5=85=A8=E8=83=8C=E5=8C=85=E7=89=88=E6=9C=AC?= =?UTF-8?q?.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Added python version code --- problems/0070.爬楼梯完全背包版本.md | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/problems/0070.爬楼梯完全背包版本.md b/problems/0070.爬楼梯完全背包版本.md index 9fc33bb8..90c9a8c0 100644 --- a/problems/0070.爬楼梯完全背包版本.md +++ b/problems/0070.爬楼梯完全背包版本.md @@ -146,7 +146,18 @@ class Solution { ``` Python： - +```python +class Solution: + def climbStairs(self, n: int) -> int: + m = 2 + dp = [0] * (n + 1) + dp[0] = 1 + for i in range(n + 1): + for j in range(1, m + 1): + if i >= j: + dp[i] += dp[i - j] + return dp[-1] +``` Go： ```go From 5b268b787f0f07e926013c7246469244b95d0169 Mon Sep 17 00:00:00 2001 From: NevS <1173325467@qq.com> Date: Fri, 11 Jun 2021 20:59:12 +0800 Subject: [PATCH 062/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20=E5=89=91=E6=8C=87?= =?UTF-8?q?Offer05.=E6=9B=BF=E6=8D=A2=E7=A9=BA=E6=A0=BC=20go=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/剑指Offer05.替换空格.md | 47 ++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md index 794f9ac5..a4c0149f 100644 --- a/problems/剑指Offer05.替换空格.md +++ b/problems/剑指Offer05.替换空格.md @@ -154,7 +154,54 @@ Python： Go： +```go +// 遍历添加 +func replaceSpace(s string) string { + b := []byte(s) + result := make([]byte, 0) + for i := 0; i < len(b); i++ { + if b[i] == ' ' { + result = append(result, []byte("%20")...) + } else { + result = append(result, b[i]) + } + } + return string(result) +} +// 原地修改 +func replaceSpace(s string) string { + b := []byte(s) + length := len(b) + spaceCount := 0 + // 计算空格数量 + for _, v := range b { + if v == ' ' { + spaceCount++ + } + } + // 扩展原有切片 + resizeCount := spaceCount * 2 + tmp := make([]byte, resizeCount) + b = append(b, tmp...) + i := length - 1 + j := len(b) - 1 + for i >= 0 { + if b[i] != ' ' { + b[j] = b[i] + i-- + j-- + } else { + b[j] = '0' + b[j-1] = '2' + b[j-2] = '%' + i-- + j = j - 3 + } + } + return string(b) +} +``` From fde1d0230871a5b16c65123d14581d941d8ba83e Mon Sep 17 00:00:00 2001 From: Yang Date: Fri, 11 Jun 2021 16:16:29 -0400 Subject: [PATCH 063/122] =?UTF-8?q?Update=200718.=E6=9C=80=E9=95=BF?= =?UTF-8?q?=E9=87=8D=E5=A4=8D=E5=AD=90=E6=95=B0=E7=BB=84.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add java solution --- problems/0718.最长重复子数组.md | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/problems/0718.最长重复子数组.md b/problems/0718.最长重复子数组.md index 204a513b..bef616d3 100644 --- a/problems/0718.最长重复子数组.md +++ b/problems/0718.最长重复子数组.md @@ -154,7 +154,25 @@ public: Java： - +```java +class Solution { + public int findLength(int[] nums1, int[] nums2) { + int result = 0; + int[][] dp = new int[nums1.length + 1][nums2.length + 1]; + + for (int i = 1; i < nums1.length + 1; i++) { + for (int j = 1; j < nums2.length + 1; j++) { + if (nums1[i - 1] == nums2[j - 1]) { + dp[i][j] = dp[i - 1][j - 1] + 1; + max = Math.max(max, dp[i][j]); + } + } + } + + return result; + } +} +``` Python： From fd2dfc4c0139d3296470271c5b1e0bd9af1303ba Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Sat, 12 Jun 2021 10:43:17 +0800 Subject: [PATCH 064/122] =?UTF-8?q?Update=200279.=E5=AE=8C=E5=85=A8?= =?UTF-8?q?=E5=B9=B3=E6=96=B9=E6=95=B0.md=20=E6=B7=BB=E5=8A=A0=20python3?= =?UTF-8?q?=20=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0279.完全平方数.md | 34 +++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/problems/0279.完全平方数.md b/problems/0279.完全平方数.md index 8d8b161c..60d6d165 100644 --- a/problems/0279.完全平方数.md +++ b/problems/0279.完全平方数.md @@ -26,7 +26,7 @@ 输入：n = 13 输出：2 解释：13 = 4 + 9 -  + 提示： * 1 <= n <= 10^4 @@ -184,6 +184,38 @@ class Solution { Python： +```python3 +class Solution: + def numSquares(self, n: int) -> int: + '''版本一''' + # 初始化 + nums = [i**2 for i in range(1, n + 1) if i**2 <= n] + dp = [10**4]*(n + 1) + dp[0] = 0 + # 遍历背包 + for j in range(1, n + 1): + # 遍历物品 + for num in nums: + if j >= num: + dp[j] = min(dp[j], dp[j - num] + 1) + return dp[n] + + def numSquares1(self, n: int) -> int: + '''版本二''' + # 初始化 + nums = [i**2 for i in range(1, n + 1) if i**2 <= n] + dp = [10**4]*(n + 1) + dp[0] = 0 + # 遍历物品 + for num in nums: + # 遍历背包 + for j in range(num, n + 1) + dp[j] = min(dp[j], dp[j - num] + 1) + return dp[n] +``` + + + Go： ```go From 362a8947f04cbca1ceed2ad2dac392dd95ca81fb Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Sat, 12 Jun 2021 11:08:35 +0800 Subject: [PATCH 065/122] =?UTF-8?q?Update=200322.=E9=9B=B6=E9=92=B1?= =?UTF-8?q?=E5=85=91=E6=8D=A2.md=20=E6=B7=BB=E5=8A=A0=20python3=20?= =?UTF-8?q?=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0322.零钱兑换.md | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/problems/0322.零钱兑换.md b/problems/0322.零钱兑换.md index cc288593..cf537088 100644 --- a/problems/0322.零钱兑换.md +++ b/problems/0322.零钱兑换.md @@ -35,7 +35,7 @@ 示例 5： 输入：coins = [1], amount = 2 输出：2 -  + 提示： * 1 <= coins.length <= 12 @@ -209,6 +209,36 @@ class Solution { Python： +```python3 +class Solution: + def coinChange(self, coins: List[int], amount: int) -> int: + '''版本一''' + # 初始化 + dp = [amount + 1]*(amount + 1) + dp[0] = 0 + # 遍历物品 + for coin in coins: + # 遍历背包 + for j in range(coin, amount + 1): + dp[j] = min(dp[j], dp[j - coin] + 1) + return dp[amount] if dp[amount] < amount + 1 else -1 + + def coinChange1(self, coins: List[int], amount: int) -> int: + '''版本二''' + # 初始化 + dp = [amount + 1]*(amount + 1) + dp[0] = 0 + # 遍历物品 + for j in range(1, amount + 1): + # 遍历背包 + for coin in coins: + if j >= coin: + dp[j] = min(dp[j], dp[j - coin] + 1) + return dp[amount] if dp[amount] < amount + 1 else -1 +``` + + + Go： ```go From 1c427ed82a095fb7e632c7a3b89ac2e1ba1255f6 Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Sat, 12 Jun 2021 12:06:27 +0800 Subject: [PATCH 066/122] =?UTF-8?q?Update=200139.=E5=8D=95=E8=AF=8D?= =?UTF-8?q?=E6=8B=86=E5=88=86.md=20=E6=B7=BB=E5=8A=A0=20python3=20?= =?UTF-8?q?=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0139.单词拆分.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/0139.单词拆分.md b/problems/0139.单词拆分.md index aa729e02..b6a6242e 100644 --- a/problems/0139.单词拆分.md +++ b/problems/0139.单词拆分.md @@ -252,6 +252,23 @@ class Solution { Python： +```python3 +class Solution: + def wordBreak(self, s: str, wordDict: List[str]) -> bool: + '''排列''' + dp = [False]*(len(s) + 1) + dp[0] = True + # 遍历背包 + for j in range(1, len(s) + 1): + # 遍历单词 + for word in wordDict: + if j >= len(word): + dp[j] = dp[j] or (dp[j - len(word)] and word == s[j - len(word):j]) + return dp[len(s)] +``` + + + Go： ```Go From ecf5ff1dc832b028e377d4afed3bfbf5f6317573 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 12 Jun 2021 14:24:04 +0800 Subject: [PATCH 067/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=EF=BC=9A=E4=BB=A5=E4=B8=BA=E4=BD=BF=E7=94=A8=E4=BA=86?= =?UTF-8?q?=E9=80=92=E5=BD=92=EF=BC=8C=E5=85=B6=E5=AE=9E=E8=BF=98=E9=9A=90?= =?UTF-8?q?=E8=97=8F=E7=9D=80=E5=9B=9E=E6=BA=AF=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 二叉树：以为使用了递归，其实还隐藏着回溯 go版本 --- problems/二叉树中递归带着回溯.md | 104 +++++++++++++++++++++ 1 file changed, 104 insertions(+) diff --git a/problems/二叉树中递归带着回溯.md b/problems/二叉树中递归带着回溯.md index aede1831..8014d6e1 100644 --- a/problems/二叉树中递归带着回溯.md +++ b/problems/二叉树中递归带着回溯.md @@ -336,6 +336,110 @@ class Solution: ``` Go： +100.相同的树 +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func isSameTree(p *TreeNode, q *TreeNode) bool { + switch { + case p == nil && q == nil: + return true + case p == nil || q == nil: + fmt.Println(p,q) + fallthrough + case p.Val != q.Val: + return false + } + return isSameTree(p.Left, q.Left) && isSameTree(p.Right, q.Right) +} +``` + +257.二叉的所有路径 +> 递归法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func binaryTreePaths(root *TreeNode) []string { + var result []string + traversal(root,&result,"") + return result +} +func traversal(root *TreeNode,result *[]string,pathStr string){ + //判断是否为第一个元素 + if len(pathStr)!=0{ + pathStr=pathStr+"->"+strconv.Itoa(root.Val) + }else{ + pathStr=strconv.Itoa(root.Val) + } + //判断是否为叶子节点 + if root.Left==nil&&root.Right==nil{ + *result=append(*result,pathStr) + return + } + //左右 + if root.Left!=nil{ + traversal(root.Left,result,pathStr) + } + if root.Right!=nil{ + traversal(root.Right,result,pathStr) + } +} +``` + +> 回溯法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func binaryTreePaths(root *TreeNode) []string { + var result []string + var path []int + traversal(root,&result,&path) + return result +} +func traversal(root *TreeNode,result *[]string,path *[]int){ + *path=append(*path,root.Val) + //判断是否为叶子节点 + if root.Left==nil&&root.Right==nil{ + pathStr:=strconv.Itoa((*path)[0]) + for i:=1;i"+strconv.Itoa((*path)[i]) + } + *result=append(*result,pathStr) + return + } + //左右 + if root.Left!=nil{ + traversal(root.Left,result,path) + *path=(*path)[:len(*path)-1]//回溯到上一个节点（因为traversal会加下一个节点值到path中） + } + if root.Right!=nil{ + traversal(root.Right,result,path) + *path=(*path)[:len(*path)-1]//回溯 + } +} +``` + + From 14542ac3404b82ad492ea50cde7f56a6051185dd Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 12 Jun 2021 14:25:27 +0800 Subject: [PATCH 068/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=EF=BC=9A=E4=BB=A5=E4=B8=BA=E4=BD=BF=E7=94=A8=E4=BA=86?= =?UTF-8?q?=E9=80=92=E5=BD=92=EF=BC=8C=E5=85=B6=E5=AE=9E=E8=BF=98=E9=9A=90?= =?UTF-8?q?=E8=97=8F=E7=9D=80=E5=9B=9E=E6=BA=AF=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 二叉树：以为使用了递归，其实还隐藏着回溯 go版本 --- problems/二叉树中递归带着回溯.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/二叉树中递归带着回溯.md b/problems/二叉树中递归带着回溯.md index 8014d6e1..372dc40c 100644 --- a/problems/二叉树中递归带着回溯.md +++ b/problems/二叉树中递归带着回溯.md @@ -336,6 +336,7 @@ class Solution: ``` Go： + 100.相同的树 ```go /** @@ -351,7 +352,6 @@ func isSameTree(p *TreeNode, q *TreeNode) bool { case p == nil && q == nil: return true case p == nil || q == nil: - fmt.Println(p,q) fallthrough case p.Val != q.Val: return false From 8e44f0a11b1f31c03b8cbcc1c3cda4d37042d1ff Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 12 Jun 2021 19:56:09 +0800 Subject: [PATCH 069/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20404.=E5=B7=A6?= =?UTF-8?q?=E5=8F=B6=E5=AD=90=E4=B9=8B=E5=92=8C=20Javascript=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 404.左叶子之和 Javascript版本 --- problems/0404.左叶子之和.md | 65 ++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md index e5daa9db..e6a6682b 100644 --- a/problems/0404.左叶子之和.md +++ b/problems/0404.左叶子之和.md @@ -226,6 +226,71 @@ class Solution: ``` Go： +> 递归法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func sumOfLeftLeaves(root *TreeNode) int { + var res int + findLeft(root,&res) + return res +} +func findLeft(root *TreeNode,res *int){ + //左节点 + if root.Left!=nil&&root.Left.Left==nil&&root.Left.Right==nil{ + *res=*res+root.Left.Val + } + if root.Left!=nil{ + findLeft(root.Left,res) + } + if root.Right!=nil{ + findLeft(root.Right,res) + } +} +``` + +> 迭代法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func sumOfLeftLeaves(root *TreeNode) int { + var res int + queue:=list.New() + queue.PushBack(root) + for queue.Len()>0{ + length:=queue.Len() + for i:=0;i Date: Sat, 12 Jun 2021 21:55:15 +0800 Subject: [PATCH 070/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20513.=E6=89=BE?= =?UTF-8?q?=E6=A0=91=E5=B7=A6=E4=B8=8B=E8=A7=92=E7=9A=84=E5=80=BC=20go?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 513.找树左下角的值 go版本 --- problems/0513.找树左下角的值.md | 74 ++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/problems/0513.找树左下角的值.md b/problems/0513.找树左下角的值.md index 97464e3d..e252ccd3 100644 --- a/problems/0513.找树左下角的值.md +++ b/problems/0513.