From 17dd8f8499e6f5ab65d0529b3b9d9b388479b680 Mon Sep 17 00:00:00 2001 From: NevS <1173325467@qq.com> Date: Fri, 4 Jun 2021 00:20:25 +0800 Subject: [PATCH 01/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200541.=E5=8F=8D?= =?UTF-8?q?=E8=BD=AC=E5=AD=97=E7=AC=A6=E4=B8=B2II=20go=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0541.反转字符串II.md | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 6c8f3e94..00581fc0 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -164,6 +164,30 @@ class Solution(object): Go： +```go +func reverseStr(s string, k int) string { + ss := []byte(s) + length := len(s) + for i := 0; i < length; i += 2 * k { + if i + k <= length { + reverse(ss[i:i+k]) + } else { + reverse(ss[i:length]) + } + } + return string(ss) +} + +func reverse(b []byte) { + left := 0 + right := len(b) - 1 + for left < right { + b[left], b[right] = b[right], b[left] + left++ + right-- + } +} +``` javaScript: From e5ee38f826a9d230e1f474f1e4130fa564ac7674 Mon Sep 17 00:00:00 2001 From: SkyLazy <627770537@qq.com> Date: Fri, 4 Jun 2021 14:39:03 +0800 Subject: [PATCH 02/30] =?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 java 版本长度为1的时候也要考虑k的奇偶性才能直接return吧 --- 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 e57e26ad..5539aff8 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 @@ -102,7 +102,7 @@ Java： ```java class Solution { public int largestSumAfterKNegations(int[] A, int K) { - if (A.length == 1) return A[0]; + if (A.length == 1) return k % 2 == 0 ? A[0] : -A[0]; Arrays.sort(A); int sum = 0; int idx = 0; From b69ca00d2fc9a024145f6bc6d88de8ea88e3f3ab Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Fri, 4 Jun 2021 01:45:10 -0700 Subject: [PATCH 03/30] =?UTF-8?q?Update=200226.=E7=BF=BB=E8=BD=AC=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=A0=91.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0226.翻转二叉树.md | 50 ++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/problems/0226.翻转二叉树.md b/problems/0226.翻转二叉树.md index f48eefd2..2b628ec4 100644 --- a/problems/0226.翻转二叉树.md +++ b/problems/0226.翻转二叉树.md @@ -230,6 +230,56 @@ class Solution { Python： +> 递归法：前序遍历 +```python +class Solution: + def invertTree(self, root: TreeNode) -> TreeNode: + if not root: + return None + root.left, root.right = root.right, root.left #中 + self.invertTree(root.left) #左 + self.invertTree(root.right) #右 + return root +``` + +> 迭代法：深度优先遍历（前序遍历） +```python +class Solution: + def invertTree(self, root: TreeNode) -> TreeNode: + if not root: + return root + st = [] + st.append(root) + while st: + node = st.pop() + node.left, node.right = node.right, node.left #中 + if node.right: + st.append(node.right) #右 + if node.left: + st.append(node.left) #左 + return root +``` + +> 迭代法：广度优先遍历（层序遍历） +```python +import collections +class Solution: + def invertTree(self, root: TreeNode) -> TreeNode: + queue = collections.deque() #使用deque() + if root: + queue.append(root) + while queue: + size = len(queue) + for i in range(size): + node = queue.popleft() + node.left, node.right = node.right, node.left #节点处理 + if node.left: + queue.append(node.left) + if node.right: + queue.append(node.right) + return root +``` + Go： ```Go func invertTree(root *TreeNode) *TreeNode { From b655cb2730d1bc60f02d72cfd2918cb4d0789d3f Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Fri, 4 Jun 2021 02:10:07 -0700 Subject: [PATCH 04/30] =?UTF-8?q?Update=200101.=E5=AF=B9=E7=A7=B0=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=A0=91.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0101.对称二叉树.md | 72 ++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) diff --git a/problems/0101.对称二叉树.md b/problems/0101.对称二叉树.md index d8797d30..3dba1648 100644 --- a/problems/0101.对称二叉树.md +++ b/problems/0101.