Merge branch 'master' of github.com:youngyangyang04/leetcode-master

problems/0001.两数之和.md

@@ -133,6 +133,7 @@ public:
 ### Java：
 
 ```java
+//使用哈希表
 public int[] twoSum(int[] nums, int target) {
     int[] res = new int[2];
     if(nums == null || nums.length == 0){
@@ -151,6 +152,43 @@ public int[] twoSum(int[] nums, int target) {
     return res;
 }
 ```
+```java
+//使用双指针
+public int[] twoSum(int[] nums, int target) {
+    int m=0,n=0,k,board=0;
+    int[] res=new int[2];
+    int[] tmp1=new int[nums.length];
+    //备份原本下标的nums数组
+    System.arraycopy(nums,0,tmp1,0,nums.length);
+    //将nums排序
+    Arrays.sort(nums);
+    //双指针
+    for(int i=0,j=nums.length-1;i<j;){
+        if(nums[i]+nums[j]<target)
+            i++;
+        else if(nums[i]+nums[j]>target)
+            j--;
+        else if(nums[i]+nums[j]==target){
+            m=i;
+            n=j;
+            break;
+        }
+    }
+    //找到nums[m]在tmp1数组中的下标
+    for(k=0;k<nums.length;k++){
+        if(tmp1[k]==nums[m]){
+            res[0]=k;
+            break;
+        }
+    }
+    //找到nums[n]在tmp1数组中的下标
+    for(int i=0;i<nums.length;i++){
+        if(tmp1[i]==nums[n]&&i!=k)
+            res[1]=i;
+    }
+    return res;
+}
+```
 
 ### Python：
 （版本一） 使用字典

problems/0005.最长回文子串.md

@@ -618,7 +618,7 @@ char * longestPalindrome(char * s){
 ### C#：
 
 動態規則：
-```c#
+```csharp
 public class Solution {
     
     public string LongestPalindrome(string s) {
@@ -648,7 +648,7 @@ public class Solution {
 ```
 
 雙指針：
-```C#
+```csharp
 public class Solution {
     int maxlenth = 0;
     int left = 0;

problems/0015.三数之和.md

@@ -256,7 +256,7 @@ while (right > left) {
 ## 其他语言版本
 
 ### Java：
-
+（版本一） 双指针
 ```Java
 class Solution {
     public List<List<Integer>> threeSum(int[] nums) {
@@ -297,7 +297,43 @@ class Solution {
     }
 }
 ```
+（版本二） 使用哈希集合
+```Java
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+	List<List<Integer>> result = new ArrayList<>();
+	Arrays.sort(nums);
 
+	for (int i = 0; i < nums.length; i++) {
+		// 如果第一个元素大于零，不可能凑成三元组
+		if (nums[i] > 0) {
+			return result;
+		}
+		// 三元组元素a去重
+		if (i > 0 && nums[i] == nums[i - 1]) {
+			continue;
+		}
+
+		HashSet<Integer> set = new HashSet<>();
+		for (int j = i + 1; j < nums.length; j++) {
+			// 三元组元素b去重
+			if (j > i + 2 && nums[j] == nums[j - 1] && nums[j - 1] == nums[j - 2]) {
+				continue;
+			}
+
+			int c = -nums[i] - nums[j];
+			if (set.contains(c)) {
+				result.add(Arrays.asList(nums[i], nums[j], c));
+				set.remove(c); // 三元组元素c去重
+			} else {
+				set.add(nums[j]);
+			}
+		}
+	}
+	return result;
+    }
+}
+```
 ### Python：
 （版本一） 双指针
 

problems/0017.电话号码的字母组合.md

@@ -733,7 +733,7 @@ def backtracking(result, letter_map, digits, path, index)
 end
 ```
 ### C#
-```C#
+```csharp
 public class Solution
 {
     public IList<string> res = new List<string>();

problems/0019.删除链表的倒数第N个节点.md

@@ -82,7 +82,7 @@ public:
         