找树左下角的值.md @@ -298,6 +298,80 @@ class Solution: ``` Go： +> 递归法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + var maxDeep int // 全局变量 深度 + var value int //全局变量 最终值 +func findBottomLeftValue(root *TreeNode) int { + if root.Left==nil&&root.Right==nil{//需要提前判断一下（不要这个if的话提交结果会出错，但执行代码不会。防止这种情况出现，故先判断是否只有一个节点） + return root.Val + } + findLeftValue (root,maxDeep) + return value +} +func findLeftValue (root *TreeNode,deep int){ + //最左边的值在左边 + if root.Left==nil&&root.Right==nil{ + if deep>maxDeep{ + value=root.Val + maxDeep=deep + } + } + //递归 + if root.Left!=nil{ + deep++ + findLeftValue(root.Left,deep) + deep--//回溯 + } + if root.Right!=nil{ + deep++ + findLeftValue(root.Right,deep) + deep--//回溯 + } +} +``` + +> 迭代法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func findBottomLeftValue(root *TreeNode) int { + queue:=list.New() + var gradation int + queue.PushBack(root) + for queue.Len()>0{ + length:=queue.Len() + for i:=0;i Date: Sat, 12 Jun 2021 21:57:47 +0800 Subject: [PATCH 071/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20404.=E5=B7=A6?= =?UTF-8?q?=E5=8F=B6=E5=AD=90=E4=B9=8B=E5=92=8C=20GO=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 404.左叶子之和 GO版本 --- problems/0404.左叶子之和.md | 1 + 1 file changed, 1 insertion(+) diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md index e6a6682b..aa758367 100644 --- a/problems/0404.左叶子之和.md +++ b/problems/0404.左叶子之和.md @@ -340,6 +340,7 @@ var sumOfLeftLeaves = function(root) { + ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频：[代码随想录](https://space.bilibili.com/525438321) From 93b8dda7ca2567d11198c2dd04df48864f39d645 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 12 Jun 2021 23:34:37 +0800 Subject: [PATCH 072/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200112.=E8=B7=AF?= =?UTF-8?q?=E5=BE=84=E6=80=BB=E5=92=8C=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0112.路径总和.md | 86 +++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) diff --git a/problems/0112.路径总和.md b/problems/0112.路径总和.md index d810a046..54f79d1d 100644 --- a/problems/0112.路径总和.md +++ b/problems/0112.路径总和.md @@ -486,6 +486,92 @@ class Solution: Go： +> 112. 路径总和 + +```go +//递归法 +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func hasPathSum(root *TreeNode, targetSum int) bool { + var flage bool //找没找到的标志 + if root==nil{ + return flage + } + pathSum(root,0,targetSum,&flage) + return flage +} +func pathSum(root *TreeNode, sum int,targetSum int,flage *bool){ + sum+=root.Val + if root.Left==nil&&root.Right==nil&&sum==targetSum{ + *flage=true + return + } + if root.Left!=nil&&!(*flage){//左节点不为空且还没找到 + pathSum(root.Left,sum,targetSum,flage) + } + if root.Right!=nil&&!(*flage){//右节点不为空且没找到 + pathSum(root.Right,sum,targetSum,flage) + } +} +``` + + + +> 113 递归法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func pathSum(root *TreeNode, targetSum int) [][]int { + var result [][]int//最终结果 + if root==nil{ + return result + } + var sumNodes []int//经过路径的节点集合 + hasPathSum(root,&sumNodes,targetSum,&result) + return result +} +func hasPathSum(root *TreeNode,sumNodes *[]int,targetSum int,result *[][]int){ + *sumNodes=append(*sumNodes,root.Val) + if root.Left==nil&&root.Right==nil{//叶子节点 + fmt.Println(*sumNodes) + var sum int + var number int + for k,v:=range *sumNodes{//求该路径节点的和 + sum+=v + number=k + } + tempNodes:=make([]int,number+1)//新的nodes接受指针里的值，防止最终指针里的值发生变动，导致最后的结果都是最后一个sumNodes的值 + for k,v:=range *sumNodes{ + tempNodes[k]=v + } + if sum==targetSum{ + *result=append(*result,tempNodes) + } + } + if root.Left!=nil{ + hasPathSum(root.Left,sumNodes,targetSum,result) + *sumNodes=(*sumNodes)[:len(*sumNodes)-1]//回溯 + } + if root.Right!=nil{ + hasPathSum(root.Right,sumNodes,targetSum,result) + *sumNodes=(*sumNodes)[:len(*sumNodes)-1]//回溯 + } +} +``` + JavaScript： 0112.路径总和 From e445b35d3691edf9ec0ab9fe30aaa6357b3c518a Mon Sep 17 00:00:00 2001 From: NevS <1173325467@qq.com> Date: Sun, 13 Jun 2021 01:55:37 +0800 Subject: [PATCH 073/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200239.=E6=BB=91?= =?UTF-8?q?=E5=8A=A8=E7=AA=97=E5=8F=A3=E6=9C=80=E5=A4=A7=E5=80=BC=20go?= =?UTF-8?q?=E7=89=88=20=EF=BC=88=E5=A2=9E=E5=8A=A0=E5=B0=81=E8=A3=85?= =?UTF-8?q?=E5=8D=95=E8=B0=83=E9=98=9F=E5=88=97=E8=A7=A3=E9=A2=98=E7=9A=84?= =?UTF-8?q?=E6=96=B9=E5=BC=8F=EF=BC=89?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 增加封装单调队列解题的方式 --- problems/0239.滑动窗口最大值.md | 60 ++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) diff --git a/problems/0239.滑动窗口最大值.md b/problems/0239.滑动窗口最大值.md index 47383a47..d108335b 100644 --- a/problems/0239.滑动窗口最大值.md +++ b/problems/0239.滑动窗口最大值.md @@ -332,6 +332,66 @@ func maxSlidingWindow(nums []int, k int) []int { ``` +```go +// 封装单调队列的方式解题 +type MyQueue struct { + queue []int +} + +func NewMyQueue() *MyQueue { + return &MyQueue{ + queue: make([]int, 0), + } +} + +func (m *MyQueue) Front() int { + return m.queue[0] +} + +func (m *MyQueue) Back() int { + return m.queue[len(m.queue)-1] +} + +func (m *MyQueue) Empty() bool { + return len(m.queue) == 0 +} + +func (m *MyQueue) Push(val int) { + for !m.Empty() && val > m.Back() { + m.queue = m.queue[:len(m.queue)-1] + } + m.queue = append(m.queue, val) +} + +func (m *MyQueue) Pop(val int) { + if !m.Empty() && val == m.Front() { + m.queue = m.queue[1:] + } +} + +func maxSlidingWindow(nums []int, k int) []int { + queue := NewMyQueue() + length := len(nums) + res := make([]int, 0) + // 先将前k个元素放入队列 + for i := 0; i < k; i++ { + queue.Push(nums[i]) + } + // 记录前k个元素的最大值 + res = append(res, queue.Front()) + + for i := k; i < length; i++ { + // 滑动窗口移除最前面的元素 + queue.Pop(nums[i-k]) + // 滑动窗口添加最后面的元素 + queue.Push(nums[i]) + // 记录最大值 + res = append(res, queue.Front()) + } + return res +} +``` + Javascript: ```javascript var maxSlidingWindow = function (nums, k) { From f5b8f8faeb8aa5965e534ba41ae8a2ea378d20b2 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Sat, 12 Jun 2021 13:57:42 -0400 Subject: [PATCH 074/122] =?UTF-8?q?=E6=9B=B4=E6=96=B00343.=E6=95=B4?= =?UTF-8?q?=E6=95=B0=E6=8B=86=E5=88=86.md=20python3=E4=BB=A3=E7=A0=81=20-?= =?UTF-8?q?=20=E5=B0=8F=E6=94=B9=E5=8A=A8?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 根据讲解, dp[0], dp[1]不应该初始化. 如果 是for j in range(1, i): 递归方程就会需要dp[1]. 虽然也可以AC, 但是不合逻辑. --- problems/0343.整数拆分.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0343.整数拆分.md b/problems/0343.整数拆分.md index fefaa293..cf60575f 100644 --- a/problems/0343.整数拆分.md +++ b/problems/0343.整数拆分.md @@ -218,7 +218,7 @@ class Solution: # 假设对正整数 i 拆分出的第一个正整数是 j（1 <= j < i），则有以下两种方案： # 1) 将 i 拆分成 j 和 i−j 的和，且 i−j 不再拆分成多个正整数，此时的乘积是 j * (i-j) # 2) 将 i 拆分成 j 和 i−j 的和，且 i−j 继续拆分成多个正整数，此时的乘积是 j * dp[i-j] - for j in range(1, i): + for j in range(1, i - 1): dp[i] = max(dp[i], max(j * (i - j), j * dp[i - j])) return dp[n] ``` From 6673c56916ac17ed48b7a30bffe3d8912773a0b1 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Sat, 12 Jun 2021 14:12:08 -0400 Subject: [PATCH 075/122] =?UTF-8?q?Update=20=E8=83=8C=E5=8C=85=E7=90=86?= =?UTF-8?q?=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-1.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 修改indention. --- problems/背包理论基础01背包-1.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index 852c489b..36544256 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -268,7 +268,7 @@ int main() { Java： ```java - public static void main(String[] args) { + public static void main(String[] args) { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagSize = 4; From 6a42937927f1e9c9c4925fa53332ddf4fe275d24 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Sat, 12 Jun 2021 14:29:59 -0400 Subject: [PATCH 076/122] =?UTF-8?q?Update=20=E8=83=8C=E5=8C=85=E7=90=86?= =?UTF-8?q?=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md=20Python?= =?UTF-8?q?=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 增加python部分代码. 测试结果: ``` [[0, 15, 15, 15, 15], [0, 15, 15, 20, 35], [0, 15, 15, 20, 35]] ``` 与题解一致. --- problems/背包理论基础01背包-1.md | 35 ++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index 36544256..1269d9c1 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -307,6 +307,41 @@ Java： Python： +```python +def test_2_wei_bag_problem1(bag_size, weight, value) -> int: + rows, cols = len(weight), bag_size + 1 + dp = [[0 for _ in range(cols)] for _ in range(rows)] + res = 0 + + # 初始化dp数组. + for i in range(rows): + dp[i][0] = 0 + first_item_weight, first_item_value = weight[0], value[0] + for j in range(1, cols): + if first_item_weight <= j: + dp[0][j] = first_item_value + + # 更新dp数组: 先遍历物品, 再遍历背包. + for i in range(1, len(weight)): + cur_weight, cur_val = weight[i], value[i] + for j in range(1, cols): + if cur_weight > j: # 说明背包装不下当前物品. + dp[i][j] = dp[i - 1][j] # 所以不装当前物品. + else: + # 定义dp数组: dp[i][j] 前i个物品里，放进容量为j的背包，价值总和最大是多少。 + dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - cur_weight]+ cur_val) + if dp[i][j] > res: + res = dp[i][j] + + print(dp) + + +if __name__ == "__main__": + bag_size = 4 + weight = [1, 3, 4] + value = [15, 20, 30] + test_2_wei_bag_problem1(bag_size, weight, value) +``` Go： From be2804f8740e5027354265d722d77e9e89e7fd0d Mon Sep 17 00:00:00 2001 From: Kelvin Date: Sat, 12 Jun 2021 14:30:30 -0400 Subject: [PATCH 077/122] =?UTF-8?q?Revert=20"Update=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-1.md"?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This reverts commit 6673c56916ac17ed48b7a30bffe3d8912773a0b1. --- problems/背包理论基础01背包-1.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index 1269d9c1..f6646202 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -268,7 +268,7 @@ int main() { Java： ```java - public static void main(String[] args) { + public static void main(String[] args) { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagSize = 4; From 737b7c38e86a1365b99f4bcc4ef354c04dd44955 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Sat, 12 Jun 2021 14:32:08 -0400 Subject: [PATCH 078/122] =?UTF-8?q?=E6=9B=B4=E6=94=B9=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20Java=E6=A0=BC=E5=BC=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 原版在github上显示不正确. --- problems/背包理论基础01背包-1.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-1.md b/problems/背包理论基础01背包-1.md index f6646202..1269d9c1 100644 --- a/problems/背包理论基础01背包-1.md +++ b/problems/背包理论基础01背包-1.md @@ -268,7 +268,7 @@ int main() { Java： ```java - public static void main(String[] args) { + public static void main(String[] args) { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagSize = 4; From 3e506df04426ca8937f09f7a8e9ca9955d0d1c7e Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Sun, 13 Jun 2021 10:56:21 +0800 Subject: [PATCH 079/122] =?UTF-8?q?update=E6=9C=89=E6=95=88=E7=9A=84?= =?UTF-8?q?=E5=AD=97=E6=AF=8D=E5=BC=82=E4=BD=8D=E8=AF=8D=EF=BC=8Cpython?= =?UTF-8?q?=E4=BB=A3=E7=A0=81=E6=B7=BB=E5=8A=A0=E4=BA=86=E6=9B=B4pythonic?= =?UTF-8?q?=E7=9A=84=E5=86=99=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0242.有效的字母异位词.md | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/problems/0242.有效的字母异位词.md b/problems/0242.有效的字母异位词.md index ba942f70..c3e73730 100644 --- a/problems/0242.有效的字母异位词.md +++ b/problems/0242.有效的字母异位词.md @@ -130,7 +130,27 @@ class Solution: return True ``` +Python写法二： + +```python +class Solution: + def isAnagram(self, s: str, t: str) -> bool: + from collections import defaultdict + + s_dict=defaultdict(int) + t_dict=defaultdict(int) + + for x in s: + s_dict[x]+=1 + + for x in t: + t_dict[x]+=1 + + return s_dict==t_dict +``` + Go： + ```go func isAnagram(s string, t string) bool { if len(s)!=len(t){ From 0d3b8de51227c0c55ace89aa249e0a25377a62be Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Sun, 13 Jun 2021 10:58:05 +0800 Subject: [PATCH 080/122] =?UTF-8?q?=E6=9B=B4=E6=96=B0=E4=BB=A3=E7=A0=81?= =?UTF-8?q?=E8=A7=84=E8=8C=83?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0242.