对称二叉树.md @@ -360,6 +360,78 @@ Java： Python： +> 递归法 +```python +class Solution: + def isSymmetric(self, root: TreeNode) -> bool: + if not root: + return True + return self.compare(root.left, root.right) + + def compare(self, left, right): + #首先排除空节点的情况 + if left == None and right != None: return False + elif left != None and right == None: return False + elif left == None and right == None: return True + #排除了空节点，再排除数值不相同的情况 + elif left.val != right.val: 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 + outside = self.compare(left.left, right.right) #左子树：左、 右子树：右 + inside = self.compare(left.right, right.left) #左子树：右、 右子树：左 + isSame = outside and inside #左子树：中、 右子树：中 （逻辑处理） + return isSame +``` + +> 迭代法： 使用队列 +```python +import collections +class Solution: + def isSymmetric(self, root: TreeNode) -> bool: + if not root: + return True + queue = collections.deque() + queue.append(root.left) #将左子树头结点加入队列 + queue.append(root.right) #将右子树头结点加入队列 + while queue: #接下来就要判断这这两个树是否相互翻转 + leftNode = queue.popleft() + rightNode = queue.popleft() + if not leftNode and not rightNode: #左节点为空、右节点为空，此时说明是对称的 + continue + + #左右一个节点不为空，或者都不为空但数值不相同，返回false + if not leftNode or not rightNode or leftNode.val != rightNode.val: + return False + queue.append(leftNode.left) #加入左节点左孩子 + queue.append(rightNode.right) #加入右节点右孩子 + queue.append(leftNode.right) #加入左节点右孩子 + queue.append(rightNode.left) #加入右节点左孩子 + return True +``` + +> 迭代法：使用栈 +```python +class Solution: + def isSymmetric(self, root: TreeNode) -> bool: + if not root: + return True + st = [] #这里改成了栈 + st.append(root.left) + st.append(root.right) + while st: + leftNode = st.pop() + rightNode = st.pop() + if not leftNode and not rightNode: + continue + if not leftNode or not rightNode or leftNode.val != rightNode.val: + return False + st.append(leftNode.left) + st.append(rightNode.right) + st.append(leftNode.right) + st.append(rightNode.left) + return True +``` Go： From c44a3165c4333530eac041aa1ede69088ed6462c Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Fri, 4 Jun 2021 03:08:41 -0700 Subject: [PATCH 05/30] =?UTF-8?q?Update=200104.=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=E7=9A=84=E6=9C=80=E5=A4=A7=E6=B7=B1=E5=BA=A6.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0104.二叉树的最大深度.md | 105 ++++++++++++++++++++++ 1 file changed, 105 insertions(+) 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 756afb68..4bf2b261 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 @@ -281,6 +281,111 @@ class Solution { Python： +104.二叉树的最大深度 +> 递归法： +```python +class Solution: + def maxDepth(self, root: TreeNode) -> int: + return self.getDepth(root) + + def getDepth(self, node): + if not node: + return 0 + leftDepth = self.getDepth(node.left) #左 + rightDepth = self.getDepth(node.right) #右 + depth = 1 + max(leftDepth, rightDepth) #中 + return depth +``` +> 递归法；精简代码 +```python +class Solution: + def maxDepth(self, root: TreeNode) -> int: + if not root: + return 0 + return 1 + max(self.maxDepth(root.left), self.maxDepth(root.right)) +``` + +> 迭代法： +```python +import collections +class Solution: + def maxDepth(self, root: TreeNode) -> int: + if not root: + return 0 + depth = 0 #记录深度 + queue = collections.deque() + queue.append(root) + while queue: + size = len(queue) + depth += 1 + for i in range(size): + node = queue.popleft() + if node.left: + queue.append(node.left) + if node.right: + queue.append(node.right) + return depth +``` + +559.N叉树的最大深度 +> 递归法： +```python +class Solution: + def maxDepth(self, root: 'Node') -> int: + if not root: + return 0 + depth = 0 + for i in range(len(root.children)): + depth = max(depth, self.maxDepth(root.children[i])) + return depth + 1 +``` + +> 迭代法： +```python +import collections +class Solution: + def maxDepth(self, root: 'Node') -> int: + queue = collections.deque() + if root: + queue.append(root) + depth = 0 #记录深度 + while queue: + size = len(queue) + depth += 1 + for i in range(size): + node = queue.popleft() + for j in range(len(node.children)): + if node.children[j]: + queue.append(node.children[j]) + return depth +``` + +> 使用栈来模拟后序遍历依然可以 +```python +class Solution: + def maxDepth(self, root: 'Node') -> int: + st = [] + if root: + st.append(root) + depth = 0 + result = 0 + while st: + node = st.pop() + if node != None: + st.append(node) #中 + st.append(None) + depth += 1 + for i in range(len(node.children)): #处理孩子 + if node.children[i]: + st.append(node.children[i]) + + else: + node = st.pop() + depth -= 1 + result = max(result, depth) + return result +``` + Go： From 7bf08e13586b38a14879d1c10668b29ee3145318 Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Sat, 5 Jun 2021 15:28:13 +0800 Subject: [PATCH 06/30] add python codes of binary tree's level order --- problems/0102.