         // ListNode *tmp = slow->next;  C++释放内存的逻辑
         // slow->next = tmp->next;
-        // delete nth;
+        // delete tmp;
         
         return dummyHead->next;
     }

problems/0024.两两交换链表中的节点.md

@@ -462,7 +462,7 @@ impl Solution {
 ```
 
 ### C#
-```C#
+```csharp
 // 虚拟头结点
 public ListNode SwapPairs(ListNode head)
 {

problems/0028.实现strStr.md

@@ -425,8 +425,8 @@ public:
         if (needle.size() == 0) {
             return 0;
         }
-        int next[needle.size()];
+		vector<int> next(needle.size());
-        getNext(next, needle);
+		getNext(&next[0], needle);
         int j = -1; // // 因为next数组里记录的起始位置为-1
         for (int i = 0; i < haystack.size(); i++) { // 注意i就从0开始
             while(j >= 0 && haystack[i] != needle[j + 1]) { // 不匹配
@@ -524,8 +524,8 @@ public:
         if (needle.size() == 0) {
             return 0;
         }
-        int next[needle.size()];
+        vector<int> next(needle.size());
-        getNext(next, needle);
+        getNext(&next[0], needle);
         int j = 0;
         for (int i = 0; i < haystack.size(); i++) {
             while(j > 0 && haystack[i] != needle[j]) {
@@ -1359,7 +1359,7 @@ impl Solution {
 ```
 
 >前缀表统一不减一
-```C#
+```csharp
 public int StrStr(string haystack, string needle)
 {
     if (string.IsNullOrEmpty(needle))
@@ -1428,4 +1428,3 @@ public int[] GetNext(string needle)
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0034.在排序数组中查找元素的第一个和最后一个位置.md

@@ -331,7 +331,7 @@ class Solution {
 
 ### C#
 
-```c#
+```csharp
 public int[] SearchRange(int[] nums, int target) {
 
 	var leftBorder = GetLeftBorder(nums, target);

problems/0045.跳跃游戏II.md

@@ -285,6 +285,34 @@ class Solution:
 
 ### Go
 
+
+```go
+/**
+ * @date: 2024 Jan 06
+ * @time: 13:44
+ * @author: Chris
+**/
+// 贪心算法优化版
+
+// 记录步骤规则：每超过上一次可达最大范围，需要跳跃一次，次数+1
+// 记录位置：i == lastDistance + 1
+func jump(nums []int) int {
+	// 根据题目规则，初始位置为nums[0]
+	lastDistance := 0 // 上一次覆盖范围
+	curDistance := 0  // 当前覆盖范围（可达最大范围）
+	minStep := 0      // 记录最少跳跃次数
+
+	for i := 0; i < len(nums); i++ {
+		if i == lastDistance+1 { // 在上一次可达范围+1的位置，记录步骤
+			minStep++                  // 跳跃次数+1
+			lastDistance = curDistance // 记录时才可以更新
+		}
+		curDistance = max(nums[i]+i, curDistance) // 更新当前可达的最大范围
+	}
+	return minStep
+}
+```
+
 ```go
 // 贪心版本一
 func jump(nums []int) int {
@@ -464,7 +492,34 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int jump(int* nums, int numsSize) {
+    if(numsSize == 1){
+        return 0;
+    }
+    int count = 0;
+    // 记录当前能走的最远距离
+    int curDistance = 0;
+    // 记录下一步能走的最远距离
+    int nextDistance = 0;
+    for(int i = 0; i < numsSize; i++){
+        nextDistance = max(i + nums[i], nextDistance);
+        // 下标到了当前的最大距离
+        if(i == nextDistance){
+            count++;
+            curDistance = nextDistance;
+        }
+    }
+    return count;
+}
+```
+
 ### C#
+
 ```csharp
 // 版本二
 public class Solution
@@ -490,3 +545,4 @@ public class Solution
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0053.最大子序和.md

@@ -230,7 +230,25 @@ class Solution:
 
 ```
 ### Go
+贪心法
+```go
+func maxSubArray(nums []int) int {
+    max := nums[0]
+    count := 0
 
+    for i := 0; i < len(nums); i++{
+        count += nums[i]
+        if count > max{
+            max = count
+        }
+        if count < 0 {
+            count = 0
+        }
+    } 
+    return max
+}
+```
+动态规划
 ```go
 func maxSubArray(nums []int) int {
     maxSum := nums[0]