有效的字母异位词.md | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/problems/0242.有效的字母异位词.md b/problems/0242.有效的字母异位词.md index c3e73730..1956253a 100644 --- a/problems/0242.有效的字母异位词.md +++ b/problems/0242.有效的字母异位词.md @@ -137,16 +137,16 @@ class Solution: def isAnagram(self, s: str, t: str) -> bool: from collections import defaultdict - s_dict=defaultdict(int) - t_dict=defaultdict(int) + s_dict = defaultdict(int) + t_dict = defaultdict(int) for x in s: - s_dict[x]+=1 + s_dict[x] += 1 for x in t: - t_dict[x]+=1 + t_dict[x] += 1 - return s_dict==t_dict + return s_dict == t_dict ``` Go： From 4993e9ff6bfab26473eeb9b99f07ae544f0afca3 Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Sun, 13 Jun 2021 11:14:21 +0800 Subject: [PATCH 081/122] =?UTF-8?q?=E6=9C=89=E6=95=88=E7=9A=84=E5=AD=97?= =?UTF-8?q?=E6=AF=8D=E5=BC=82=E4=BD=8D=E8=AF=8D=E6=B7=BB=E5=8A=A0=E4=B8=80?= =?UTF-8?q?=E4=BA=9B=E8=AF=B4=E6=98=8E?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0242.有效的字母异位词.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0242.有效的字母异位词.md b/problems/0242.有效的字母异位词.md index 1956253a..93bba44c 100644 --- a/problems/0242.有效的字母异位词.md +++ b/problems/0242.有效的字母异位词.md @@ -130,7 +130,7 @@ class Solution: return True ``` -Python写法二： +Python写法二（没有使用数组作为哈希表，只是介绍defaultdict这样一种解题思路）： ```python class Solution: From 2c03dfc3f33085a9e5440d7f26b2dc84f5514d47 Mon Sep 17 00:00:00 2001 From: KailokFung Date: Sun, 13 Jun 2021 13:29:59 +0800 Subject: [PATCH 082/122] =?UTF-8?q?feat(0707):=20=E6=96=B0=E5=A2=9Ejava=20?= =?UTF-8?q?=E5=8F=8C=E9=93=BE=E8=A1=A8=20=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0707.设计链表.md | 101 ++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) diff --git a/problems/0707.设计链表.md b/problems/0707.设计链表.md index 2fa1af29..7d5fde1f 100644 --- a/problems/0707.设计链表.md +++ b/problems/0707.设计链表.md @@ -158,6 +158,7 @@ private: Java： ```Java +//单链表 class ListNode { int val; ListNode next; @@ -236,6 +237,106 @@ class MyLinkedList { pred.next = pred.next.next; } } + +//双链表 +class MyLinkedList { + class ListNode { + int val; + ListNode next,prev; + ListNode(int x) {val = x;} + } + + int size; + ListNode head,tail;//Sentinel node + + /** Initialize your data structure here. */ + public MyLinkedList() { + size = 0; + head = new ListNode(0); + tail = new ListNode(0); + head.next = tail; + tail.prev = head; + } + + /** Get the value of the index-th node in the linked list. If the index is invalid, return -1. */ + public int get(int index) { + if(index < 0 || index >= size){return -1;} + ListNode cur = head; + + // 通过判断 index < (size - 1) / 2 来决定是从头结点还是尾节点遍历，提高效率 + if(index < (size - 1) / 2){ + for(int i = 0; i <= index; i++){ + cur = cur.next; + } + }else{ + cur = tail; + for(int i = 0; i <= size - index - 1; i++){ + cur = cur.prev; + } + } + return cur.val; + } + + /** Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list. */ + public void addAtHead(int val) { + ListNode cur = head; + ListNode newNode = new ListNode(val); + newNode.next = cur.next; + cur.next.prev = newNode; + cur.next = newNode; + newNode.prev = cur; + size++; + } + + /** Append a node of value val to the last element of the linked list. */ + public void addAtTail(int val) { + ListNode cur = tail; + ListNode newNode = new ListNode(val); + newNode.next = tail; + newNode.prev = cur.prev; + cur.prev.next = newNode; + cur.prev = newNode; + size++; + } + + /** Add a node of value val before the index-th node in the linked list. If index equals to the length of linked list, the node will be appended to the end of linked list. If index is greater than the length, the node will not be inserted. */ + public void addAtIndex(int index, int val) { + if(index > size){return;} + if(index < 0){index = 0;} + ListNode cur = head; + for(int i = 0; i < index; i++){ + cur = cur.next; + } + ListNode newNode = new ListNode(val); + newNode.next = cur.next; + cur.next.prev = newNode; + newNode.prev = cur; + cur.next = newNode; + size++; + } + + /** Delete the index-th node in the linked list, if the index is valid. */ + public void deleteAtIndex(int index) { + if(index >= size || index < 0){return;} + ListNode cur = head; + for(int i = 0; i < index; i++){ + cur = cur.next; + } + cur.next.next.prev = cur; + cur.next = cur.next.next; + size--; + } +} + +/** + * Your MyLinkedList object will be instantiated and called as such: + * MyLinkedList obj = new MyLinkedList(); + * int param_1 = obj.get(index); + * obj.addAtHead(val); + * obj.addAtTail(val); + * obj.addAtIndex(index,val); + * obj.deleteAtIndex(index); + */ ``` Python： From f16d590a7f2015fcee1854fb906a220091c58135 Mon Sep 17 00:00:00 2001 From: Ysc Date: Sun, 13 Jun 2021 18:40:02 +0900 Subject: [PATCH 083/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20977.=E6=9C=89?= =?UTF-8?q?=E5=BA=8F=E6=95=B0=E7=BB=84=E7=9A=84=E5=B9=B3=E6=96=B9=20Javasc?= =?UTF-8?q?ript=20=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0977.有序数组的平方.md | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/problems/0977.有序数组的平方.md b/problems/0977.有序数组的平方.md index d2e1f950..0f9007d7 100644 --- a/problems/0977.有序数组的平方.md +++ b/problems/0977.有序数组的平方.md @@ -198,6 +198,31 @@ impl Solution { } } ``` +Javascript： +```Javascript +/** + * @desc two pointers solution + * @link https://leetcode-cn.com/problems/squares-of-a-sorted-array/ + * @param nums Array e.g. [-4,-1,0,3,10] + * @return {array} e.g. [0,1,9,16,100] + */ +const sortedSquares = function (nums) { + let res = [] + for (let i = 0, j = nums.length - 1; i <= j;) { + const left = Math.abs(nums[i]) + const right = Math.abs(nums[j]) + if (right > left) { + // push element to the front of the array + res.unshift(right * right) + j-- + } else { + res.unshift(left * left) + i++ + } + } + return res + } +``` ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From 56d9af976a6df55808ebf8e834ed6cac7bfc38e1 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 13 Jun 2021 20:30:46 +0800 Subject: [PATCH 084/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200106.=E4=BB=8E?= =?UTF-8?q?=E4=B8=AD=E5=BA=8F=E4=B8=8E=E5=90=8E=E5=BA=8F=E9=81=8D=E5=8E=86?= =?UTF-8?q?=E5=BA=8F=E5=88=97=E6=9E=84=E9=80=A0=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0106.从中序与后序遍历序列构造二叉树 go版本 --- ...序与后序遍历序列构造二叉树.md | 64 +++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/problems/0106.从中序与后序遍历序列构造二叉树.md b/problems/0106.从中序与后序遍历序列构造二叉树.md index ba2d46a1..600a38e0 100644 --- a/problems/0106.从中序与后序遍历序列构造二叉树.md +++ b/problems/0106.从中序与后序遍历序列构造二叉树.md @@ -693,6 +693,70 @@ class Solution: return root ``` Go： +> 106 从中序与后序遍历序列构造二叉树 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func buildTree(inorder []int, postorder []int) *TreeNode { + if len(inorder)<1||len(postorder)<1{return nil} + //先找到根节点（后续遍历的最后一个就是根节点） + nodeValue:=postorder[len(postorder)-1] + //从中序遍历中找到一分为二的点，左边为左子树，右边为右子树 + left:=findRootIndex(inorder,nodeValue) + //构造root + root:=&TreeNode{Val: nodeValue, + Left: buildTree(inorder[:left],postorder[:left]),//将后续遍历一分为二，左边为左子树，右边为右子树 + Right: buildTree(inorder[left+1:],postorder[left:len(postorder)-1])} + return root +} +func findRootIndex(inorder []int,target int) (index int){ + for i:=0;i 105 从前序与中序遍历序列构造二叉树 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func buildTree(preorder []int, inorder []int) *TreeNode { + if len(preorder)<1||len(inorder)<1{return nil} + left:=findRootIndex(preorder[0],inorder) + root:=&TreeNode{ + Val: preorder[0], + Left: buildTree(preorder[1:left+1],inorder[:left]), + Right: buildTree(preorder[left+1:],inorder[left+1:])} + return root +} +func findRootIndex(target int,inorder []int) int{ + for i:=0;i Date: Sun, 13 Jun 2021 20:48:38 +0800 Subject: [PATCH 085/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200654.=E6=9C=80?= =?UTF-8?q?=E5=A4=A7=E4=BA=8C=E5=8F=89=E6=A0=91=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0654.最大二叉树 go版本 --- problems/0654.最大二叉树.md | 33 ++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/problems/0654.最大二叉树.md b/problems/0654.最大二叉树.md index ea8c15cd..f0d3e594 100644 --- a/problems/0654.最大二叉树.md +++ b/problems/0654.最大二叉树.md @@ -278,6 +278,39 @@ class Solution: Go： +> 654. 最大二叉树 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func constructMaximumBinaryTree(nums []int) *TreeNode { + if len(nums)<1{return nil} + //首选找到最大值 + index:=findMax(nums) + //其次构造二叉树 + root:=&TreeNode{ + Val: nums[index], + Left:constructMaximumBinaryTree(nums[:index]),//左半边 + Right:constructMaximumBinaryTree(nums[index+1:]),//右半边 + } + return root +} +func findMax(nums []int) (index int){ + for i:=0;inums[index]{ + index=i + } + } + return +} +``` + From 0e267fda96857c884f8cf920c20f00f4f5d1e6a3 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 13 Jun 2021 20:56:40 +0800 Subject: [PATCH 086/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200739.=E6=AF=8F?= =?UTF-8?q?=E6=97=A5=E6=B8=A9=E5=BA=A6=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0739.每日温度 go版本 --- problems/0739.每日温度.md | 46 +++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/problems/0739.每日温度.md b/problems/0739.每日温度.md index 1f91e42a..eeea6ead 100644 --- a/problems/0739.每日温度.md +++ b/problems/0739.每日温度.md @@ -214,6 +214,52 @@ Python： Go： +> 暴力法 + +```go +func dailyTemperatures(temperatures []int) []int { + length:=len(temperatures) + res:=make([]int,length) + for i:=0;i=temperatures[j]{//大于等于 + j++ + } + if j 单调栈法 + +```go +func dailyTemperatures(temperatures []int) []int { + length:=len(temperatures) + res:=make([]int,length) + stack:=[]int{} + for i:=0;i0&&temperatures[i]>temperatures[stack[len(stack)-1]]{ + res[stack[len(stack)-1]]=i-stack[len(stack)-1]//存放结果集 + stack=stack[:len(stack)-1]//删除stack[len(stack)-1]的元素 + } + //如果栈顶元素大于等于新来的元素，则加入到栈中。当栈内元素个数为0时，直接入栈 + if len(stack)==0||temperatures[i]<=temperatures[stack[len(stack)-1]]{ + stack = append(stack, i) + } + } + return res +} +``` From 01f87cc50566c9a171f6c828d1eb2b9f5828f646 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 13 Jun 2021 21:48:05 +0800 Subject: [PATCH 087/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200617.=E5=90=88?= =?UTF-8?q?=E5=B9=B6=E4=BA=8C=E5=8F=89=E6=A0=91=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0617.合并二叉树 go版本 --- problems/0617.合并二叉树.md | 37 ++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/problems/0617.合并二叉树.md b/problems/0617.合并二叉树.md index d65275f0..be6bb425 100644 --- a/problems/0617.合并二叉树.md +++ b/problems/0617.合并二叉树.md @@ -332,6 +332,43 @@ class Solution: Go： +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + //前序遍历（递归遍历，跟105 106差不多的思路） +func mergeTrees(t1 *TreeNode, t2 *TreeNode) *TreeNode { + var value int + var nullNode *TreeNode//空node，便于遍历 + nullNode=&TreeNode{ + Val:0, + Left:nil, + Right:nil} + switch { + case t1==nil&&t2==nil: return nil//终止条件 + default : //如果其中一个节点为空，则将该节点置为nullNode，方便下次遍历 + if t1==nil{ + value=t2.Val + t1=nullNode + }else if t2==nil{ + value=t1.Val + t2=nullNode + }else { + value=t1.Val+t2.Val + } + } + root:=&TreeNode{//构造新的二叉树 + Val: value, + Left: mergeTrees(t1.Left,t2.Left), + Right: mergeTrees(t1.Right,t2.Right)} + return root +} +``` From ac1e326cbf15017d2a98d53620016f3bb6069421 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 13 Jun 2021 22:17:57 +0800 Subject: [PATCH 088/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200700.=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=E4=B8=AD=E7=9A=84=E6=90=9C?= =?UTF-8?q?=E7=B4=A2=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0700.二叉搜索树中的搜索 go版本 --- problems/0700.二叉搜索树中的搜索.md | 50 ++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/problems/0700.二叉搜索树中的搜索.md b/problems/0700.二叉搜索树中的搜索.md index 25a06617..16b21f26 100644 --- a/problems/0700.