二叉树的层序遍历.md | 34 +++++++++++++++++++++++ 1 file changed, 34 insertions(+) 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 51bd8510..bfb78a43 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 @@ -80,6 +80,40 @@ public: } }; ``` +python代码： + +```python +# Definition for a binary tree node. +# class TreeNode: +# def __init__(self, val=0, left=None, right=None): +# self.val = val +# self.left = left +# self.right = right +class Solution: + def levelOrder(self, root: TreeNode) -> List[List[int]]: + if not root: + return [] + + quene = [root] + out_list = [] + + while quene: + in_list = [] + for i 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) + + out_list.append(in_list) + + return out_list +``` + + + javascript代码： ```javascript From 0ebd5f1a812f7d58d52b440f6b2721b8c8db95d7 Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:32:40 +0800 Subject: [PATCH 07/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A077.=20=E7=BB=84?= =?UTF-8?q?=E5=90=88=E4=BC=98=E5=8C=96JavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0077.组合优化.md | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/problems/0077.组合优化.md b/problems/0077.组合优化.md index 31acf4a5..d3e82f09 100644 --- a/problems/0077.组合优化.md +++ b/problems/0077.组合优化.md @@ -147,7 +147,7 @@ public: Java： -``` +```java class Solution { List> result = new ArrayList<>(); LinkedList path = new LinkedList<>(); @@ -220,6 +220,28 @@ func backtrack(n,k,start int,track []int){ } ``` +javaScript: + +```js +var combine = function(n, k) { + const res = [], path = []; + backtracking(n, k, 1); + return res; + function backtracking (n, k, i){ + const len = path.length; + if(len === k) { + res.push(Array.from(path)); + return; + } + for(let a = i; a <= n + len - k + 1; a++) { + path.push(a); + backtracking(n, k, a + 1); + path.pop(); + } + } +}; +``` + From faaa67c993869deac75fd0c36ba59f397aad582b Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:37:44 +0800 Subject: [PATCH 08/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=C2=B7216.=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8CIIIJavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0216.组合总和III.md | 42 ++++++++++++++++++++++++++++++-- 1 file changed, 40 insertions(+), 2 deletions(-) diff --git a/problems/0216.组合总和III.md b/problems/0216.组合总和III.md index 0aef7aec..9f75b23d 100644 --- a/problems/0216.组合总和III.md +++ b/problems/0216.组合总和III.md @@ -180,7 +180,7 @@ if (sum > targetSum) { // 剪枝操作 最后C++代码如下： -``` +```c++ class Solution { private: vector> result; // 存放结果集 @@ -262,7 +262,7 @@ class Solution { ``` Python： -```python3 +```py class Solution: def combinationSum3(self, k: int, n: int) -> List[List[int]]: res = [] #存放结果集 @@ -284,6 +284,44 @@ class Solution: Go： +javaScript: + +```js +// 等差数列 +var maxV = k => k * (9 + 10 - k) / 2; +var minV = k => k * (1 + k) / 2; +var combinationSum3 = function(k, n) { + if (k > 9 || k < 1) return []; + // if (n > maxV(k) || n < minV(k)) return []; + // if (n === maxV(k)) return [Array.from({length: k}).map((v, i) => 9 - i)]; + // if (n === minV(k)) return [Array.from({length: k}).map((v, i) => i + 1)]; + + const res = [], path = []; + backtracking(k, n, 1, 0); + return res; + function backtracking(k, n, i, sum){ + const len = path.length; + if (len > k || sum > n) return; + if (maxV(k - len) < n - sum) return; + if (minV(k - len) > n - sum) return; + + if(len === k && sum == n) { + res.push(Array.from(path)); + return; + } + + const min = Math.min(n - sum, 9 + len - k + 1); + + for(let a = i; a <= min; a++) { + path.push(a); + sum += a; + backtracking(k, n, a + 1, sum); + path.pop(); + sum -= a; + } + } +}; +``` From 7cbf0b1fff9675d507a686f4de7c08ef0c3d1394 Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:40:45 +0800 Subject: [PATCH 09/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A017.=E7=94=B5=E8=AF=9D?= =?UTF-8?q?=E5=8F=B7=E7=A0=81=E7=9A=84=E5=AD=97=E6=AF=8D=E7=BB=84=E5=90=88?= =?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/0017.