problems/0054.螺旋矩阵.md

@@ -306,6 +306,47 @@ class Solution(object):
         return result
 ```
 
+版本二：定义四个边界
+```python
+class Solution(object):
+    def spiralOrder(self, matrix):
+        """
+        :type matrix: List[List[int]]
+        :rtype: List[int]
+            """
+        if not matrix:
+            return []
+
+        rows = len(matrix)
+        cols = len(matrix[0])
+        top, bottom, left, right = 0, rows - 1, 0, cols - 1
+        print_list = []
+
+        while top <= bottom and left <= right:
+            # 从左到右
+            for i in range(left, right + 1):
+                print_list.append(matrix[top][i])
+            top += 1
+
+            # 从上到下
+            for i in range(top, bottom + 1):
+                print_list.append(matrix[i][right])
+            right -= 1
+
+            # 从右到左
+            if top <= bottom:
+                for i in range(right, left - 1, -1):
+                    print_list.append(matrix[bottom][i])
+                bottom -= 1
+
+            # 从下到上
+            if left <= right:
+                for i in range(bottom, top - 1, -1):
+                    print_list.append(matrix[i][left])
+                left += 1
+
+        return print_list
+```
 
 
 <p align="center">

problems/0056.合并区间.md

@@ -336,9 +336,76 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+// 根据左边界进行排序
+int cmp(const void * var1, const void * var2){
+    int *v1 = *(int **) var1;
+    int *v2 = *(int **) var2;
+    return v1[0] - v2[0];
+}
+
+int** merge(int** intervals, int intervalsSize, int* intervalsColSize, int* returnSize, int** returnColumnSizes) {
+    int ** result = malloc(sizeof (int *) * intervalsSize);
+    * returnColumnSizes = malloc(sizeof (int ) * intervalsSize);
+    for(int i = 0; i < intervalsSize; i++){
+        result[i] = malloc(sizeof (int ) * 2);
+    }
+    qsort(intervals, intervalsSize, sizeof (int *), cmp);
+    int count = 0;
+    for(int i = 0; i < intervalsSize; i++){
+        // 记录区间的左右边界
+        int L = intervals[i][0], R = intervals[i][1];
+        // 如果count为0或者前一区间的右区间小于此时的左边，加入结果中
+        if (count == 0 || result[count - 1][1] < L) {
+            returnColumnSizes[0][count] = 2;
+            result[count][0] = L;
+            result[count][1] = R;
+            count++;
+        } 
+        else{ // 更新右边界的值
+            result[count - 1][1] = max(R, result[count - 1][1]);
+        }
+    }
+    *returnSize = count;
+    return result;
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int[][] Merge(int[][] intervals)
+    {
+        if (intervals.Length == 0)
+            return intervals;
+        Array.Sort(intervals, (a, b) => a[0] - b[0]);
+        List<List<int>> res = new List<List<int>>();
+        res.Add(intervals[0].ToList());
+        for (int i = 1; i < intervals.Length; i++)
+        {
+            if (res[res.Count - 1][1] >= intervals[i][0])
+            {
+                res[res.Count - 1][1] = Math.Max(res[res.Count - 1][1], intervals[i][1]);
+            }
+            else
+            {
+                res.Add(intervals[i].ToList());
+            }
+        }
+        return res.Select(x => x.ToArray()).ToArray();
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0059.螺旋矩阵II.md

@@ -87,11 +87,11 @@ public:
 
             // 下面开始的四个for就是模拟转了一圈
             // 模拟填充上行从左到右(左闭右开)
-            for (j = starty; j < n - offset; j++) {
+            for (j; j < n - offset; j++) {
-                res[startx][j] = count++;
+                res[i][j] = count++;
             }
             // 模拟填充右列从上到下(左闭右开)
-            for (i = startx; i < n - offset; i++) {
+            for (i; i < n - offset; i++) {
                 res[i][j] = count++;
             }
             // 模拟填充下行从右到左(左闭右开)
@@ -138,42 +138,51 @@ public:
 ```Java
 class Solution {
     public int[][] generateMatrix(int n) {
-        int loop = 0;  // 控制循环次数
+        int[][] nums = new int[n][n];
-        int[][] res = new int[n][n];
+        int startX = 0, startY = 0;  // 每一圈的起始点
-        int start = 0;  // 每次循环的开始点(start, start)
+        int offset = 1;
-        int count = 1;  // 定义填充数字
+        int count = 1;  // 矩阵中需要填写的数字
-        int i, j;
+        int loop = 1; // 记录当前的圈数
+        int i, j; // j 代表列, i 代表行;
 
-        while (loop++ < n / 2) { // 判断边界后，loop从1开始
+        while (loop <= n / 2) {
-            // 模拟上侧从左到右
+
-            for (j = start; j < n - loop; j++) {
+            // 顶部
-                res[start][j] = count++;
+            // 左闭右开，所以判断循环结束时， j 不能等于 n - offset
+            for (j = startY; j < n - offset; j++) {
+                nums[startX][j] = count++;
             }
 