二叉搜索树中的搜索.md +++ b/problems/0700.二叉搜索树中的搜索.md @@ -241,6 +241,56 @@ class Solution: Go： +> 递归法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + //递归法 +func searchBST(root *TreeNode, val int) *TreeNode { + if root==nil||root.Val==val{ + return root + } + if root.Val>val{ + return searchBST(root.Left,val) + } + return searchBST(root.Right,val) +} +``` + +> 迭代法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + //迭代法 +func searchBST(root *TreeNode, val int) *TreeNode { + for root!=nil{ + if root.Val>val{ + root=root.Left + }else if root.Val Date: Mon, 14 Jun 2021 12:58:03 +0800 Subject: [PATCH 089/122] =?UTF-8?q?Update=20=E8=83=8C=E5=8C=85=E9=97=AE?= =?UTF-8?q?=E9=A2=98=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=80=E5=A4=9A=E9=87=8D?= =?UTF-8?q?=E8=83=8C=E5=8C=85.md=20=E6=B7=BB=E5=8A=A0=20python3=20?= =?UTF-8?q?=E7=89=88=E6=9C=AC=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../背包问题理论基础多重背包.md | 49 ++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) diff --git a/problems/背包问题理论基础多重背包.md b/problems/背包问题理论基础多重背包.md index 26890a2b..e14575d4 100644 --- a/problems/背包问题理论基础多重背包.md +++ b/problems/背包问题理论基础多重背包.md @@ -147,9 +147,56 @@ int main() { Java： - Python： +```python +def test_multi_pack1(): + '''版本一：改变物品数量为01背包格式''' + weight = [1, 3, 4] + value = [15, 20, 30] + nums = [2, 3, 2] + bag_weight = 10 + for i in range(len(nums)): + # 将物品展开数量为1 + while nums[i] > 1: + weight.append(weight[i]) + value.append(value[i]) + nums[i] -= 1 + + dp = [0]*(bag_weight + 1) + # 遍历物品 + for i in range(len(weight)): + # 遍历背包 + for j in range(bag_weight, weight[i] - 1, -1): + dp[j] = max(dp[j], dp[j - weight[i]] + value[i]) + + print(" ".join(map(str, dp))) + +def test_multi_pack2(): + '''版本：改变遍历个数''' + weight = [1, 3, 4] + value = [15, 20, 30] + nums = [2, 3, 2] + bag_weight = 10 + + dp = [0]*(bag_weight + 1) + for i in range(len(weight)): + for j in range(bag_weight, weight[i] - 1, -1): + # 以上是01背包，加上遍历个数 + for k in range(1, nums[i] + 1): + if j - k*weight[i] >= 0: + dp[j] = max(dp[j], dp[j - k*weight[i]] + k*value[i]) + + print(" ".join(map(str, dp))) + + +if __name__ == '__main__': + test_multi_pack1() + test_multi_pack2() +``` + + + Go： From a47eddd56feb76cd95eae8d02fee30b5740c9ade Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Mon, 14 Jun 2021 21:56:40 +0800 Subject: [PATCH 090/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200530.=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=E7=9A=84=E6=9C=80=E5=B0=8F?= =?UTF-8?q?=E7=BB=9D=E5=AF=B9=E5=B7=AE=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0530.二叉搜索树的最小绝对差 go版本 --- .../0530.二叉搜索树的最小绝对差.md | 31 ++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/problems/0530.二叉搜索树的最小绝对差.md b/problems/0530.二叉搜索树的最小绝对差.md index 03c48d9c..0bbc4908 100644 --- a/problems/0530.二叉搜索树的最小绝对差.md +++ b/problems/0530.二叉搜索树的最小绝对差.md @@ -224,8 +224,37 @@ class Solution: return r ``` Go： +> 中序遍历，然后计算最小差值 - +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func getMinimumDifference(root *TreeNode) int { + var res []int + findMIn(root,&res) + min:=1000000//一个比较大的值 + for i:=1;i Date: Mon, 14 Jun 2021 23:10:10 +0800 Subject: [PATCH 091/122] =?UTF-8?q?=E4=BF=AE=E5=A4=8D:=E2=80=9C=E6=93=8D?= =?UTF-8?q?=E4=BD=9C=E4=B8=80=E2=80=9D=E4=B8=AD`i-1`=E6=94=B9=E6=AD=A3?= =?UTF-8?q?=E4=B8=BA`j-1`,=20=20=E5=B9=B6=E6=B7=BB=E5=8A=A0=E4=BA=86?= =?UTF-8?q?=E5=88=A0=E9=99=A4=E5=85=83=E7=B4=A0=E7=9A=84=E8=A7=A3=E9=87=8A?= =?UTF-8?q?=EF=BC=8C=E5=90=8C=E6=97=B6=E4=BF=AE=E6=94=B9=E4=BA=86=E6=96=87?= =?UTF-8?q?=E6=A1=A3=E9=83=A8=E5=88=86=E6=A0=B7=E5=BC=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0072.编辑距离.md | 123 ++++++++++++++++++++-------------- 1 file changed, 74 insertions(+), 49 deletions(-) diff --git a/problems/0072.编辑距离.md b/problems/0072.编辑距离.md index 2044ac25..26f080fe 100644 --- a/problems/0072.编辑距离.md +++ b/problems/0072.编辑距离.md @@ -8,7 +8,7 @@ ## 72. 编辑距离 -https://leetcode-cn.com/problems/edit-distance/ +https://leetcode-cn.com/problems/edit-distance/ 给你两个单词 word1 和 word2，请你计算出将 word1 转换成 word2 所使用的最少操作数 。 @@ -18,23 +18,23 @@ https://leetcode-cn.com/problems/edit-distance/ * 删除一个字符 * 替换一个字符 -示例 1： -输入：word1 = "horse", word2 = "ros" -输出：3 -解释： -horse -> rorse (将 'h' 替换为 'r') -rorse -> rose (删除 'r') -rose -> ros (删除 'e') +示例 1： +输入：word1 = "horse", word2 = "ros" +输出：3 +解释： +horse -> rorse (将 'h' 替换为 'r') +rorse -> rose (删除 'r') +rose -> ros (删除 'e') -示例 2： -输入：word1 = "intention", word2 = "execution" -输出：5 -解释： -intention -> inention (删除 't') -inention -> enention (将 'i' 替换为 'e') -enention -> exention (将 'n' 替换为 'x') -exention -> exection (将 'n' 替换为 'c') -exection -> execution (插入 'u') +示例 2： +输入：word1 = "intention", word2 = "execution" +输出：5 +解释： +intention -> inention (删除 't') +inention -> enention (将 'i' 替换为 'e') +enention -> exention (将 'n' 替换为 'x') +exention -> exection (将 'n' 替换为 'c') +exection -> execution (插入 'u')   提示： @@ -51,7 +51,9 @@ exection -> execution (插入 'u') 接下来我依然使用动规五部曲，对本题做一个详细的分析： -1. 确定dp数组（dp table）以及下标的含义 +----------------------- + +### 1. 确定dp数组（dp table）以及下标的含义 **dp[i][j] 表示以下标i-1为结尾的字符串word1，和以下标j-1为结尾的字符串word2，最近编辑距离为dp[i][j]**。 @@ -59,49 +61,65 @@ exection -> execution (插入 'u') 用i来表示也可以！ 但我统一以下标i-1为结尾的字符串，在下面的递归公式中会容易理解一点。 -2. 确定递推公式 +----------------------- + +### 2. 确定递推公式 在确定递推公式的时候，首先要考虑清楚编辑的几种操作，整理如下： -* if (word1[i - 1] == word2[j - 1]) - * 不操作 -* if (word1[i - 1] != word2[j - 1]) - * 增 - * 删 - * 换 +``` +if (word1[i - 1] == word2[j - 1]) + 不操作 +if (word1[i - 1] != word2[j - 1]) + 增 + 删 + 换 +``` -也就是如上四种情况。 +也就是如上4种情况。 -if (word1[i - 1] == word2[j - 1]) 那么说明不用任何编辑，dp[i][j] 就应该是 dp[i - 1][j - 1]，即dp[i][j] = dp[i - 1][j - 1]; +`if (word1[i - 1] == word2[j - 1])` 那么说明不用任何编辑，`dp[i][j]` 就应该是 `dp[i - 1][j - 1]`，即`dp[i][j] = dp[i - 1][j - 1];` -此时可能有同学有点不明白，为啥要即dp[i][j] = dp[i - 1][j - 1]呢？ +此时可能有同学有点不明白，为啥要即`dp[i][j] = dp[i - 1][j - 1]`呢？ -那么就在回顾上面讲过的dp[i][j]的定义，word1[i - 1] 与 word2[j - 1]相等了，那么就不用编辑了，以下标i-2为结尾的字符串word1和以下标j-2为结尾的字符串word2的最近编辑距离dp[i - 1][j - 1] 就是 dp[i][j]了。 +那么就在回顾上面讲过的`dp[i][j]`的定义，`word1[i - 1]` 与 `word2[j - 1]`相等了，那么就不用编辑了，以下标i-2为结尾的字符串word1和以下标j-2为结尾的字符串`word2`的最近编辑距离`dp[i - 1][j - 1]`就是 `dp[i][j]`了。 -在下面的讲解中，如果哪里看不懂，就回想一下dp[i][j]的定义，就明白了。 +在下面的讲解中，如果哪里看不懂，就回想一下`dp[i][j]`的定义，就明白了。 -**在整个动规的过程中，最为关键就是正确理解dp[i][j]的定义！** +**在整个动规的过程中，最为关键就是正确理解`dp[i][j]`的定义！** -if (word1[i - 1] != word2[j - 1])，此时就需要编辑了，如何编辑呢？ -操作一：word1增加一个元素，使其word1[i - 1]与word2[j - 1]相同，那么就是以下标i-2为结尾的word1 与 i-1为结尾的word2的最近编辑距离 加上一个增加元素的操作。 +`if (word1[i - 1] != word2[j - 1])`，此时就需要编辑了，如何编辑呢？ -即 dp[i][j] = dp[i - 1][j] + 1; +操作一：word1增加一个元素，使其word1[i - 1]与word2[j - 1]相同，那么就是以下标i-2为结尾的word1 与 j-1为结尾的word2的最近编辑距离 加上一个增加元素的操作。 + +即 `dp[i][j] = dp[i - 1][j] + 1;` 操作二：word2添加一个元素，使其word1[i - 1]与word2[j - 1]相同，那么就是以下标i-1为结尾的word1 与 j-2为结尾的word2的最近编辑距离 加上一个增加元素的操作。 -即 dp[i][j] = dp[i][j - 1] + 1; +即 `dp[i][j] = dp[i][j - 1] + 1;` 这里有同学发现了，怎么都是添加元素，删除元素去哪了。 -**word2添加一个元素，相当于word1删除一个元素**，例如 word1 = "ad" ，word2 = "a"，word2添加一个元素d，也就是相当于word1删除一个元素d，操作数是一样！ +**word2添加一个元素，相当于word1删除一个元素**，例如 `word1 = "ad" ，word2 = "a"`，`word1`删除元素`'d'`，`word2`添加一个元素`'d'`，变成`word1="a", word2="ad"`， 最终的操作数是一样！ dp数组如下图所示意的： -操作三：替换元素，word1替换word1[i - 1]，使其与word2[j - 1]相同，此时不用增加元素，那么以下标i-2为结尾的word1 与 j-2为结尾的word2的最近编辑距离 加上一个替换元素的操作。 +``` + a a d + +-----+-----+ +-----+-----+-----+ + | 0 | 1 | | 0 | 1 | 2 | + +-----+-----+ ===> +-----+-----+-----+ + a | 1 | 0 | a | 1 | 0 | 1 | + +-----+-----+ +-----+-----+-----+ + d | 2 | 1 | + +-----+-----+ +``` -即 dp[i][j] = dp[i - 1][j - 1] + 1; +操作三：替换元素，`word1`替换`word1[i - 1]`，使其与`word2[j - 1]`相同，此时不用增加元素，那么以下标`i-2`为结尾的`word1` 与 `j-2`为结尾的`word2`的最近编辑距离 加上一个替换元素的操作。 -综上，当 if (word1[i - 1] != word2[j - 1]) 时取最小的，即：dp[i][j] = min({dp[i - 1][j - 1], dp[i - 1][j], dp[i][j - 1]}) + 1; +即 `dp[i][j] = dp[i - 1][j - 1] + 1;` + +综上，当 `if (word1[i - 1] != word2[j - 1])` 时取最小的，即：`dp[i][j] = min({dp[i - 1][j - 1], dp[i - 1][j], dp[i][j - 1]}) + 1;` 递归公式代码如下： @@ -114,9 +132,12 @@ else { } ``` -3. dp数组如何初始化 +--- -在回顾一下dp[i][j]的定义。 +### 3. dp数组如何初始化 + + +再回顾一下dp[i][j]的定义： **dp[i][j] 表示以下标i-1为结尾的字符串word1，和以下标j-1为结尾的字符串word2，最近编辑距离为dp[i][j]**。 @@ -135,14 +156,16 @@ for (int i = 0; i <= word1.size(); i++) dp[i][0] = i; for (int j = 0; j <= word2.size(); j++) dp[0][j] = j; ``` -4. 确定遍历顺序 +----------------------- + +### 4. 确定遍历顺序 从如下四个递推公式： -* dp[i][j] = dp[i - 1][j - 1] -* dp[i][j] = dp[i - 1][j - 1] + 1 -* dp[i][j] = dp[i][j - 1] + 1 -* dp[i][j] = dp[i - 1][j] + 1 +* `dp[i][j] = dp[i - 1][j - 1]` +* `dp[i][j] = dp[i - 1][j - 1] + 1` +* `dp[i][j] = dp[i][j - 1] + 1` +* `dp[i][j] = dp[i - 1][j] + 1` 可以看出dp[i][j]是依赖左方，上方和左上方元素的，如图： @@ -164,10 +187,12 @@ for (int i = 1; i <= word1.size(); i++) { } } ``` +----------------------- -5. 举例推导dp数组 +### 5. 举例推导dp数组 -以示例1，输入：word1 = "horse", word2 = "ros"为例，dp矩阵状态图如下： + +以示例1为例，输入：`word1 = "horse", word2 = "ros"`为例，dp矩阵状态图如下： ![72.编辑距离1](https://img-blog.csdnimg.cn/20210114162132300.jpg) @@ -195,7 +220,7 @@ public: }; ``` - +----------------------- ## 其他语言版本 From 7fd07921a8d8470f9f597b7162b34e1b8c5d0b80 Mon Sep 17 00:00:00 2001 From: Yang Date: Mon, 14 Jun 2021 21:00:34 -0400 Subject: [PATCH 092/122] =?UTF-8?q?Update=200115.=E4=B8=8D=E5=90=8C?= =?UTF-8?q?=E7=9A=84=E5=AD=90=E5=BA=8F=E5=88=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add Java solution --- problems/0115.不同的子序列.md | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/problems/0115.不同的子序列.md b/problems/0115.不同的子序列.md index e54389aa..d3bc6d97 100644 --- a/problems/0115.不同的子序列.md +++ b/problems/0115.不同的子序列.md @@ -145,7 +145,28 @@ public: Java： - +```java +class Solution { + public int numDistinct(String s, String t) { + int[][] dp = new int[s.length() + 1][t.length() + 1]; + for (int i = 0; i < s.length() + 1; i++) { + dp[i][0] = 1; + } + + for (int i = 1; i < s.length() + 1; i++) { + for (int j = 1; j < t.length() + 1; j++) { + if (s.charAt(i - 1) == t.charAt(j - 1)) { + dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j]; + }else{ + dp[i][j] = dp[i - 1][j]; + } + } + } + + return dp[s.length()][t.length()]; + } +} +``` Python： ```python From b1407c02a48f53dde729dea361c41ab283e72fb1 Mon Sep 17 00:00:00 2001 From: Yang Date: Mon, 14 Jun 2021 22:09:33 -0400 Subject: [PATCH 093/122] =?UTF-8?q?Update=200583.=E4=B8=A4=E4=B8=AA?= =?UTF-8?q?=E5=AD=97=E7=AC=A6=E4=B8=B2=E7=9A=84=E5=88=A0=E9=99=A4=E6=93=8D?= =?UTF-8?q?=E4=BD=9C.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add Java solution --- .../0583.两个字符串的删除操作.md | 22 +++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/problems/0583.两个字符串的删除操作.md b/problems/0583.两个字符串的删除操作.md index 0b32d129..ee1fbc5f 100644 --- a/problems/0583.两个字符串的删除操作.md +++ b/problems/0583.两个字符串的删除操作.md @@ -104,6 +104,28 @@ public: Java： +```java +class Solution { + public int minDistance(String word1, String word2) { + int[][] dp = new int[word1.length() + 1][word2.length() + 1]; + for (int i = 0; i < word1.length() + 1; i++) dp[i][0] = i; + for (int j = 0; j < word2.length() + 1; j++) dp[0][j] = j; + + for (int i = 1; i < word1.length() + 1; i++) { + for (int j = 1; j < word2.length() + 1; j++) { + if (word1.charAt(i - 1) == word2.charAt(j - 1)) { + dp[i][j] = dp[i - 1][j - 1]; + }else{ + dp[i][j] = Math.min(dp[i - 1][j - 1] + 2, + Math.min(dp[i - 1][j] + 1, dp[i][j - 1] + 1)); + } + } + } + + return dp[word1.length()][word2.length()]; + } +} +``` Python： From e1bbd30d8ec02cab5b1c11dfb360f9252c809382 Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Tue, 15 Jun 2021 16:01:10 +0800 Subject: [PATCH 094/122] =?UTF-8?q?update=20=E5=9B=9B=E6=95=B0=E7=9B=B8?= =?UTF-8?q?=E5=8A=A0II=EF=BC=8C=E6=B7=BB=E5=8A=A0=E4=BA=86=E4=B8=80?= =?UTF-8?q?=E4=B8=AA=E6=9B=B4=E5=8A=A0=E7=AE=80=E6=B4=81=E7=9A=84python?= =?UTF-8?q?=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0454.