From ef44e750cec20980095e63db3c090c8df48f620c Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Mon, 11 Apr 2022 20:34:32 +0100 Subject: [PATCH 01/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200376.=E6=91=86?= =?UTF-8?q?=E5=8A=A8=E5=BA=8F=E5=88=97.md=20C=E8=AF=AD=E8=A8=80?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0376.摆动序列.md | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/problems/0376.摆动序列.md b/problems/0376.摆动序列.md index 5076c9ad..6bd2277f 100644 --- a/problems/0376.摆动序列.md +++ b/problems/0376.摆动序列.md @@ -298,5 +298,32 @@ var wiggleMaxLength = function(nums) { }; ``` +### C +**贪心** +```c +int wiggleMaxLength(int* nums, int numsSize){ + if(numsSize <= 1) + return numsSize; + + int length = 1; + int preDiff , curDiff; + preDiff = curDiff = 0; + for(int i = 0; i < numsSize - 1; ++i) { + // 计算当前i元素与i+1元素差值 + curDiff = nums[i+1] - nums[i]; + + // 若preDiff与curDiff符号不符，则子序列长度+1。更新preDiff的符号 + // 若preDiff与curDiff符号一致，当前i元素为连续升序/连续降序子序列的中间元素。不被记录入长度 + // 注：当preDiff为0时，curDiff为正或为负都属于符号不同 + if((curDiff > 0 && preDiff <= 0) || (preDiff >= 0 && curDiff < 0)) { + preDiff = curDiff; + length++; + } + } + + return length; +} +``` + -----------------------
From 54d0d9d1c1a579e0a8750f1be864ad78b8d13c45 Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Tue, 12 Apr 2022 10:43:46 +0100 Subject: [PATCH 02/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200053.=E6=9C=80?= =?UTF-8?q?=E5=A4=A7=E5=AD=90=E6=95=B0=E7=BB=84=E5=92=8C.md=20C=E8=AF=AD?= =?UTF-8?q?=E8=A8=80=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0053.最大子序和.md | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/problems/0053.最大子序和.md b/problems/0053.最大子序和.md index 3d11c91e..9af02edf 100644 --- a/problems/0053.最大子序和.md +++ b/problems/0053.最大子序和.md @@ -230,6 +230,24 @@ var maxSubArray = function(nums) { }; ``` +### C: +```c +int maxSubArray(int* nums, int numsSize){ + int maxVal = INT_MIN; + int subArrSum = 0; + + int i; + for(i = 0; i < numsSize; ++i) { + subArrSum += nums[i]; + // 若当前局部和大于之前的最大结果，对结果进行更新 + maxVal = subArrSum > maxVal ? subArrSum : maxVal; + // 若当前局部和为负，对结果无益。则从nums[i+1]开始应重新计算。 + subArrSum = subArrSum < 0 ? 0 : subArrSum; + } + + return maxVal; +} +``` ----------------------- From af724ef6d5ed95c4ba545a932f8257b487648aec Mon Sep 17 00:00:00 2001 From: xuerbujia <83055661+xuerbujia@users.noreply.github.com> Date: Tue, 12 Apr 2022 17:45:50 +0800 Subject: [PATCH 03/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880143.=E9=87=8D?= =?UTF-8?q?=E6=8E=92=E9=93=BE=E8=A1=A8.md=EF=BC=89=EF=BC=9A=E5=A2=9E?= =?UTF-8?q?=E5=8A=A0go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0143.重排链表.md | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/problems/0143.重排链表.md b/problems/0143.重排链表.md index 00622623..790bcb48 100644 --- a/problems/0143.重排链表.md +++ b/problems/0143.重排链表.md @@ -336,7 +336,33 @@ class Solution: return pre ``` ### Go - +```go +# 方法三 分割链表 +func reorderList(head *ListNode) { + var slow=head + var fast=head + for fast!=nil&&fast.Next!=nil{ + slow=slow.Next + fast=fast.Next.Next + } //双指针将链表分为左右两部分 + var right =new(ListNode) + for slow!=nil{ + temp:=slow.Next + slow.Next=right.Next + right.Next=slow + slow=temp + } //翻转链表右半部分 + right=right.Next //right为反转后得右半部分 + h:=head + for right.Next!