电话号码的字母组合.md | 33 ++++++++++++++++++-- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index fa135d8d..aefee698 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -137,7 +137,7 @@ for (int i = 0; i < letters.size(); i++) { 关键地方都讲完了，按照[关于回溯算法，你该了解这些！](https://mp.weixin.qq.com/s/gjSgJbNbd1eAA5WkA-HeWw)中的回溯法模板，不难写出如下C++代码： -``` +```c++ // 版本一 class Solution { private: @@ -183,7 +183,7 @@ public: 一些写法，是把回溯的过程放在递归函数里了，例如如下代码，我可以写成这样：（注意注释中不一样的地方） -``` +```c++ // 版本二 class Solution { private: @@ -319,7 +319,7 @@ class Solution: python3： -```python3 +```py class Solution: def letterCombinations(self, digits: str) -> List[str]: self.s = "" @@ -342,6 +342,33 @@ class Solution: Go： +javaScript： + +```js +var letterCombinations = function(digits) { + const k = digits.length; + const map = ["","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"]; + if(!k) return []; + if(k === 1) return map[digits].split(""); + + const res = [], path = []; + backtracking(digits, k, 0); + return res; + + function backtracking(n, k, a) { + if(path.length === k) { + res.push(path.join("")); + return; + } + for(const v of map[n[a]]) { + path.push(v); + backtracking(n, k, a + 1); + path.pop(); + } + + } +}; +``` From d6955ebf03d534045271b74b879a937cdc32e0e0 Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:42:38 +0800 Subject: [PATCH 10/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A039.=20=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8CJavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0039.组合总和.md | 44 +++++++++++++++++------------------ 1 file changed, 22 insertions(+), 22 deletions(-) diff --git a/problems/0039.组合总和.md b/problems/0039.组合总和.md index e1023ec9..e3e4a117 100644 --- a/problems/0039.组合总和.md +++ b/problems/0039.组合总和.md @@ -286,30 +286,30 @@ class Solution: ``` Go： -JavaScript +JavaScript： + ```js -var strStr = function (haystack, needle) { - if (needle === '') { - return 0; - } - - let hayslen = haystack.length; - let needlen = needle.length; - - if (haystack === '' || hayslen < needlen) { - return -1; - } - - for (let i = 0; i <= hayslen - needlen; i++) { - if (haystack[i] === needle[0]) { - if (haystack.substr(i, needlen) === needle) { - return i; - } +var combinationSum = function(candidates, target) { + const res = [], path = []; + candidates.sort(); // 排序 + backtracking(0, 0); + return res; + function backtracking(j, sum) { + if (sum > target) return; + if (sum === target) { + res.push(Array.from(path)); + return; + } + for(let i = j; i < candidates.length; i++ ) { + const n = candidates[i]; + if(n > target - sum) continue; + path.push(n); + sum += n; + backtracking(i, sum); + path.pop(); + sum -= n; + } } - if (i === hayslen - needlen) { - return -1; - } - } }; ``` From ece55fe7efe84e4a76e1fd35d3046dd1aa67f2b5 Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:44:08 +0800 Subject: [PATCH 11/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A040.=E7=BB=84=E5=90=88?= =?UTF-8?q?=E6=80=BB=E5=92=8CIIJavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0040.组合总和II.md | 34 ++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/problems/0040.组合总和II.md b/problems/0040.组合总和II.md index 4d2996f5..a462b524 100644 --- a/problems/0040.组合总和II.md +++ b/problems/0040.组合总和II.md @@ -293,7 +293,7 @@ class Solution { } ``` Python： -```python3 +```py class Solution: def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]]: res = [] @@ -314,7 +314,39 @@ class Solution: ``` Go： +javaScript： +```js +/** + * @param {number[]} candidates + * @param {number} target + * @return {number[][]} + */ +var combinationSum2 = function(candidates, target) { + const res = []; path = [], len = candidates.length; + candidates.sort(); + backtracking(0, 0); + return res; + function backtracking(sum, i) { + if (sum > target) return; + if (sum === target) { + res.push(Array.from(path)); + return; + } + let f = -1; + for(let j = i; j < len; j++) { + const n = candidates[j]; + if(n > target - sum || n === f) continue; + path.push(n); + sum += n; + f = n; + backtracking(sum, j + 1); + path.pop(); + sum -= n; + } + } +}; +``` ----------------------- From b6b04cc035fa5b82d1a40cb9994f7cdb463bc466 Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:45:22 +0800 Subject: [PATCH 12/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A0131.=E5=88=86=E5=89=B2?= =?UTF-8?q?