四数相加II.md | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0454.四数相加II.md b/problems/0454.四数相加II.md index 835178dd..0621ab5b 100644 --- a/problems/0454.四数相加II.md +++ b/problems/0454.四数相加II.md @@ -120,7 +120,7 @@ class Solution { Python： -``` +```python class Solution(object): def fourSumCount(self, nums1, nums2, nums3, nums4): """ @@ -147,7 +147,31 @@ class Solution(object): if key in hashmap: count += hashmap[key] return count + +# 下面这个写法更为简洁，但是表达的是同样的算法 +# class Solution: +# def fourSumCount(self, nums1: List[int], nums2: List[int], nums3: List[int], nums4: List[int]) -> int: +# from collections import defaultdict + +# hashmap = defaultdict(int) + +# for x1 in nums1: +# for x2 in nums2: +# hashmap[x1+x2] += 1 + +# count=0 +# for x3 in nums3: +# for x4 in nums4: +# key = -x3-x4 +# value = hashmap.get(key) + + # dict的get方法会返回None（key不存在）或者key对应的value + # 所以如果value==0，就会继续执行or，count+0，否则就会直接加value + # 这样就不用去写if判断了 + +# count += value or 0 +# return count ``` From 999bbae8c24ed0dae872603ea0c0aab0ae1d7afe Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Tue, 15 Jun 2021 16:13:23 +0800 Subject: [PATCH 095/122] =?UTF-8?q?=E5=B0=86python3=E7=9A=84=E4=BB=A3?= =?UTF-8?q?=E7=A0=81=E5=8C=BA=E6=A0=87=E8=AF=86=E6=94=B9=E4=B8=BApython?= =?UTF-8?q?=EF=BC=8C=E5=9B=A0=E4=B8=BAtypora=E4=B8=8D=E8=83=BD=E8=AF=86?= =?UTF-8?q?=E5=88=ABpython3=EF=BC=8C=E5=90=8C=E6=97=B6=E6=94=B9=E4=B8=BApy?= =?UTF-8?q?thon=E5=AF=B9=E9=AB=98=E4=BA=AE=E9=98=85=E8=AF=BB=E5=B9=B6?= =?UTF-8?q?=E6=B2=A1=E6=9C=89=E5=BD=B1=E5=93=8D=EF=BC=8C=E8=80=8C=E4=B8=94?= =?UTF-8?q?python=E5=AF=B9=E5=85=B6=E4=BB=96markdown=E8=BD=AF=E4=BB=B6?= =?UTF-8?q?=E7=9A=84=E5=85=BC=E5=AE=B9=E6=80=A7=E6=9B=B4=E5=A5=BD=E3=80=82?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0001.两数之和.md | 2 +- problems/0349.两个数组的交集.md | 2 +- problems/0707.设计链表.md | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/problems/0001.两数之和.md b/problems/0001.两数之和.md index 02e9996f..31a808b0 100644 --- a/problems/0001.两数之和.md +++ b/problems/0001.两数之和.md @@ -107,7 +107,7 @@ public int[] twoSum(int[] nums, int target) { Python： -```python3 +```python class Solution: def twoSum(self, nums: List[int], target: int) -> List[int]: hashmap={} diff --git a/problems/0349.两个数组的交集.md b/problems/0349.两个数组的交集.md index 090480a4..5c635d39 100644 --- a/problems/0349.两个数组的交集.md +++ b/problems/0349.两个数组的交集.md @@ -118,7 +118,7 @@ class Solution { ``` Python： -```python3 +```python class Solution: def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]: result_set = set() diff --git a/problems/0707.设计链表.md b/problems/0707.设计链表.md index 2fa1af29..2d096063 100644 --- a/problems/0707.设计链表.md +++ b/problems/0707.设计链表.md @@ -239,7 +239,7 @@ class MyLinkedList { ``` Python： -```python3 +```python # 单链表 class Node: From fb21a5727e249ce000d14edf59b291b6d099ce2b Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Tue, 15 Jun 2021 16:50:32 +0800 Subject: [PATCH 096/122] =?UTF-8?q?update=E8=B5=8E=E9=87=91=E4=BF=A1?= =?UTF-8?q?=EF=BC=8C=E6=B7=BB=E5=8A=A0=E4=BA=86=E4=BD=BF=E7=94=A8=E6=95=B0?= =?UTF-8?q?=E7=BB=84=E4=BD=9C=E4=B8=BA=E5=93=88=E5=B8=8C=E8=A1=A8=E5=92=8C?= =?UTF-8?q?=E4=BD=BF=E7=94=A8defaultdict=E4=B8=A4=E7=A7=8D=E5=86=99?= =?UTF-8?q?=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0383.赎金信.md | 49 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 47 insertions(+), 2 deletions(-) diff --git a/problems/0383.赎金信.md b/problems/0383.赎金信.md index 23e2c5fd..5374a08f 100644 --- a/problems/0383.赎金信.md +++ b/problems/0383.赎金信.md @@ -135,8 +135,52 @@ class Solution { ``` -Python： -```py +Python写法一（使用数组作为哈希表）： + +```python +class Solution: + def canConstruct(self, ransomNote: str, magazine: str) -> bool: + + arr = [0] * 26 + + for x in magazine: + arr[ord(x) - ord('a')] += 1 + + for x in ransomNote: + if arr[ord(x) - ord('a')] == 0: + return False + else: + arr[ord(x) - ord('a')] -= 1 + + return True +``` + +Python写法二（使用defaultdict）： + +```python +class Solution: + def canConstruct(self, ransomNote: str, magazine: str) -> bool: + + from collections import defaultdict + + hashmap = defaultdict(int) + + for x in magazine: + hashmap[x] += 1 + + for x in ransomNote: + value = hashmap.get(x) + if value is None or value == 0: + return False + else: + hashmap[x] -= 1 + + return True +``` + +Python写法三： + +```python class Solution(object): def canConstruct(self, ransomNote, magazine): """ @@ -166,6 +210,7 @@ class Solution(object): ``` Go： + ```go func canConstruct(ransomNote string, magazine string) bool { record := make([]int, 26) From c79cc4845411209b7ce143ebc4f98adfd969b2b2 Mon Sep 17 00:00:00 2001 From: yff-1996 Date: Tue, 15 Jun 2021 16:19:01 +0800 Subject: [PATCH 097/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00151.=E7=BF=BB?= =?UTF-8?q?=E8=BD=AC=E5=AD=97=E7=AC=A6=E4=B8=B2=E9=87=8C=E7=9A=84=E5=8D=95?= =?UTF-8?q?=E8=AF=8D=20Python=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0151.翻转字符串里的单词.md | 51 ++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index d76734e4..a174d550 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -318,6 +318,57 @@ class Solution { Python： +```Python3 +class Solution: + #1.去除多余的空格 + def trim_spaces(self,s): + n=len(s) + left=0 + right=n-1 + + while left<=right and s[left]==' ': #去除开头的空格 + left+=1 + while left<=right and s[right]==' ': #去除结尾的空格 + right=right-1 + tmp=[] + while left<=right: #去除单词中间多余的空格 + if s[left]!=' ': + tmp.append(s[left]) + elif tmp[-1]!=' ': #当前位置是空格，但是相邻的上一个位置不是空格，则该空格是合理的 + tmp.append(s[left]) + left+=1 + return tmp +#2.翻转字符数组 + def reverse_string(self,nums,left,right): + while left Date: Tue, 15 Jun 2021 17:35:31 +0800 Subject: [PATCH 098/122] =?UTF-8?q?0435.=E6=97=A0=E9=87=8D=E5=8F=A0?= =?UTF-8?q?=E5=8C=BA=E9=97=B4.md=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0435.无重叠区间.md | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/problems/0435.无重叠区间.md b/problems/0435.无重叠区间.md index 248526a1..23ee9f94 100644 --- a/problems/0435.无重叠区间.md +++ b/problems/0435.无重叠区间.md @@ -228,7 +228,27 @@ class Solution: Go： +Javascript: +```Javascript +var eraseOverlapIntervals = function(intervals) { + intervals.sort((a, b) => { + return a[1] - b[1] + }) + let count = 1 + let end = intervals[0][1] + + for(let i = 1; i < intervals.length; i++) { + let interval = intervals[i] + if(interval[0] >= right) { + end = interval[1] + count += 1 + } + } + + return intervals.length - count +}; +``` ----------------------- From 3a2ab58846f8071e704a0043600f457bfee70277 Mon Sep 17 00:00:00 2001 From: yff-1996 Date: Tue, 15 Jun 2021 18:42:59 +0800 Subject: [PATCH 099/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A0151.=E7=BF=BB?= =?UTF-8?q?=E8=BD=AC=E5=AD=97=E7=AC=A6=E4=B8=B2=E9=87=8C=E7=9A=84=E5=8D=95?= =?UTF-8?q?=E8=AF=8D=20python=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0151.翻转字符串里的单词.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index a174d550..c76ff0e1 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -359,10 +359,10 @@ class Solution: return None #4.翻转字符串里的单词 - def reverseWords(self, s): #测试用例："the sky is blue - l = self.trim_spaces(s) #输出："the sky is blue" - self.reverse_string( l, 0, len(l) - 1) #输出："blue is sky the" - self.reverse_each_word(l) #输出："blue is sky the" + def reverseWords(self, s): #测试用例："the sky is blue" + l = self.trim_spaces(s) #输出：['t', 'h', 'e', ' ', 's', 'k', 'y', ' ', 'i', 's', ' ', 'b', 'l', 'u', 'e' + self.reverse_string( l, 0, len(l) - 1) #输出：['e', 'u', 'l', 'b', ' ', 's', 'i', ' ', 'y', 'k', 's', ' ', 'e', 'h', 't'] + self.reverse_each_word(l) #输出：['b', 'l', 'u', 'e', ' ', 'i', 's', ' ', 's', 'k', 'y', ' ', 't', 'h', 'e'] return ''.join(l) #输出：blue is sky the From 7f76ec27103666f6003c0c8ed9b40c1432469d56 Mon Sep 17 00:00:00 2001 From: youngyangyang04 <826123027@qq.com> Date: Tue, 15 Jun 2021 20:07:14 +0800 Subject: [PATCH 100/122] Update --- problems/0344.反转字符串.md | 20 +++++++++----------- problems/0541.反转字符串II.md | 8 ++++---- 2 files changed, 13 insertions(+), 15 deletions(-) diff --git a/problems/0344.反转字符串.md b/problems/0344.反转字符串.md index 1b86e847..fd395ce6 100644 --- a/problems/0344.反转字符串.md +++ b/problems/0344.反转字符串.md @@ -20,14 +20,13 @@ https://leetcode-cn.com/problems/reverse-string/ 你可以假设数组中的所有字符都是 ASCII 码表中的可打印字符。 -示例 1： +示例 1： +输入：["h","e","l","l","o"] +输出：["o","l","l","e","h"] -输入：["h","e","l","l","o"] -输出：["o","l","l","e","h"] -示例 2： - -输入：["H","a","n","n","a","h"] -输出：["h","a","n","n","a","H"] +示例 2： +输入：["H","a","n","n","a","h"] +输出：["h","a","n","n","a","H"] # 思路 @@ -56,7 +55,7 @@ https://leetcode-cn.com/problems/reverse-string/ 接下来再来讲一下如何解决反转字符串的问题。 -大家应该还记得，我们已经讲过了[206.反转链表](https://mp.weixin.qq.com/s/pnvVP-0ZM7epB8y3w_Njwg)。 +大家应该还记得，我们已经讲过了[206.反转链表](https://mp.weixin.qq.com/s/ckEvIVGcNLfrz6OLOMoT0A)。 在反转链表中，使用了双指针的方法。 @@ -64,7 +63,7 @@ https://leetcode-cn.com/problems/reverse-string/ 因为字符串也是一种数组，所以元素在内存中是连续分布，这就决定了反转链表和反转字符串方式上还是有所差异的。 -如果对数组和链表原理不清楚的同学，可以看这两篇，[关于链表，你该了解这些！](https://mp.weixin.qq.com/s/ntlZbEdKgnFQKZkSUAOSpQ)，[必须掌握的数组理论知识](https://mp.weixin.qq.com/s/X7R55wSENyY62le0Fiawsg)。 +如果对数组和链表原理不清楚的同学，可以看这两篇，[关于链表，你该了解这些！](https://mp.weixin.qq.com/s/fDGMmLrW7ZHlzkzlf_dZkw)，[必须掌握的数组理论知识](https://mp.weixin.qq.com/s/c2KABb-Qgg66HrGf8z-8Og)。 对于字符串，我们定义两个指针（也可以说是索引下表），一个从字符串前面，一个从字符串后面，两个指针同时向中间移动，并交换元素。 @@ -119,8 +118,7 @@ s[i] ^= s[j]; 相信大家本着我所讲述的原则来做字符串相关的题目，在选择库函数的角度上会有所原则，也会有所收获。 - -## C++代码 +C++代码如下： ```C++ class Solution { diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 00581fc0..3f7767fd 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -22,8 +22,8 @@ https://leetcode-cn.com/problems/reverse-string-ii/ 示例: -输入: s = "abcdefg", k = 2 -输出: "bacdfeg" +输入: s = "abcdefg", k = 2 +输出: "bacdfeg" # 思路 @@ -38,7 +38,7 @@ https://leetcode-cn.com/problems/reverse-string-ii/ **所以当需要固定规律一段一段去处理字符串的时候，要想想在在for循环的表达式上做做文章。** 性能如下： - + 那么这里具体反转的逻辑我们要不要使用库函数呢，其实用不用都可以，使用reverse来实现反转也没毛病，毕竟不是解题关键部分。 @@ -65,7 +65,7 @@ public: }; ``` -那么我们也可以实现自己的reverse函数，其实和题目[344. 反转字符串](https://mp.weixin.qq.com/s/X02S61WCYiCEhaik6VUpFA)道理是一样的。 +那么我们也可以实现自己的reverse函数，其实和题目[344. 反转字符串](https://mp.weixin.qq.com/s/_rNm66OJVl92gBDIbGpA3w)道理是一样的。 下面我实现的reverse函数区间是左闭右闭区间，代码如下： From b3eacc519bbe2e4f7ce1903dcb1eb7f740dfe535 Mon Sep 17 00:00:00 2001 From: NevS <1173325467@qq.com> Date: Tue, 15 Jun 2021 21:11:42 +0800 Subject: [PATCH 101/122] =?UTF-8?q?=E6=9B=B4=E6=96=B0=20=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=E7=9A=84=E9=80=92=E5=BD=92=E9=81=8D=E5=8E=86=20go?= =?UTF-8?q?=E7=89=88=E6=9C=AC=E7=9A=84=E4=BB=A3=E7=A0=81=E6=A0=BC=E5=BC=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/二叉树的递归遍历.md | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/problems/二叉树的递归遍历.md b/problems/二叉树的递归遍历.md index f2072e30..68f17257 100644 --- a/problems/二叉树的递归遍历.md +++ b/problems/二叉树的递归遍历.md @@ -221,12 +221,12 @@ class Solution: Go： 前序遍历: -``` +```go func PreorderTraversal(root *TreeNode) (res []int) { var traversal func(node *TreeNode) traversal = func(node *TreeNode) { if node == nil { - return + return } res = append(res,node.Val) traversal(node.Left) @@ -239,12 +239,12 @@ func PreorderTraversal(root *TreeNode) (res []int) { ``` 中序遍历: -``` +```go func InorderTraversal(root *TreeNode) (res []int) { var traversal func(node *TreeNode) traversal = func(node *TreeNode) { if node == nil { - return + return } traversal(node.Left) res = append(res,node.Val) @@ -256,12 +256,12 @@ func InorderTraversal(root *TreeNode) (res []int) { ``` 后序遍历: -``` +```go func PostorderTraversal(root *TreeNode) (res []int) { var traversal func(node *TreeNode) traversal = func(node *TreeNode) { if node == nil { - return + return } traversal(node.Left) traversal(node.Right) From 11115137a8e1b51958954eba3899f052f380353e Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Tue, 15 Jun 2021 22:20:45 +0800 Subject: [PATCH 102/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00071.0501.