=nil{ + temp:=right.Next + right.Next=h.Next + h.Next=right + h=h.Next.Next + right=temp + } //将左右两部分重新组合 +} +``` ### JavaScript ```javascript From dd63a865717b0a439cc2ce2b5abab0a55d18d7de Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Tue, 12 Apr 2022 11:01:53 +0100 Subject: [PATCH 04/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200053.=E6=9C=80?= =?UTF-8?q?=E5=A4=A7=E5=AD=90=E6=95=B0=E7=BB=84=E5=92=8C.md=20C=E8=AF=AD?= =?UTF-8?q?=E8=A8=80=E5=8A=A8=E6=80=81=E8=A7=84=E5=88=92=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0053.最大子序和.md | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/problems/0053.最大子序和.md b/problems/0053.最大子序和.md index 9af02edf..3d4459a3 100644 --- a/problems/0053.最大子序和.md +++ b/problems/0053.最大子序和.md @@ -231,6 +231,7 @@ var maxSubArray = function(nums) { ``` ### C: +贪心： ```c int maxSubArray(int* nums, int numsSize){ int maxVal = INT_MIN; @@ -249,6 +250,39 @@ int maxSubArray(int* nums, int numsSize){ } ``` +动态规划： +```c +/** + * 解题思路：动态规划： + * 1. dp数组：dp[i]表示从0到i的子序列中最大序列和的值 + * 2. 递推公式：dp[i] = max(dp[i-1] + nums[i], nums[i]) + 若dp[i-1]<0，对最后结果无益。dp[i]则为nums[i]。 + * 3. dp数组初始化：dp[0]的最大子数组和为nums[0] + * 4. 推导顺序：从前往后遍历 + */ + +#define max(a, b) (((a) > (b)) ? (a) : (b)) + +int maxSubArray(int* nums, int numsSize){ + int dp[numsSize]; + // dp[0]最大子数组和为nums[0] + dp[0] = nums[0]; + // 若numsSize为1，应直接返回nums[0] + int subArrSum = nums[0]; + + int i; + for(i = 1; i < numsSize; ++i) { + dp[i] = max(dp[i - 1] + nums[i], nums[i]); + + // 若dp[i]大于之前记录的最大值，进行更新 + if(dp[i] > subArrSum) + subArrSum = dp[i]; + } + + return subArrSum; +} +``` + -----------------------
From 1b935259a6c83beab9f730059da4bec509bb1f61 Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Tue, 12 Apr 2022 21:01:23 +0100 Subject: [PATCH 05/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200122.=E4=B9=B0?= =?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.md=20C=E8=AF=AD=E8=A8=80=E5=8A=A8=E6=80=81=E8=A7=84=E5=88=92?= =?UTF-8?q?=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0122.买卖股票的最佳时机II.md | 24 ++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/problems/0122.买卖股票的最佳时机II.md b/problems/0122.买卖股票的最佳时机II.md index 83b852c6..1b84f728 100644 --- a/problems/0122.买卖股票的最佳时机II.md +++ b/problems/0122.买卖股票的最佳时机II.md @@ -269,7 +269,7 @@ const maxProfit = (prices) => { ``` C: - +贪心： ```c int maxProfit(int* prices, int pricesSize){ int result = 0; @@ -284,5 +284,27 @@ int maxProfit(int* prices, int pricesSize){ } ``` +动态规划： +```c +#define max(a, b) (((a) > (b)) ? (a) : (b)) + +int maxProfit(int* prices, int pricesSize){ + int dp[pricesSize][2]; + dp[0][0] = 0 - prices[0]; + dp[0][1] = 0; + + int i; + for(i = 1; i < pricesSize; ++i) { + // dp[i][0]为i-1天持股的钱数/在第i天用i-1天的钱买入的最大值。 + // 若i-1天持股，且第i天买入股票比i-1天持股时更亏，说明应在i-1天时持股 + dp[i][0] = max(dp[i-1][0], dp[i-1][1] - prices[i]); + //dp[i][1]为i-1天不持股钱数/在第i天卖出所持股票dp[i-1][0] + prices[i]的最大值 + dp[i][1] = max(dp[i-1][1], dp[i-1][0] + prices[i]); + } + // 返回在最后一天不持股时的钱数（将股票卖出后钱最大化） + return dp[pricesSize - 1][1]; +} +``` + -----------------------