=E5=9B=9E=E6=96=87=E4=B8=B2JavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0131.分割回文串.md | 33 +++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/problems/0131.分割回文串.md b/problems/0131.分割回文串.md index c722af37..9d23fd13 100644 --- a/problems/0131.分割回文串.md +++ b/problems/0131.分割回文串.md @@ -292,7 +292,7 @@ class Solution { ``` Python： -```python3 +```py class Solution: def partition(self, s: str) -> List[List[str]]: res = [] @@ -313,7 +313,38 @@ class Solution: Go： +javaScript： +```js +/** + * @param {string} s + * @return {string[][]} + */ +const isPalindrome = (s, l, r) => { + for (let i = l, j = r; i < j; i++, j--) { + if(s[i] !== s[j]) return false; + } + return true; +} + +var partition = function(s) { + const res = [], path = [], len = s.length; + backtracking(0); + return res; + function backtracking(i) { + if(i >= len) { + res.push(Array.from(path)); + return; + } + for(let j = i; j < len; j++) { + if(!isPalindrome(s, i, j)) continue; + path.push(s.substr(i, j - i + 1)); + backtracking(j + 1); + path.pop(); + } + } +}; +``` ----------------------- From 533964af4b31bf1d08f45e626f562616ae12ca8b Mon Sep 17 00:00:00 2001 From: "qingyi.liu" Date: Sat, 5 Jun 2021 18:46:22 +0800 Subject: [PATCH 13/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A093.=E5=A4=8D=E5=8E=9FIP?= =?UTF-8?q?=E5=9C=B0=E5=9D=80JavaScript=C2=B7=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0093.复原IP地址.md | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md index 3c8e5d9d..a8b9a215 100644 --- a/problems/0093.复原IP地址.md +++ b/problems/0093.复原IP地址.md @@ -338,6 +338,35 @@ class Solution(object): return ans``` ``` +JavaScript： + +```js +/** + * @param {string} s + * @return {string[]} + */ +var restoreIpAddresses = function(s) { + const res = [], path = []; + backtracking(0, 0) + return res; + function backtracking(i) { + const len = path.length; + if(len > 4) return; + if(len === 4 && i === s.length) { + res.push(path.join(".")); + return; + } + for(let j = i; j < s.length; j++) { + const str = s.substr(i, j - i + 1); + if(str.length > 3 || +str > 255) break; + if(str.length > 1 && str[0] === "0") break; + path.push(str); + backtracking(j + 1); + path.pop() + } + } +}; +``` ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) From 03ff3ad0cb4359705ffc5ff08059c83c95fbda73 Mon Sep 17 00:00:00 2001 From: borninfreedom Date: Sat, 5 Jun 2021 19:07:12 +0800 Subject: [PATCH 14/30] =?UTF-8?q?=E7=BB=99=E5=85=B6=E4=BB=96=E5=87=A0?= =?UTF-8?q?=E9=81=93=E9=A2=98=E7=9B=AE=E6=B7=BB=E5=8A=A0=E4=BA=86python?= =?UTF-8?q?=E7=9A=84=E4=BB=A3=E7=A0=81?= 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 | 184 +++++++++++++++++++++- 1 file changed, 183 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 bfb78a43..c7fdf776 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 @@ -99,7 +99,7 @@ class Solution: while quene: in_list = [] - for i in range(len(quene)): + for _ in range(len(quene)): node = quene.pop(0) in_list.append(node.val) if node.left: @@ -185,6 +185,43 @@ public: } }; ``` +python代码： + +```python +# Definition for a binary tree node. +# class TreeNode: +# def __init__(self, val=0, left=None, right=None): +# self.val = val +# self.left = left +# self.right = right +class Solution: + def levelOrderBottom(self, root: TreeNode) -> List[List[int]]: + if not root: + return [] + quene = [root] + out_list = [] + + while quene: + 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) + + out_list.append(in_list) + + out_list.reverse() + return out_list + +# 执行用时：36 ms, 在所有 Python3 提交中击败了92.00%的用户 +# 内存消耗：15.2 MB, 在所有 Python3 提交中击败了63.76%的用户 +``` + + + javascript代码 ```javascript @@ -246,6 +283,50 @@ public: } }; ``` +python代码： + +```python +# Definition for a binary tree node. +# class TreeNode: +# def __init__(self, val=0, left=None, right=None): +# self.val = val +# self.left = left +# self.right = right +class Solution: + def rightSideView(self, root: TreeNode) -> List[int]: + if not root: + return [] + + # deque来自collections模块，不在力扣平台时，需要手动写入 + # 'from collections import deque' 导入 + # deque相比list的好处是，list的pop(0)是O(n)复杂度，deque的popleft()是O(1)复杂度 + + quene = deque([root]) + out_list = [] + + while quene: + # 每次都取最后一个node就可以了 + node = quene[-1] + out_list.append(node.val) + + # 执行这个遍历的目的是获取下一层所有的node + for _ in range(len(quene)): + node = quene.popleft() + if node.left: + quene.append(node.left) + if node.right: + quene.append(node.right) + + return out_list + +# 执行用时：36 ms, 在所有 Python3 提交中击败了89.47%的用户 +# 内存消耗：14.6 MB, 在所有 Python3 提交中击败了96.65%的用户 +``` + + + + + javascript代码: ```javascript @@ -309,6 +390,46 @@ public: ``` +python代码： + +```python +# Definition for a binary tree node. +# class TreeNode: +# def __init__(self, val=0, left=None, right=None): +# self.val = val +# self.left = left +# self.right = right +class Solution: + def averageOfLevels(self, root: TreeNode) -> List[float]: + if not root: + return [] + + quene = deque([root]) + out_list = [] + + while quene: + in_list = [] + + for _ in range(len(quene)): + node = quene.popleft() + in_list.append(node.val) + if node.left: + quene.append(node.left) + if node.right: + quene.append(node.right) + + out_list.append(in_list) + + out_list = map(lambda x: sum(x) / len(x), out_list) + + return out_list + +# 执行用时：56 ms, 在所有 Python3 提交中击败了81.48%的用户 +# 内存消耗：17 MB, 在所有 Python3 提交中击败了89.68%的用户 +``` + + + javascript代码： ```javascript @@ -385,7 +506,68 @@ public: }; ``` +python代码： + +```python +""" +# Definition for a Node. +class Node: + def __init__(self, val=None, children=None): + self.val = val + self.children = children +""" + +class Solution: + def levelOrder(self, root: 'Node') -> List[List[int]]: + if not root: + return [] + + quene = deque([root]) + out_list = [] + + while quene: + in_list = [] + + for _ in range(len(quene)): + node = quene.popleft() + in_list.append(node.val) + if node.children: + # 这个地方要用extend而不是append，我们看下面的例子： + # In [18]: alist=[] + # In [19]: alist.append([1,2,3]) + # In [20]: alist + # Out[20]: [[1, 2, 3]] + # In [21]: alist.extend([4,5,6]) + # In [22]: alist + # Out[22]: [[1, 2, 3], 4, 5, 6] + # 可以看到extend对要添加的list进行了一个解包操作 + # print(root.children)，可以得到children是一个包含 + # 孩子节点地址的list，我们使用for遍历quene的时候， + # 希望quene是一个单层list，所以要用extend + # 使用extend的情况，如果print(quene),结果是 + # deque([<__main__.Node object at 0x7f60763ae0a0>]) + # deque([<__main__.Node object at 0x7f607636e6d0>, <__main__.Node object at 0x7f607636e130>, <__main__.Node object at 0x7f607636e310>]) + # deque([<__main__.Node object at 0x7f607636e880>, <__main__.Node object at 0x7f607636ef10>]) + # 可以看到是单层list + # 如果使用append，print(quene)的结果是 + # deque([<__main__.Node object at 0x7f18907530a0>]) + # deque([[<__main__.Node object at 0x7f18907136d0>, <__main__.Node object at 0x7f1890713130>, <__main__.Node object at 0x7f1890713310>]]) + # 可以看到是两层list，这样for的遍历就会报错 + + quene.extend(node.children) + + out_list.append(in_list) + + return out_list + +# 执行用时：60 ms, 在所有 Python3 提交中击败了76.99%的用户 +# 内存消耗：16.5 MB, 在所有 Python3 提交中击败了89.19%的用户 +``` + + + JavaScript代码： + ```JavaScript var levelOrder = function(root) { //每一层可能有2个以上,所以不再使用node.left node.right From 546865ce4c18c00589dad748e9f8c7eaa29ede80 Mon Sep 17 00:00:00 2001 From: LiangDazhu <42199191+LiangDazhu@users.noreply.github.com> Date: Sun, 6 Jun 2021 00:44:21 +0800 Subject: [PATCH 15/30] =?UTF-8?q?Update=200474.=E4=B8=80=E5=92=8C=E9=9B=B6?= =?UTF-8?q?.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Added python version code --- problems/0474.一和零.md | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/problems/0474.一和零.md b/problems/0474.一和零.md index e158ca63..a098b9ef 100644 --- a/problems/0474.一和零.md +++ b/problems/0474.一和零.md @@ -190,7 +190,18 @@ class Solution { ``` Python： - +```python +class Solution: + def findMaxForm(self, strs: List[str], m: int, n: int) -> int: + dp = [[0] * (n + 1) for _ in range(m + 1)] + for str in strs: + oneNum = str.count('1') + zeroNum = str.count('0') + for i in range(m, zeroNum - 1, -1): + for j in range(n, oneNum - 1, -1): + dp[i][j] = max(dp[i][j], dp[i - zeroNum][j - oneNum] + 1) + return dp[m][n] +``` Go： From d25bdef4a515064542c064abc073f09e29ce104c Mon Sep 17 00:00:00 2001 From: Yang Date: Sat, 5 Jun 2021 20:14:18 -0400 Subject: [PATCH 16/30] =?UTF-8?q?Update=200377.=E7=BB=84=E5=90=88=E6=80=BB?= =?UTF-8?q?=E5=92=8C=E2=85=A3.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Separate Java and Python code --- problems/0377.组合总和Ⅳ.