=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=E4=B8=AD=E7=9A=84=E4=BC=97?= =?UTF-8?q?=E6=95=B0=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加0071.0501.二叉搜索树中的众数 go版本 --- problems/0501.二叉搜索树中的众数.md | 93 ++++++++++++++++++++ 1 file changed, 93 insertions(+) diff --git a/problems/0501.二叉搜索树中的众数.md b/problems/0501.二叉搜索树中的众数.md index dfd589ce..3ca7d892 100644 --- a/problems/0501.二叉搜索树中的众数.md +++ b/problems/0501.二叉搜索树中的众数.md @@ -428,7 +428,100 @@ class Solution: return self.res ``` Go： +暴力法（非BSL） +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func findMode(root *TreeNode) []int { + var history map[int]int + var maxValue int + var maxIndex int + var result []int + history=make(map[int]int) + traversal(root,history) + for k,value:=range history{ + if value>maxValue{ + maxValue=value + maxIndex=k + } + } + for k,value:=range history{ + if value==history[maxIndex]{ + result=append(result,k) + } + } + return result +} +func traversal(root *TreeNode,history map[int]int){ + if root.Left!=nil{ + traversal(root.Left,history) + } + if value,ok:=history[root.Val];ok{ + history[root.Val]=value+1 + }else{ + history[root.Val]=1 + } + if root.Right!=nil{ + traversal(root.Right,history) + } +} +``` + +计数法BSL（此代码在执行代码里能执行，但提交后报错，不知为何，思路是对的） + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + var count,maxCount int //统计计数 +func findMode(root *TreeNode) []int { + var result []int + var pre *TreeNode //前指针 + if root.Left==nil&&root.Right==nil{ + result=append(result,root.Val) + return result + } + traversal(root,&result,pre) + return result +} +func traversal(root *TreeNode,result *[]int,pre *TreeNode){//遍历统计 + //如果BSL中序遍历相邻的两个节点值相同，则统计频率；如果不相同，依据BSL中序遍历排好序的性质，重新计数 + if pre==nil{ + count=1 + }else if pre.Val==root.Val{ + count++ + }else { + count=1 + } + //如果统计的频率等于最大频率，则加入结果集；如果统计的频率大于最大频率，更新最大频率且重新将结果加入新的结果集中 + if count==maxCount{ + *result=append(*result,root.Val) + }else if count>maxCount{ + maxCount=count//重新赋值maxCount + *result=[]int{}//清空result中的内容 + *result=append(*result,root.Val) + } + pre=root//保存上一个的节点 + if root.Left!=nil{ + traversal(root.Left,result,pre) + } + if root.Right!=nil{ + traversal(root.Right,result,pre) + } +} +``` From 7221797cca0a206f469732c3dc5a06c3ef9d3885 Mon Sep 17 00:00:00 2001 From: yangxk201396 <54167260+yangxk201396@users.noreply.github.com> Date: Wed, 16 Jun 2021 02:06:23 +0800 Subject: [PATCH 103/122] =?UTF-8?q?Update=201005.K=E6=AC=A1=E5=8F=96?= =?UTF-8?q?=E5=8F=8D=E5=90=8E=E6=9C=80=E5=A4=A7=E5=8C=96=E7=9A=84=E6=95=B0?= =?UTF-8?q?=E7=BB=84=E5=92=8C.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 1005.K次取反后最大化的数组和.md Golang版本 --- ...1005.K次取反后最大化的数组和.md | 24 +++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/problems/1005.K次取反后最大化的数组和.md b/problems/1005.K次取反后最大化的数组和.md index 387de147..c3e99f7e 100644 --- a/problems/1005.K次取反后最大化的数组和.md +++ b/problems/1005.K次取反后最大化的数组和.md @@ -138,6 +138,30 @@ class Solution: ``` Go： +```Go +func largestSumAfterKNegations(nums []int, K int) int { + sort.Slice(nums, func(i, j int) bool { + return math.Abs(float64(nums[i])) > math.Abs(float64(nums[j])) + }) + + for i := 0; i < len(nums); i++ { + if K > 0 && nums[i] < 0 { + nums[i] = -nums[i] + K-- + } + } + + if K%2 == 1 { + nums[len(nums)-1] = -nums[len(nums)-1] + } + + result := 0 + for i := 0; i < len(nums); i++ { + result += nums[i] + } + return result +} +``` Javascript: From 1ad27bcb0d5bba938a5e27ce5c12ebb4eda9a81e Mon Sep 17 00:00:00 2001 From: callmePicacho <38685653+callmePicacho@users.noreply.github.com> Date: Wed, 16 Jun 2021 07:55:38 +0800 Subject: [PATCH 104/122] =?UTF-8?q?=E4=B8=BA"=E6=BB=91=E5=8A=A8=E7=AA=97?= =?UTF-8?q?=E5=8F=A3"=E7=B3=BB=E5=88=97=E7=9B=B8=E5=85=B3=E9=A2=98?= =?UTF-8?q?=E7=9B=AE=E6=8E=A8=E8=8D=90=E6=B7=BB=E5=8A=A0=E9=93=BE=E6=8E=A5?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0209.长度最小的子数组.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/problems/0209.长度最小的子数组.md b/problems/0209.长度最小的子数组.md index 90280451..42687514 100644 --- a/problems/0209.长度最小的子数组.md +++ b/problems/0209.长度最小的子数组.md @@ -109,7 +109,7 @@ public: }; ``` -时间复杂度：$O(n)$ +时间复杂度：$O(n)$ 空间复杂度：$O(1)$ **一些录友会疑惑为什么时间复杂度是O(n)**。 @@ -118,8 +118,8 @@ public: ## 相关题目推荐 -* 904.水果成篮 -* 76.最小覆盖子串 +* [904.水果成篮](https://leetcode-cn.com/problems/fruit-into-baskets/) +* [76.最小覆盖子串](https://leetcode-cn.com/problems/minimum-window-substring/) From 2ed2d8bf13e823df335492d806c6d069fa32b9ff Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Wed, 16 Jun 2021 08:10:13 +0800 Subject: [PATCH 105/122] =?UTF-8?q?0763.=E5=88=92=E5=88=86=E5=AD=97?= =?UTF-8?q?=E6=AF=8D=E5=8C=BA=E9=97=B4.md=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0763.划分字母区间.md | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/problems/0763.划分字母区间.md b/problems/0763.划分字母区间.md index bcdd71dc..1e2fcc03 100644 --- a/problems/0763.划分字母区间.md +++ b/problems/0763.划分字母区间.md @@ -128,7 +128,26 @@ class Solution: Go： - +Javascript: +```Javascript +var partitionLabels = function(s) { + let hash = {} + for(let i = 0; i < s.length; i++) { + hash[s[i]] = i + } + let result = [] + let left = 0 + let right = 0 + for(let i = 0; i < s.length; i++) { + right = Math.max(right, hash[s[i]]) + if(right === i) { + result.push(right - left + 1) + left = i + 1 + } + } + return result +}; +``` ----------------------- From 0bafb2d775466d18eec6b142163657ffe3a66b05 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:05:09 -0400 Subject: [PATCH 106/122] =?UTF-8?q?=E6=9B=B4=E6=94=B9=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20Java=20=E4=BB=A3=E7=A0=81=E6=A0=BC=E5=BC=8F.?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index e85d31b4..075bb5b1 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -214,7 +214,7 @@ int main() { Java： ```java - public static void main(String[] args) { + public static void main(String[] args) { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagWight = 4; From ecd98c9a79e1e3efbde2dc140d9adc7b2af93c3b Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:06:42 -0400 Subject: [PATCH 107/122] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20Python3=20=E5=AE=9E=E7=8E=B0=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index 075bb5b1..aee1a929 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -242,7 +242,24 @@ Java： Python： +```python +def test_1_wei_bag_problem(): + weight = [1, 3, 4] + value = [15, 20, 30] + bag_weight = 4 + # 初始化: 全为0 + dp = [0] * (bag_weight + 1) + # 先遍历物品, 再遍历背包容量 + for i in range(len(weight)): + for j in range(bag_weight, weight[i] - 1, -1): + # 递归公式 + dp[j] = max(dp[j], dp[j - weight[i]] + value[i]) + + print(dp) + +test_1_wei_bag_problem() +``` Go： ```go From 5dc2a0b745086c026e75cde53d898a67f9e98eb1 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:09:06 -0400 Subject: [PATCH 108/122] =?UTF-8?q?=E6=9B=B4=E6=94=B9=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20=E6=A0=BC=E5=BC=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 增加一个空行, 因为如果没有空行浏览器render文字就会有问题. --- problems/背包理论基础01背包-2.md | 1 + 1 file changed, 1 insertion(+) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index aee1a929..c8b80655 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -5,6 +5,7 @@

欢迎大家参与本项目，贡献其他语言版本的代码，拥抱开源，让更多学习算法的小伙伴们收益！

+ # 动态规划：关于01背包问题，你该了解这些！（滚动数组） 昨天[动态规划：关于01背包问题，你该了解这些！](https://mp.weixin.qq.com/s/FwIiPPmR18_AJO5eiidT6w)中是用二维dp数组来讲解01背包。 From 3746acd22b02e94945a20d9c2a69de788a0f016c Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:10:08 -0400 Subject: [PATCH 109/122] =?UTF-8?q?=E6=9B=B4=E6=96=B0=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 小typo. --- problems/背包理论基础01背包-2.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index c8b80655..48275908 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -36,7 +36,7 @@ **其实可以发现如果把dp[i - 1]那一层拷贝到dp[i]上，表达式完全可以是：dp[i][j] = max(dp[i][j], dp[i][j - weight[i]] + value[i]);** -**于其把dp[i - 1]这一层拷贝到dp[i]上，不如只用一个一维数组了**，只用dp[j]（一维数组，也可以理解是一个滚动数组）。 +**与其把dp[i - 1]这一层拷贝到dp[i]上，不如只用一个一维数组了**，只用dp[j]（一维数组，也可以理解是一个滚动数组）。 这就是滚动数组的由来，需要满足的条件是上一层可以重复利用，直接拷贝到当前层。 From a7d9d7aa23d2bb1d647d758b3ea1d65aef8e28e6 Mon Sep 17 00:00:00 2001 From: kok-s0s <2694308562@qq.com> Date: Wed, 16 Jun 2021 09:39:16 +0800 Subject: [PATCH 110/122] =?UTF-8?q?=E6=8F=90=E4=BA=A4=20=E3=80=8A=E4=BB=8E?= =?UTF-8?q?=E5=89=8D=E5=BA=8F=E4=B8=8E=E4=B8=AD=E5=BA=8F=E9=81=8D=E5=8E=86?= =?UTF-8?q?=E5=BA=8F=E5=88=97=E6=9E=84=E9=80=A0=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=E3=80=8BJavaScript=E7=89=88=E6=9C=AC=E7=9A=84=E4=BB=A3?= =?UTF-8?q?=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...中序与后序遍历序列构造二叉树.md | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/problems/0106.从中序与后序遍历序列构造二叉树.md b/problems/0106.从中序与后序遍历序列构造二叉树.md index 600a38e0..4c5a70a0 100644 --- a/problems/0106.从中序与后序遍历序列构造二叉树.md +++ b/problems/0106.从中序与后序遍历序列构造二叉树.md @@ -775,6 +775,20 @@ var buildTree = function(inorder, postorder) { }; ``` +从前序与中序遍历序列构造二叉树 + +```javascript +var buildTree = function(preorder, inorder) { + if(!preorder.length) + return null; + let root = new TreeNode(preorder[0]); + let mid = inorder.findIndex((number) => number === root.val); + root.left = buildTree(preorder.slice(1, mid + 1), inorder.slice(0, mid)); + root.right = buildTree(preorder.slice(mid + 1, preorder.length), inorder.slice(mid + 1, inorder.length)); + return root; +}; +``` + ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频：[代码随想录](https://space.bilibili.com/525438321) From 381c4e1bdf8c2b894e88817a79ffd388144c164c Mon Sep 17 00:00:00 2001 From: yangxk201396 <54167260+yangxk201396@users.noreply.github.com> Date: Wed, 16 Jun 2021 10:43:50 +0800 Subject: [PATCH 111/122] =?UTF-8?q?Update=200134.=E5=8A=A0=E6=B2=B9?= =?UTF-8?q?=E7=AB=99.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0134.加油站.md Golang 版本 --- problems/0134.加油站.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/problems/0134.加油站.md b/problems/0134.加油站.md index dfed2d96..9b660ea0 100644 --- a/problems/0134.加油站.md +++ b/problems/0134.加油站.md @@ -240,6 +240,25 @@ class Solution: ``` Go： +```go +func canCompleteCircuit(gas []int, cost []int) int { + curSum := 0 + totalSum := 0 + start := 0 + for i := 0; i < len(gas); i++ { + curSum += gas[i] - cost[i] + totalSum += gas[i] - cost[i] + if curSum < 0 { + start = i+1 + curSum = 0 + } + } + if totalSum < 0 { + return -1 + } + return start +} +``` Javascript: ```Javascript From d5b0e0ce587df7bb9c627bbad784b71d01098e36 Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Wed, 16 Jun 2021 14:49:07 +0200 Subject: [PATCH 112/122] =?UTF-8?q?Update=2093.=E5=A4=8D=E5=8E=9FIP?= =?UTF-8?q?=E5=9C=B0=E5=9D=80,=20=E6=B7=BB=E5=8A=A0Python3=E7=89=88?= =?UTF-8?q?=E6=9C=AC=EF=BC=8C=E7=94=A8=E4=BA=86=E6=96=B0=E7=9A=84=E5=89=AA?= =?UTF-8?q?=E6=9E=9D=E6=96=B9=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0093.复原IP地址.md | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md index a8b9a215..c47896d9 100644 --- a/problems/0093.复原IP地址.md +++ b/problems/0093.复原IP地址.md @@ -338,6 +338,46 @@ class Solution(object): return ans``` ``` +```python3 +class Solution: + def __init__(self) -> None: + self.s = "" + self.res = [] + + def isVaild(self, s: str) -> bool: + if len(s) > 1 and s[0] == "0": + return False + + if 0 <= int(s) <= 255: + return True + + return False + + def backTrack(self, path: List[str], start: int) -> None: + if start == len(self.s) and len(path) == 4: + self.res.append(".".join(path)) + return + + for end in range(start + 1, len(self.s) + 1): + # 剪枝 + # 保证切割完，s没有剩余的字符。 + if len(self.s) - end > 3 * (4 - len(path) - 1): + continue + if self.isVaild(self.s[start:end]): + # 在参数处，更新状态，实则创建一个新的变量 + # 不会影响当前的状态，当前的path变量没有改变 + # 因此递归完不用path.pop() + self.backTrack(path + [self.s[start:end]], end) + + def restoreIpAddresses(self, s: str) -> List[str]: + # prune + if len(s) > 3 * 4: + return [] + self.s = s + self.backTrack([], 0) + return self.res +``` + JavaScript： ```js From 2f514cd212303f53e8f30da93498b66e2df9577c Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Wed, 16 Jun 2021 23:11:56 +0800 Subject: [PATCH 113/122] =?UTF-8?q?=E6=B7=BB=E5=8A=A00235.=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=E7=9A=84=E6=9C=80=E8=BF=91?= =?UTF-8?q?=E5=85=AC=E5=85=B1=E7=A5=96=E5=85=88=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加0235.二叉搜索树的最近公共祖先 go版本 --- ...35.二叉搜索树的最近公共祖先.md | 48 +++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/problems/0235.二叉搜索树的最近公共祖先.md b/problems/0235.二叉搜索树的最近公共祖先.md index 15ff7af4..d78db42a 100644 --- a/problems/0235.二叉搜索树的最近公共祖先.md +++ b/problems/0235.二叉搜索树的最近公共祖先.md @@ -265,6 +265,54 @@ class Solution: else: return root ``` Go： +> BSL法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +//利用BSL的性质（前序遍历有序） +func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode { + if root==nil{return nil} + if root.Val>p.Val&&root.Val>q.Val{//当前节点的值大于给定的值，则说明满足条件的在左边 + return lowestCommonAncestor(root.Left,p,q) + }else if root.Val 普通法 + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +//递归会将值层层返回 +func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode { + //终止条件 + if root==nil||root.Val==p.Val||root.Val==q.Val{return root}//最后为空或者找到一个值时，就返回这个值 + //后序遍历 + findLeft:=lowestCommonAncestor(root.Left,p,q) + findRight:=lowestCommonAncestor(root.Right,p,q) + //处理单层逻辑 + if findLeft!=nil&&findRight!=nil{return root}//说明在root节点的两边 + if findLeft==nil{//左边没找到，就说明在右边找到了 + return findRight + }else {return findLeft} +} +``` + From 6994866773b176ff7154ff59f08a159278bfe1e3 Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Thu, 17 Jun 2021 08:15:32 +0800 Subject: [PATCH 114/122] =?UTF-8?q?0738.=E5=8D=95=E8=B0=83=E9=80=92?= =?UTF-8?q?=E5=A2=9E=E7=9A=84=E6=95=B0=E5=AD=97.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0738.单调递增的数字.md | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/problems/0738.单调递增的数字.md b/problems/0738.单调递增的数字.md index 5bddb234..41ca67be 100644 --- a/problems/0738.单调递增的数字.md +++ b/problems/0738.单调递增的数字.md @@ -163,7 +163,30 @@ class Solution: Go： +Javascript: +```Javascript +var monotoneIncreasingDigits = function(n) { + n = n.toString() + n = n.split('').map(item => { + return +item + }) + let flag = Infinity + for(let i = n.length - 1; i > 0; i--) { + if(n [i - 1] > n[i]) { + flag = i + n[i - 1] = n[i - 1] - 1 + n[i] = 9 + } + } + for(let i = flag; i < n.length; i++) { + n[i] = 9 + } + + n = n.join('') + return +n +}; +``` ----------------------- From 78b32e8c6c2c7708e1407c729ceebfeeca033f4d Mon Sep 17 00:00:00 2001 From: KailokFung Date: Thu, 17 Jun 2021 17:53:56 +0800 Subject: [PATCH 115/122] =?UTF-8?q?feat(0541):=20=E5=A2=9E=E5=8A=A0?= =?UTF-8?q?=E5=8F=A6=E4=B8=80=E7=A7=8DJava=E7=89=88=E6=9C=AC=E5=86=99?= =?UTF-8?q?=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0541.反转字符串II.md | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 00581fc0..4b3ed43b 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -103,6 +103,7 @@ public: Java： ```Java +//解法一 class Solution { public String reverseStr(String s, int k) { StringBuffer res = new StringBuffer(); @@ -128,6 +129,28 @@ class Solution { return res.toString(); } } + +//解法二（似乎更容易理解点） +//题目的意思其实概括为 每隔2k个反转前k个，尾数不够k个时候全部反转 +class Solution { + public String reverseStr(String s, int k) { + char[] ch = s.toCharArray(); + for(int i = 0; i < ch.length; i += 2 * k){ + int start = i; + //这里是判断尾数够不够k个来取决end指针的位置 + int end = Math.min(ch.length - 1, start + k - 1); + //用异或运算反转 + while(start < end){ + ch[start] ^= ch[end]; + ch[end] ^= ch[start]; + ch[start] ^= ch[end]; + start++; + end--; + } + } + return new String(ch); + } +} ``` Python： From 928b034e9bca9667949e22b589ece1b6f0b7a4d0 Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Thu, 17 Jun 2021 17:27:30 +0200 Subject: [PATCH 116/122] =?UTF-8?q?update=2037.=20=E8=A7=A3=E6=95=B0?= =?UTF-8?q?=E7=8B=AC:=20=E6=8F=90=E4=BE=9Bpython3=20=E7=89=88=E6=9C=AC?= =?UTF-8?q?=EF=BC=8C=E7=AE=80=E5=8C=96isValid=EF=BC=8C=20=E6=8F=90?= =?UTF-8?q?=E9=AB=98=E5=9B=9E=E6=BA=AF=E5=87=BD=E6=95=B0=E7=9A=84=E5=8F=AF?= =?UTF-8?q?=E8=AF=BB=E6=80=A7?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0037.解数独.md | 53 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/problems/0037.解数独.md b/problems/0037.解数独.md index 4eb60704..e43708b8 100644 --- a/problems/0037.解数独.md +++ b/problems/0037.解数独.md @@ -321,6 +321,59 @@ class Solution: backtrack(board) ``` +Python3: + +```python3 +class Solution: + def __init__(self) -> None: + self.board = [] + + def isValid(self, row: int, col: int, target: int) -> bool: + for idx in range(len(self.board)): + # 同列是否重复 + if self.board[idx][col] == str(target): + return False + # 同行是否重复 + if self.board[row][idx] == str(target): + return False + # 9宫格里是否重复 + box_row, box_col = (row // 3) * 3 + idx // 3, (col // 3) * 3 + idx % 3 + if self.board[box_row][box_col] == str(target): + return False + return True + + def getPlace(self) -> List[int]: + for row in range(len(self.board)): + for col in range(len(self.board)): + if self.board[row][col] == ".": + return [row, col] + return [-1, -1] + + def isSolved(self) -> bool: + row, col = self.getPlace() # 找个空位置 + + if row == -1 and col == -1: # 没有空位置，棋盘被填满的 + return True + + for i in range(1, 10): + if self.isValid(row, col, i): # 检查这个空位置放i，是否合适 + self.board[row][col] = str(i) # 放i + if self.isSolved(): # 合适，立刻返回, 填下一个空位置。 + return True + self.board[row][col] = "." # 不合适，回溯 + + return False # 空位置没法解决 + + def solveSudoku(self, board: List[List[str]]) -> None: + """ + Do not return anything, modify board in-place instead. + """ + if board is None or len(board) == 0: + return + self.board = board + self.isSolved() +``` + Go： Javascript: From 31ac198cd18ab1c1eb32665ddf52623c6e3b6c03 Mon Sep 17 00:00:00 2001 From: jojoo15 <75017412+jojoo15@users.noreply.github.com> Date: Thu, 17 Jun 2021 18:11:09 +0200 Subject: [PATCH 117/122] =?UTF-8?q?=E4=BC=98=E5=8C=96=200738.=E5=8D=95?= =?UTF-8?q?=E8=B0=83=E9=80=92=E5=A2=9E=E7=9A=84=E6=95=B0=E5=AD=97=20python?= =?UTF-8?q?3?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 优化 0738.单调递增的数字 python3 --- problems/0738.单调递增的数字.md | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/problems/0738.单调递增的数字.md b/problems/0738.单调递增的数字.md index 5bddb234..665f0fd6 100644 --- a/problems/0738.单调递增的数字.md +++ b/problems/0738.单调递增的数字.md @@ -147,18 +147,15 @@ class Solution { Python： -```python +```python3 class Solution: def monotoneIncreasingDigits(self, n: int) -> int: - strNum = list(str(n)) - flag = len(strNum) - for i in range(len(strNum) - 1, 0, -1): - if int(strNum[i]) < int(strNum[i - 1]): - strNum[i - 1] = str(int(strNum[i - 1]) - 1) - flag = i - for i in range(flag, len(strNum)): - strNum[i] = '9' - return int("".join(strNum)) + a = list(str(n)) + for i in range(len(a)-1,0,-1): + if int(a[i]) < int(a[i-1]): + a[i-1] = str(int(a[i-1]) - 1) + a[i:] = '9' * (len(a) - i) #python不需要设置flag值，直接按长度给9就好了 + return int("".join(a)) ``` Go： From ae3843698a156e7b7be6c0348df5ae882b645b06 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E8=97=A4=E9=9C=B2?= <080301087@163.com> Date: Fri, 18 Jun 2021 11:07:32 +0800 Subject: [PATCH 118/122] =?UTF-8?q?Update=200102.=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=E7=9A=84=E5=B1=82=E5=BA=8F=E9=81=8D=E5=8E=86.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0102.二叉树的层序遍历.md | 100 +++++++++++++++++++++- 1 file changed, 99 insertions(+), 1 deletion(-) diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md index 89d0dda7..341f4ba5 100644 --- a/problems/0102.二叉树的层序遍历.md +++ b/problems/0102.二叉树的层序遍历.md @@ -98,7 +98,7 @@ class Solution: out_list = [] while quene: - length = len(queue) # 这里一定要先求出队列的长度，不能用range(len(queue))，因为queue长度是变化的 + length = len(queue) in_list = [] for _ in range(length): curnode = queue.pop(0) # （默认移除列表最后一个元素）这里需要移除队列最头上的那个 @@ -627,6 +627,27 @@ public: } }; ``` +python代码： + +```python +class Solution: + def largestValues(self, root: TreeNode) -> List[int]: + if root is None: + return [] + queue = [root] + out_list = [] + while queue: + length = len(queue) + in_list = [] + for _ in range(length): + curnode = queue.pop(0) + in_list.append(curnode.val) + if curnode.left: queue.append(curnode.left) + if curnode.right: queue.append(curnode.right) + out_list.append(max(in_list)) + return out_list +``` + javascript代码： ```javascript @@ -712,6 +733,42 @@ public: }; ``` +python代码： + +```python +# 层序遍历解法 +class Solution: + def connect(self, root: 'Node') -> 'Node': + if not root: + return None + queue = [root] + while queue: + n = len(queue) + for i in range(n): + node = queue.pop(0) + if node.left: + queue.append(node.left) + if node.right: + queue.append(node.right) + if i == n - 1: + break + node.next = queue[0] + return root + +# 链表解法 +class Solution: + def connect(self, root: 'Node') -> 'Node': + first = root + while first: + cur = first + while cur: # 遍历每一层的节点 + if cur.left: cur.left.next = cur.right # 找左节点的next + if cur.right and cur.next: cur.right.next = cur.next.left # 找右节点的next + cur = cur.next # cur同层移动到下一节点 + first = first.left # 从本层扩展到下一层 + return root +``` + ## 117.填充每个节点的下一个右侧节点指针II 题目地址：https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node-ii/ @@ -753,7 +810,48 @@ public: } }; ``` +python代码： +```python +# 层序遍历解法 +class Solution: + def connect(self, root: 'Node') -> 'Node': + if not root: + return None + queue = [root] + while queue: # 遍历每一层 + length = len(queue) + tail = None # 每一层维护一个尾节点 + for i in range(length): # 遍历当前层 + curnode = queue.pop(0) + if tail: + tail.next = curnode # 让尾节点指向当前节点 + tail = curnode # 让当前节点成为尾节点 + if curnode.left : queue.append(curnode.left) + if curnode.right: queue.append(curnode.right) + return root + +# 链表解法 +class Solution: + def connect(self, root: 'Node') -> 'Node': + if not root: + return None + first = root + while first: # 遍历每一层 + dummyHead = Node(None) # 为下一行创建一个虚拟头节点，相当于下一行所有节点链表的头结点(每一层都会创建)； + tail = dummyHead # 为下一行维护一个尾节点指针（初始化是虚拟节点） + cur = first + while cur: # 遍历当前层的节点 + if cur.left: # 链接下一行的节点 + tail.next = cur.left + tail = tail.next + if cur.right: + tail.next = cur.right + tail = tail.next + cur = cur.next # cur同层移动到下一节点 + first = dummyHead.next # 此处为换行操作，更新到下一行 + return root +``` ## 总结 From 9d92c13420c5cd078ab2ba16e5cf39aa16252c21 Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Sat, 19 Jun 2021 14:05:20 +0800 Subject: [PATCH 119/122] =?UTF-8?q?0714.=E4=B9=B0=E5=8D=96=E8=82=A1?= =?UTF-8?q?=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA=E5=90=AB?= =?UTF-8?q?=E6=89=8B=E7=BB=AD=E8=B4=B9.md=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...买卖股票的最佳时机含手续费.md | 22 +++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/problems/0714.买卖股票的最佳时机含手续费.md b/problems/0714.买卖股票的最佳时机含手续费.md index abd20625..2e8f9208 100644 --- a/problems/0714.买卖股票的最佳时机含手续费.md +++ b/problems/0714.买卖股票的最佳时机含手续费.md @@ -217,7 +217,29 @@ class Solution: # 贪心思路 Go： +Javascript: +```Javascript +// 贪心思路 +var maxProfit = function(prices, fee) { + let result = 0 + let minPrice = prices[0] + for(let i = 1; i < prices.length; i++) { + if(prices[i] < minPrice) { + minPrice = prices[i] + } + if(prices[i] >= minPrice && prices[i] <= minPrice + fee) { + continue + } + if(prices[i] > minPrice + fee) { + result += prices[i] - minPrice - fee + // 买入和卖出只需要支付一次手续费 + minPrice = prices[i] -fee + } + } + return result +}; +``` ----------------------- From d6ab48534d80a506b0e60df8196c9b5e2c802b10 Mon Sep 17 00:00:00 2001 From: kok-s0s <2694308562@qq.com> Date: Sat, 19 Jun 2021 22:16:42 +0800 Subject: [PATCH 120/122] =?UTF-8?q?