From e1abedc13ad4d5f744ecc27fa9931aa24508364b Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Wed, 13 Apr 2022 09:41:50 +0100 Subject: [PATCH 06/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200055.=E8=B7=B3?= =?UTF-8?q?=E8=B7=83=E6=B8=B8=E6=88=8F.md=20C=E8=AF=AD=E8=A8=80=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0055.跳跃游戏.md | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/problems/0055.跳跃游戏.md b/problems/0055.跳跃游戏.md index c0890f75..4ba0c03b 100644 --- a/problems/0055.跳跃游戏.md +++ b/problems/0055.跳跃游戏.md @@ -154,6 +154,28 @@ var canJump = function(nums) { }; ``` +### C +```c +#define max(a, b) (((a) > (b)) ? (a) : (b)) + +bool canJump(int* nums, int numsSize){ + int cover = 0; + + int i; + // 只可能获取cover范围中的步数，所以i<=cover + for(i = 0; i <= cover; ++i) { + // 更新cover为从i出发能到达的最大值/cover的值中较大值 + cover = max(i + nums[i], cover); + + // 若更新后cover可以到达最后的元素，返回true + if(cover >= numsSize - 1) + return true; + } + + return false; +} +``` + -----------------------
From b73a7da7585b03b42ab51515f5463259ac2e0631 Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Fri, 15 Apr 2022 18:25:41 +0100 Subject: [PATCH 07/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=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.md=20C=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...1005.K次取反后最大化的数组和.md | 39 +++++++++++++++++++ 1 file changed, 39 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 45f186e2..0d122d91 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 @@ -211,5 +211,44 @@ var largestSumAfterKNegations = function(nums, k) { }; ``` +### C +```c +#define abs(a) (((a) > 0) ? (a) : (-(a))) + +// 对数组求和 +int sum(int *nums, int numsSize) { + int sum = 0; + + int i; + for(i = 0; i < numsSize; ++i) { + sum += nums[i]; + } + return sum; +} + +int cmp(const void* v1, const void* v2) { + return abs(*(int*)v2) - abs(*(int*)v1); +} + +int largestSumAfterKNegations(int* nums, int numsSize, int k){ + qsort(nums, numsSize, sizeof(int), cmp); + + int i; + for(i = 0; i < numsSize; ++i) { + // 遍历数组，若当前元素<0则将当前元素转变，k-- + if(nums[i] < 0 && k > 0) { + nums[i] *= -1; + --k; + } + } + + // 若遍历完数组后k还有剩余（此时所有元素应均为正），则将绝对值最小的元素nums[numsSize - 1]变为负 + if(k % 2 == 1) + nums[numsSize - 1] *= -1; + + return sum(nums, numsSize); +} +``` + -----------------------
From 7c26aba0e1d9ba38a631eb5dbae8577890deb2d2 Mon Sep 17 00:00:00 2001 From: Falldio <1031249495@qq.com> Date: Sun, 17 Apr 2022 11:59:30 +0800 Subject: [PATCH 08/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880209.=E9=95=BF?= =?UTF-8?q?=E5=BA=A6=E6=9C=80=E5=B0=8F=E7=9A=84=E5=AD=90=E6=95=B0=E7=BB=84?= =?UTF-8?q?.md=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0Kotlin=E7=89=88=E6=9C=AC?= 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 | 31 +++++++++++++++++++---- 1 file changed, 26 insertions(+), 5 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 82a11381..fd72cf1b 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 @@ -198,7 +198,7 @@ JavaScript: var minSubArrayLen = function(target, nums) { // 长度计算一次 const len = nums.length; - let l = r = sum = 0, + let l = r = sum = 0, res = len + 1; // 子数组最大不会超过自身 while(r < len) { sum += nums[r++]; @@ -260,12 +260,12 @@ Rust: ```rust impl Solution { - pub fn min_sub_array_len(target: i32, nums: Vec) -> i32 { + pub fn min_sub_array_len(target: i32, nums: Vec) -> i32 { let (mut result, mut subLength): (i32, i32) = (i32::MAX, 0); let (mut sum, mut i) = (0, 0); - + for (pos, val) in nums.iter().enumerate() { - sum += val; + sum += val; while sum >= target { subLength = (pos - i + 1) as i32; if result > subLength { @@ -364,7 +364,7 @@ int minSubArrayLen(int target, int* nums, int numsSize){ int minLength = INT_MAX; int sum = 0; - int left = 0, right = 0; + int left = 0, right = 0; //右边界向右扩展 for(; right < numsSize; ++right) { sum += nums[right]; @@ -380,5 +380,26 @@ int minSubArrayLen(int target, int* nums, int numsSize){ } ``` +Kotlin: +```kotlin +class Solution { + fun minSubArrayLen(target: Int, nums: IntArray): Int { + var start = 0 + var end = 0 + var ret = Int.MAX_VALUE + var count = 0 + while (end < nums.size) { + count += nums[end] + while (count >= target) { + ret = if (ret > (end - start + 1)) end - start + 1 else ret + count -= nums[start++] + } + end++ + } + return if (ret == Int.MAX_VALUE) 0 else ret + } +} +``` + -----------------------