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0377.组合总和Ⅳ.md b/problems/0377.组合总和Ⅳ.md index 6813f13c..c6dc3d42 100644 --- a/problems/0377.组合总和Ⅳ.md +++ b/problems/0377.组合总和Ⅳ.md @@ -163,7 +163,7 @@ class Solution { return dp[target]; } } - +``` Python： From ea6dcc9d8f5962e13bdd9f8034f244bfec450c42 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Sat, 5 Jun 2021 17:33:44 -0700 Subject: [PATCH 17/30] =?UTF-8?q?Update=200222.=E5=AE=8C=E5=85=A8=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=A0=91=E7=9A=84=E8=8A=82=E7=82=B9=E4=B8=AA=E6=95=B0?= =?UTF-8?q?.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0222.完全二叉树的节点个数.md | 65 +++++++++++++++++++ 1 file changed, 65 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 2e2fed99..91e24247 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 @@ -240,6 +240,71 @@ class Solution { Python： +> 递归法： +```python +class Solution: + def countNodes(self, root: TreeNode) -> int: + return self.getNodesNum(root) + + def getNodesNum(self, cur): + if not cur: + return 0 + leftNum = self.getNodesNum(cur.left) #左 + rightNum = self.getNodesNum(cur.right) #右 + treeNum = leftNum + rightNum + 1 #中 + return treeNum +``` + +> 递归法：精简版 +```python +class Solution: + def countNodes(self, root: TreeNode) -> int: + if not root: + return 0 + return 1 + self.countNodes(root.left) + self.countNodes(root.right) +``` + +> 迭代法： +```python +import collections +class Solution: + def countNodes(self, root: TreeNode) -> int: + queue = collections.deque() + if root: + queue.append(root) + result = 0 + while queue: + size = len(queue) + for i in range(size): + node = queue.popleft() + result += 1 #记录节点数量 + if node.left: + queue.append(node.left) + if node.right: + queue.append(node.right) + return result +``` + +> 完全二叉树 +```python +class Solution: + def countNodes(self, root: TreeNode) -> int: + if not root: + return 0 + left = root.left + right = root.right + leftHeight = 0 #这里初始为0是有目的的，为了下面求指数方便 + rightHeight = 0 + while left: #求左子树深度 + left = left.left + leftHeight += 1 + while right: #求右子树深度 + right = right.right + rightHeight += 1 + if leftHeight == rightHeight: + return (2 << leftHeight) - 1 #注意(2<<1) 相当于2^2，所以leftHeight初始为0 + return self.countNodes(root.left) + self.countNodes(root.right) + 1 +``` Go： From 6efc66e17597da3038966c690bb75dd4f0e61ad0 Mon Sep 17 00:00:00 2001 From: Baturu <45113401+z80160280@users.noreply.github.com> Date: Sat, 5 Jun 2021 18:13:20 -0700 Subject: [PATCH 18/30] =?UTF-8?q?Update=200110.=E5=B9=B3=E8=A1=A1=E4=BA=8C?= =?UTF-8?q?=E5=8F=89=E6=A0=91.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0110.平衡二叉树.md | 56 ++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/problems/0110.平衡二叉树.md b/problems/0110.平衡二叉树.md index 1cd54849..b9d01503 100644 --- a/problems/0110.平衡二叉树.md +++ b/problems/0110.平衡二叉树.md @@ -498,6 +498,62 @@ class Solution { Python： +> 递归法： +```python +class Solution: + def isBalanced(self, root: TreeNode) -> bool: + return True if self.getDepth(root) != -1 else False + + #返回以该节点为根节点的二叉树的高度，如果不是二叉搜索树了则返回-1 + def getDepth(self, node): + if not node: + return 0 + leftDepth = self.getDepth(node.left) + if leftDepth == -1: return -1 #说明左子树已经不是二叉平衡树 + rightDepth = self.getDepth(node.right) + if rightDepth == -1: return -1 #说明右子树已经不是二叉平衡树 + return -1 if abs(leftDepth - rightDepth)>1 else 1 + max(leftDepth, rightDepth) +``` + +> 迭代法： +```python +class Solution: + def isBalanced(self, root: TreeNode) -> bool: + st = [] + if not root: + return True + st.append(root) + while st: + node = st.pop() #中 + if abs(self.getDepth(node.left) - self.getDepth(node.right)) > 1: + return False + if node.right: + st.append(node.right) #右（空节点不入栈） + if node.left: + st.append(node.left) #左（空节点不入栈） + return True + + def getDepth(self, cur): + st = [] + if cur: + st.append(cur) + depth = 0 + result = 0 + while st: + node = st.pop() + if node: + st.append(node) #中 + st.append(None) + depth += 1 + if node.right: st.append(node.right) #右 + if node.left: st.append(node.left) #左 + else: + node = st.pop() + depth -= 1 + result = max(result, depth) + return result +``` + Go： ```Go From d68e8922ceea44b9b066025cbbe61e5762d61216 Mon Sep 17 00:00:00 2001 From: Jack Choi <648074155@qq.com> Date: Sun, 6 Jun 2021 11:05:52 +0800 Subject: [PATCH 19/30] =?UTF-8?q?Update=200027.