=E6=9C=80=E5=A4=A7=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91JavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0654.最大二叉树.md | 36 ++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/problems/0654.最大二叉树.md b/problems/0654.最大二叉树.md index f0d3e594..4e1e7a72 100644 --- a/problems/0654.最大二叉树.md +++ b/problems/0654.最大二叉树.md @@ -311,6 +311,42 @@ func findMax(nums []int) (index int){ } ``` +JavaScript版本 + +```javascript +/** + * Definition for a binary tree node. + * function TreeNode(val, left, right) { + * this.val = (val===undefined ? 0 : val) + * this.left = (left===undefined ? null : left) + * this.right = (right===undefined ? null : right) + * } + */ +/** + * @param {number[]} nums + * @return {TreeNode} + */ +var constructMaximumBinaryTree = function (nums) { + const BuildTree = (arr, left, right) => { + if (left > right) + return null; + let maxValue = -1; + let maxIndex = -1; + for (let i = left; i <= right; ++i) { + if (arr[i] > maxValue) { + maxValue = arr[i]; + maxIndex = i; + } + } + let root = new TreeNode(maxValue); + root.left = BuildTree(arr, left, maxIndex - 1); + root.right = BuildTree(arr, maxIndex + 1, right); + return root; + } + let root = BuildTree(nums, 0, nums.length - 1); + return root; +}; +``` From aa87376071b0f66897c18f74509a9c899c8ce858 Mon Sep 17 00:00:00 2001 From: youngyangyang04 <826123027@qq.com> Date: Mon, 21 Jun 2021 10:12:10 +0800 Subject: [PATCH 121/122] Update --- README.md | 4 ++ problems/0051.N皇后.md | 8 --- problems/0151.翻转字符串里的单词.md | 63 +++++++------------ problems/0160.相交链表.md | 2 + problems/剑指Offer05.替换空格.md | 32 ++++------ .../剑指Offer58-II.左旋转字符串.md | 35 +++++------ problems/栈与队列理论基础.md | 15 +---- 7 files changed, 60 insertions(+), 99 deletions(-) create mode 100644 problems/0160.相交链表.md diff --git a/README.md b/README.md index daef7c02..b9ee3a9e 100644 --- a/README.md +++ b/README.md @@ -125,6 +125,10 @@ 4. [马上秋招了，慌得很！](https://mp.weixin.qq.com/s/7q7W8Cb2-a5U5atZdOnOFA) 5. [Carl看了上百份简历，总结了这些！](https://mp.weixin.qq.com/s/sJa87MZD28piCOVMFkIbwQ) 6. [面试中遇到了发散性问题.....](https://mp.weixin.qq.com/s/SSonDxi2pjkSVwHNzZswng) +7. [英语到底重不重要！](https://mp.weixin.qq.com/s/1PRZiyF_-TVA-ipwDNjdKw) +8. [计算机专业要不要读研！](https://mp.weixin.qq.com/s/c9v1L3IjqiXtkNH7sOMAdg) +9. [秋招和提前批都越来越提前了....](https://mp.weixin.qq.com/s/SNFiRDx8CKyjhTPlys6ywQ) + ## 数组 diff --git a/problems/0051.N皇后.md b/problems/0051.N皇后.md index 5242fce2..fd2c7d0f 100644 --- a/problems/0051.N皇后.md +++ b/problems/0051.N皇后.md @@ -353,14 +353,6 @@ class Solution { } ``` -## 其他语言版本 - - -Java： - - -Python： - Go： ```Go diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index d76734e4..e092a717 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -16,19 +16,19 @@ https://leetcode-cn.com/problems/reverse-words-in-a-string/ 给定一个字符串，逐个翻转字符串中的每个单词。 -示例 1： -输入: "the sky is blue" -输出: "blue is sky the" +示例 1： +输入: "the sky is blue" +输出: "blue is sky the" -示例 2： -输入: "  hello world!  " -输出: "world! hello" -解释: 输入字符串可以在前面或者后面包含多余的空格，但是反转后的字符不能包括。 +示例 2： +输入: "  hello world!  " +输出: "world! hello" +解释: 输入字符串可以在前面或者后面包含多余的空格，但是反转后的字符不能包括。 -示例 3： -输入: "a good   example" -输出: "example good a" -解释: 如果两个单词间有多余的空格，将反转后单词间的空格减少到只含一个。 +示例 3： +输入: "a good   example" +输出: "example good a" +解释: 如果两个单词间有多余的空格，将反转后单词间的空格减少到只含一个。 # 思路 @@ -50,12 +50,15 @@ https://leetcode-cn.com/problems/reverse-words-in-a-string/ * 将整个字符串反转 * 将每个单词反转 -如动画所示： +举个例子，源字符串为："the sky is blue " -![151翻转字符串里的单词](https://tva1.sinaimg.cn/large/008eGmZEly1gp0kv5gl4mg30gy0c4nbp.gif) +* 移除多余空格 : "the sky is blue" +* 字符串反转："eulb si yks eht" +* 单词反转："blue is sky the" 这样我们就完成了翻转字符串里的单词。 + 思路很明确了，我们说一说代码的实现细节，就拿移除多余空格来说，一些同学会上来写如下代码： ```C++ @@ -80,13 +83,13 @@ void removeExtraSpaces(string& s) { 如果不仔细琢磨一下erase的时间复杂读，还以为以上的代码是O(n)的时间复杂度呢。 -想一下真正的时间复杂度是多少，一个erase本来就是O(n)的操作，erase实现原理题目：[数组：就移除个元素很难么？](https://mp.weixin.qq.com/s/wj0T-Xs88_FHJFwayElQlA)，最优的算法来移除元素也要O(n)。 +想一下真正的时间复杂度是多少，一个erase本来就是O(n)的操作，erase实现原理题目：[数组：就移除个元素很难么？](https://mp.weixin.qq.com/s/RMkulE4NIb6XsSX83ra-Ww)，最优的算法来移除元素也要O(n)。 erase操作上面还套了一个for循环，那么以上代码移除冗余空格的代码时间复杂度为O(n^2)。 那么使用双指针法来去移除空格，最后resize（重新设置）一下字符串的大小，就可以做到O(n)的时间复杂度。 -如果对这个操作比较生疏了，可以再看一下这篇文章：[数组：就移除个元素很难么？](https://mp.weixin.qq.com/s/wj0T-Xs88_FHJFwayElQlA)是如何移除元素的。 +如果对这个操作比较生疏了，可以再看一下这篇文章：[数组：就移除个元素很难么？](https://mp.weixin.qq.com/s/RMkulE4NIb6XsSX83ra-Ww)是如何移除元素的。 那么使用双指针来移除冗余空格代码如下： fastIndex走的快，slowIndex走的慢，最后slowIndex就标记着移除多余空格后新字符串的长度。 @@ -122,7 +125,7 @@ void removeExtraSpaces(string& s) { 此时我们已经实现了removeExtraSpaces函数来移除冗余空格。 -还做实现反转字符串的功能，支持反转字符串子区间，这个实现我们分别在[字符串：这道题目，使用库函数一行代码搞定](https://mp.weixin.qq.com/s/X02S61WCYiCEhaik6VUpFA)和[字符串：简单的反转还不够！](https://mp.weixin.qq.com/s/XGSk1GyPWhfqj2g7Cb1Vgw)里已经讲过了。 +还做实现反转字符串的功能，支持反转字符串子区间，这个实现我们分别在[344.反转字符串](https://mp.weixin.qq.com/s/_rNm66OJVl92gBDIbGpA3w)和[541.反转字符串II](https://mp.weixin.qq.com/s/pzXt6PQ029y7bJ9YZB2mVQ)里已经讲过了。 代码如下： @@ -135,11 +138,8 @@ void reverse(string& s, int start, int end) { } ``` -## 本题C++整体代码 +本题C++整体代码 -效率： - - ```C++ // 版本一 @@ -203,6 +203,7 @@ public: return s; } + // 当然这里的主函数reverseWords写的有一些冗余的，可以精简一些，精简之后的主函数为： /* 主函数简单写法 string reverseWords(string s) { removeExtraSpaces(s); @@ -220,25 +221,8 @@ public: }; ``` -当然这里的主函数reverseWords写的有一些冗余的，可以精简一些，精简之后的主函数为： - -```C++ -// 注意这里仅仅是主函数，其他函数和版本一一致 -string reverseWords(string s) { - removeExtraSpaces(s); - reverse(s, 0, s.size() - 1); - for(int i = 0; i < s.size(); i++) { - int j = i; - // 查找单词间的空格，翻转单词 - while(j < s.size() && s[j] != ' ') j++; - reverse(s, i, j - 1); - i = j; - } - return s; -} -``` - - +效率： + @@ -316,7 +300,6 @@ class Solution { } ``` -Python： Go： diff --git a/problems/0160.相交链表.md b/problems/0160.相交链表.md new file mode 100644 index 00000000..d26f66fd --- /dev/null +++ b/problems/0160.相交链表.md @@ -0,0 +1,2 @@ + +同：[链表：链表相交](./面试题02.07.链表相交.md) diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md index a4c0149f..f68d8e22 100644 --- a/problems/剑指Offer05.替换空格.md +++ b/problems/剑指Offer05.替换空格.md @@ -13,9 +13,9 @@ https://leetcode-cn.com/problems/ti-huan-kong-ge-lcof/ 请实现一个函数，把字符串 s 中的每个空格替换成"%20"。 -示例 1： -输入：s = "We are happy." -输出："We%20are%20happy." +示例 1： +输入：s = "We are happy." +输出："We%20are%20happy." # 思路 @@ -42,9 +42,9 @@ i指向新长度的末尾，j指向旧长度的末尾。 时间复杂度，空间复杂度均超过100%的用户。 - + -## C++代码 +C++代码如下： ```C++ class Solution { @@ -76,17 +76,17 @@ public: }; ``` -时间复杂度：O(n) -空间复杂度：O(1) +* 时间复杂度：O(n) +* 空间复杂度：O(1) 此时算上本题，我们已经做了七道双指针相关的题目了分别是： -* [27.移除元素](https://mp.weixin.qq.com/s/wj0T-Xs88_FHJFwayElQlA) -* [15.三数之和](https://mp.weixin.qq.com/s/r5cgZFu0tv4grBAexdcd8A) -* [18.四数之和](https://mp.weixin.qq.com/s/nQrcco8AZJV1pAOVjeIU_g) -* [206.翻转链表](https://mp.weixin.qq.com/s/pnvVP-0ZM7epB8y3w_Njwg) -* [142.环形链表II](https://mp.weixin.qq.com/s/_QVP3IkRZWx9zIpQRgajzA) -* [344.反转字符串](https://mp.weixin.qq.com/s/X02S61WCYiCEhaik6VUpFA) +* [27.移除元素](https://mp.weixin.qq.com/s/RMkulE4NIb6XsSX83ra-Ww) +* [15.三数之和](https://mp.weixin.qq.com/s/QfTNEByq1YlNSXRKEumwHg) +* [18.四数之和](https://mp.weixin.qq.com/s/SBU3THi1Kv6Sar7htqCB2Q) +* [206.翻转链表](https://mp.weixin.qq.com/s/ckEvIVGcNLfrz6OLOMoT0A) +* [142.环形链表II](https://mp.weixin.qq.com/s/gt_VH3hQTqNxyWcl1ECSbQ) +* [344.反转字符串](https://mp.weixin.qq.com/s/_rNm66OJVl92gBDIbGpA3w) # 拓展 @@ -121,10 +121,6 @@ for (int i = 0; i < a.size(); i++) { 所以想处理字符串，我们还是会定义一个string类型。 - - - - ## 其他语言版本 @@ -150,8 +146,6 @@ public static String replaceSpace(StringBuffer str) { } ``` -Python： - Go： ```go diff --git a/problems/剑指Offer58-II.左旋转字符串.md b/problems/剑指Offer58-II.左旋转字符串.md index 39c8382c..70c6f015 100644 --- a/problems/剑指Offer58-II.左旋转字符串.md +++ b/problems/剑指Offer58-II.左旋转字符串.md @@ -16,16 +16,16 @@ https://leetcode-cn.com/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/ 字符串的左旋转操作是把字符串前面的若干个字符转移到字符串的尾部。请定义一个函数实现字符串左旋转操作的功能。比如，输入字符串"abcdefg"和数字2，该函数将返回左旋转两位得到的结果"cdefgab"。 -示例 1： -输入: s = "abcdefg", k = 2 -输出: "cdefgab" +示例 1： +输入: s = "abcdefg", k = 2 +输出: "cdefgab" -示例 2： -输入: s = "lrloseumgh", k = 6 -输出: "umghlrlose" +示例 2： +输入: s = "lrloseumgh", k = 6 +输出: "umghlrlose" -限制： -1 <= k < s.length <= 10000 +限制： +1 <= k < s.length <= 10000 # 思路 @@ -34,7 +34,7 @@ https://leetcode-cn.com/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/ 不能使用额外空间的话，模拟在本串操作要实现左旋转字符串的功能还是有点困难的。 -那么我们可以想一下上一题目[字符串：花式反转还不够！](https://mp.weixin.qq.com/s/X3qpi2v5RSp08mO-W5Vicw)中讲过，使用整体反转+局部反转就可以实现，反转单词顺序的目的。 +那么我们可以想一下上一题目[字符串：花式反转还不够！](https://mp.weixin.qq.com/s/4j6vPFHkFAXnQhmSkq2X9g)中讲过，使用整体反转+局部反转就可以实现，反转单词顺序的目的。 这道题目也非常类似，依然可以通过局部反转+整体反转 达到左旋转的目的。 @@ -50,13 +50,13 @@ https://leetcode-cn.com/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/ 如图： - + 最终得到左旋2个单元的字符串：cdefgab 思路明确之后，那么代码实现就很简单了 -# C++代码 +C++代码如下： ```C++ class Solution { @@ -73,15 +73,16 @@ public: # 总结 + 此时我们已经反转好多次字符串了，来一起回顾一下吧。 -在这篇文章[字符串：这道题目，使用库函数一行代码搞定](https://mp.weixin.qq.com/s/X02S61WCYiCEhaik6VUpFA)，第一次讲到反转一个字符串应该怎么做，使用了双指针法。 +在这篇文章[344.反转字符串](https://mp.weixin.qq.com/s/_rNm66OJVl92gBDIbGpA3w)，第一次讲到反转一个字符串应该怎么做，使用了双指针法。 -然后发现[字符串：简单的反转还不够！](https://mp.weixin.qq.com/s/XGSk1GyPWhfqj2g7Cb1Vgw)，这里开始给反转加上了一些条件，当需要固定规律一段一段去处理字符串的时候，要想想在在for循环的表达式上做做文章。 +然后发现[541. 反转字符串II](https://mp.weixin.qq.com/s/pzXt6PQ029y7bJ9YZB2mVQ)，这里开始给反转加上了一些条件，当需要固定规律一段一段去处理字符串的时候，要想想在在for循环的表达式上做做文章。 -后来在[字符串：花式反转还不够！](https://mp.weixin.qq.com/s/X3qpi2v5RSp08mO-W5Vicw)中，要对一句话里的单词顺序进行反转，发现先整体反转再局部反转 是一个很妙的思路。 +后来在[151.翻转字符串里的单词](https://mp.weixin.qq.com/s/4j6vPFHkFAXnQhmSkq2X9g)中，要对一句话里的单词顺序进行反转，发现先整体反转再局部反转 是一个很妙的思路。 -最后再讲到本地，本题则是先局部反转再 整体反转，与[字符串：花式反转还不够！](https://mp.weixin.qq.com/s/X3qpi2v5RSp08mO-W5Vicw)类似，但是也是一种新的思路。 +最后再讲到本题，本题则是先局部反转再 整体反转，与[151.翻转字符串里的单词](https://mp.weixin.qq.com/s/4j6vPFHkFAXnQhmSkq2X9g)类似，但是也是一种新的思路。 好了，反转字符串一共就介绍到这里，相信大家此时对反转字符串的常见操作已经很了解了。 @@ -93,7 +94,6 @@ public: **如果想让这套题目有意义，就不要申请额外空间。** - ## 其他语言版本 Java： @@ -117,7 +117,6 @@ class Solution { } } ``` -Python： Go： @@ -151,4 +150,4 @@ func reverse(b []byte, left, right int){ * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频：[代码随想录](https://space.bilibili.com/525438321) * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ) -
\ No newline at end of file +
diff --git a/problems/栈与队列理论基础.md b/problems/栈与队列理论基础.md index 04f99981..db871a3c 100644 --- a/problems/栈与队列理论基础.md +++ b/problems/栈与队列理论基础.md @@ -85,20 +85,7 @@ std::queue> third; // 定义以list为底层容器的队列 所以STL 队列也不被归类为容器，而被归类为container adapter（ 容器适配器）。 -我这里讲的都是（clck）C++ 语言中情况， 使用其他语言的同学也要思考栈与队列的底层实现问题， 不要对数据结构的使用浅尝辄止，而要深挖起内部原理，才能夯实基础。 - - - -## 其他语言版本 - - -Java： - - -Python： - - -Go： +我这里讲的都是C++ 语言中情况， 使用其他语言的同学也要思考栈与队列的底层实现问题， 不要对数据结构的使用浅尝辄止，而要深挖起内部原理，才能夯实基础。 From 8496fe91463af3f016ed41d6eb7c072859f5b9ab Mon Sep 17 00:00:00 2001 From: fusunx <1102654482@qq.com> Date: Mon, 21 Jun 2021 10:48:55 +0800 Subject: [PATCH 122/122] =?UTF-8?q?0968.=E7=9B=91=E6=8E=A7=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=A0=91.md=20Javascript?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0968.监控二叉树.md | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/problems/0968.监控二叉树.md b/problems/0968.监控二叉树.md index 8f1a3fdb..a0eb5883 100644 --- a/problems/0968.监控二叉树.md +++ b/problems/0968.监控二叉树.md @@ -369,7 +369,42 @@ class Solution: ``` Go： +Javascript: +```Javascript +var minCameraCover = function(root) { + let result = 0 + function traversal(cur) { + if(cur === null) { + return 2 + } + let left = traversal(cur.left) + let right = traversal(cur.right) + + if(left === 2 && right === 2) { + return 0 + } + + if(left === 0 || right === 0) { + result++ + return 1 + } + + if(left === 1 || right === 1) { + return 2 + } + + return -1 + } + + if(traversal(root) === 0) { + result++ + } + + return result + +}; +``` -----------------------