From 0375a5b147c40a449c04ef7f988dfcb2d93b9e01 Mon Sep 17 00:00:00 2001 From: Guacker <92098421+Guacker@users.noreply.github.com> Date: Sun, 17 Apr 2022 17:19:00 +0800 Subject: [PATCH 09/10] =?UTF-8?q?Update=20=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=E7=9A=84=E9=80=92=E5=BD=92=E9=81=8D=E5=8E=86.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 修改了c语言实现的先序遍历函数名 和内部调用时用的函数名 及在preorderTraversal中的调用先序遍历操作的函数名 --- problems/二叉树的递归遍历.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 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 35d19d7b..612f2394 100644 --- a/problems/二叉树的递归遍历.md +++ b/problems/二叉树的递归遍历.md @@ -371,18 +371,18 @@ C: ```c //前序遍历： -void preOrderTraversal(struct TreeNode* root, int* ret, int* returnSize) { +void preOrder(struct TreeNode* root, int* ret, int* returnSize) { if(root == NULL) return; ret[(*returnSize)++] = root->val; - preOrderTraverse(root->left, ret, returnSize); - preOrderTraverse(root->right, ret, returnSize); + preOrder(root->left, ret, returnSize); + preOrder(root->right, ret, returnSize); } int* preorderTraversal(struct TreeNode* root, int* returnSize){ int* ret = (int*)malloc(sizeof(int) * 100); *returnSize = 0; - preOrderTraversal(root, ret, returnSize); + preOrder(root, ret, returnSize); return ret; } From 84f41f6685e744b138890cf7143ed3069a02a78e Mon Sep 17 00:00:00 2001 From: Guanzhong Pan Date: Tue, 19 Apr 2022 17:00:17 +0100 Subject: [PATCH 10/10] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200135.=E5=88=86?= =?UTF-8?q?=E5=8F=91=E7=B3=96=E6=9E=9C.md=20C=E8=AF=AD=E8=A8=80=E8=A7=A3?= =?UTF-8?q?=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0135.分发糖果.md | 41 +++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/problems/0135.分发糖果.md b/problems/0135.分发糖果.md index ccdabc16..27071aee 100644 --- a/problems/0135.分发糖果.md +++ b/problems/0135.分发糖果.md @@ -238,6 +238,47 @@ var candy = function(ratings) { }; ``` +### C +```c +#define max(a, b) (((a) > (b)) ? (a) : (b)) + +int *initCandyArr(int size) { + int *candyArr = (int*)malloc(sizeof(int) * size); + + int i; + for(i = 0; i < size; ++i) + candyArr[i] = 1; + + return candyArr; +} + +int candy(int* ratings, int ratingsSize){ + // 初始化数组，每个小孩开始至少有一颗糖 + int *candyArr = initCandyArr(ratingsSize); + + int i; + // 先判断右边是否比左边评分高。若是，右边孩子的糖果为左边孩子+1（candyArr[i] = candyArr[i - 1] + 1) + for(i = 1; i < ratingsSize; ++i) { + if(ratings[i] > ratings[i - 1]) + candyArr[i] = candyArr[i - 1] + 1; + } + + // 再判断左边评分是否比右边高。 + // 若是，左边孩子糖果为右边孩子糖果+1/自己所持糖果最大值。（若糖果已经比右孩子+1多，则不需要更多糖果） + // 举例：ratings为[1, 2, 3, 1]。此时评分为3的孩子在判断右边比左边大后为3，虽然它比最末尾的1(ratings[3])大，但是candyArr[3]为1。所以不必更新candyArr[2] + for(i = ratingsSize - 2; i >= 0; --i) { + if(ratings[i] > ratings[i + 1]) + candyArr[i] = max(candyArr[i], candyArr[i + 1] + 1); + } + + // 求出糖果之和 + int result = 0; + for(i = 0; i < ratingsSize; ++i) { + result += candyArr[i]; + } + return result; +} +``` -----------------------