=E7=A7=BB=E9=99=A4=E5=85=83?= =?UTF-8?q?=E7=B4=A0.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0027.移除元素.md | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md index f0f61d06..f1187db7 100644 --- a/problems/0027.移除元素.md +++ b/problems/0027.移除元素.md @@ -199,7 +199,23 @@ def remove_element(nums, val) i end ``` - +Rust: +```rust +pub fn remove_element(nums: &mut Vec, val: i32) -> &mut Vec { + let mut start: usize = 0; + while start < nums.len() { + if nums[start] == val { + nums.remove(start); + } + start += 1; + } + nums +} +fn main() { + let mut nums = vec![5,1,3,5,2,3,4,1]; + println!("{:?}",remove_element(&mut nums, 5)); +} +``` ----------------------- * 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 4dda01ba256a0584fbe20a88ceb73335eb27269c Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Sun, 6 Jun 2021 11:44:12 +0800 Subject: [PATCH 20/30] =?UTF-8?q?Update=200474.=E4=B8=80=E5=92=8C=E9=9B=B6?= =?UTF-8?q?.md=20=E6=B7=BB=E5=8A=A0=E4=B8=80=E5=92=8C=E9=9B=B6=20python3?= =?UTF-8?q?=20=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 | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/problems/0474.一和零.md b/problems/0474.一和零.md index e158ca63..1e0dc794 100644 --- a/problems/0474.一和零.md +++ b/problems/0474.一和零.md @@ -191,6 +191,31 @@ class Solution { Python： +```python3 +class Solution: + def countBinary(self, s: str) -> (int, int): + zeros, ones = 0, 0 + for c in s: + if c == '0': + zeros += 1 + else: + ones += 1 + return zeros, ones + + def findMaxForm(self, strs: List[str], m: int, n: int) -> int: + dp = [[0]*(n + 1) for _ in range(m + 1)] # 默认初始化0 + # 遍历物品 + for i in range(len(strs)): + # num_zeros = strs[i].count('0') + # num_ones = strs[i].count('1') + num_zeros, num_ones = self.countBinary(strs[i]) + # 遍历背包容量且从后向前遍历！ + for j in range(m, num_zeros - 1, -1): + for i in range(n, num_ones - 1, -1): + dp[j][i] = max(dp[j - num_zeros][i - num_ones] + 1, dp[j][i]) + return dp[m][n] +``` + Go： From 9c0fe0ff494aa14ba28816b7f5fec6e6a7b61687 Mon Sep 17 00:00:00 2001 From: haofeng <852172305@qq.com> Date: Sun, 6 Jun 2021 15:55:35 +0800 Subject: [PATCH 21/30] =?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 --- .../背包问题理论基础完全背包.md | 38 ++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) 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 02785ad7..9997dff3 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 @@ -179,9 +179,45 @@ int main() { Java： - Python： +```python3 +# 先遍历物品，再遍历背包 +def test_complete_pack1(): + weight = [1, 3, 4] + value = [15, 20, 30] + bag_weight = 4 + + dp = [0]*(bag_weight + 1) + + for i in range(len(weight)): + for j in range(weight[i], bag_weight + 1): + dp[j] = max(dp[j], dp[j - weight[i]] + value[i]) + + print(dp[bag_weight]) + +# 先遍历背包，再遍历物品 +def test_complete_pack2(): + weight = [1, 3, 4] + value = [15, 20, 30] + bag_weight = 4 + + dp = [0]*(bag_weight + 1) + + for j in range(bag_weight + 1): + for i in range(len(weight)): + if j >= weight[i]: dp[j] = max(dp[j], dp[j - weight[i]] + value[i]) + + print(dp[bag_weight]) + + +if __name__ == '__main__': + test_complete_pack1() + test_complete_pack2() +``` + + + Go： 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 22/30] =?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 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 23/30] =?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 24/30] =?UTF-8?q?Update=200198.=E6=89=93=E5=AE=B6=E5=8A=AB?= =?UTF-8?q?=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 25/30] =?UTF-8?q?Update=200337.=E6=89=93=E5=AE=B6=E5=8A=AB?= =?UTF-8?q?=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 26/30] =?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 27/30] =?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 28/30] =?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 29/30] =?UTF-8?q?Update=200530.=E4=BA=8C=E5=8F=89=E6=90=9C?= =?UTF-8?q?=E7=B4=A2=E6=A0=91=E7=9A=84=E6=9C=80=E5=B0=8F=E7=BB=9D=E5=AF=B9?= =?UTF-8?q?=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 30/30] =?UTF-8?q?=E6=B7=BB=E5=8A=A00474.=E4=B8=80=E5=92=8C?= =?UTF-8?q?=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 +} +```