-            // 模拟右侧从上到下
+            // 右列
-            for (i = start; i < n - loop; i++) {
+            // 左闭右开，所以判断循环结束时， i 不能等于 n - offset
-                res[i][j] = count++;
+            for (i = startX; i < n - offset; i++) {
+                nums[i][j] = count++;
             }
 
-            // 模拟下侧从右到左
+            // 底部
-            for (; j >= loop; j--) {
+            // 左闭右开，所以判断循环结束时， j != startY
-                res[i][j] = count++;
+            for (; j > startY; j--) {
+                nums[i][j] = count++;
             }
 
-            // 模拟左侧从下到上
+            // 左列
-            for (; i >= loop; i--) {
+            // 左闭右开，所以判断循环结束时， i != startX
-                res[i][j] = count++;
+            for (; i > startX; i--) {
+                nums[i][j] = count++;
             }
-            start++;
+            startX++;
+            startY++;
+            offset++;
+            loop++;
         }
-
+        if (n % 2 == 1) { // n 为奇数时，单独处理矩阵中心的值
-        if (n % 2 == 1) {
+            nums[startX][startY] = count;
-            res[start][start] = count;
         }
-
+        return nums;
-        return res;
     }
 }
+
+
 ```
 
 ### python3:
@@ -207,6 +216,50 @@ class Solution:
         return nums
 ```
 
+版本二：定义四个边界
+```python
+class Solution(object):
+    def generateMatrix(self, n):
+        if n <= 0:
+            return []
+        
+        # 初始化 n x n 矩阵
+        matrix = [[0]*n for _ in range(n)]
+
+        # 初始化边界和起始值
+        top, bottom, left, right = 0, n-1, 0, n-1
+        num = 1
+
+        while top <= bottom and left <= right:
+            # 从左到右填充上边界
+            for i in range(left, right + 1):
+                matrix[top][i] = num
+                num += 1
+            top += 1
+
+            # 从上到下填充右边界
+            for i in range(top, bottom + 1):
+                matrix[i][right] = num
+                num += 1
+            right -= 1
+
+            # 从右到左填充下边界
+
+            for i in range(right, left - 1, -1):
+                matrix[bottom][i] = num
+                num += 1
+            bottom -= 1
+
+            # 从下到上填充左边界
+
+            for i in range(bottom, top - 1, -1):
+                matrix[i][left] = num
+                num += 1
+            left += 1
+
+        return matrix
+```
+
 ### JavaScript:
 
 ```javascript

problems/0062.不同路径.md

@@ -536,8 +536,29 @@ object Solution {
 ```
 
 ### c#
+```csharp
+// 二维数组
+public class Solution
+{
+    public int UniquePaths(int m, int n)
+    {
+        int[,] dp = new int[m, n];
+        for (int i = 0; i < m; i++) dp[i, 0] = 1;
+        for (int j = 0; j < n; j++) dp[0, j] = 1;
+        for (int i = 1; i < m; i++)
+        {
+            for (int j = 1; j < n; j++)
+            {
+                dp[i, j] = dp[i - 1, j] + dp[i, j - 1];
+            }
+        }
+        return dp[m - 1, n - 1];
+    }
+}
+```
 
-```c#
+```csharp
+// 一维数组
 public class Solution
 {
     public int UniquePaths(int m, int n)

problems/0063.不同路径II.md

@@ -734,6 +734,30 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int UniquePathsWithObstacles(int[][] obstacleGrid)
+    {
+        int m = obstacleGrid.Length;
+        int n = obstacleGrid[0].Length;
+        int[,] dp = new int[m, n];
+        if (obstacleGrid[0][0] == 1 || obstacleGrid[m - 1][n - 1] == 1) return 0;
+        for (int i = 0; i < m && obstacleGrid[i][0] == 0; i++) dp[i, 0] = 1;
+        for (int j = 0; j < n && obstacleGrid[0][j] == 0; j++) dp[0, j] = 1;
+        for (int i = 1; i < m; i++)
+        {
+            for (int j = 1; j < n; j++)
+            {
+                if (obstacleGrid[i][j] == 1) continue;
+                dp[i, j] = dp[i - 1, j] + dp[i, j - 1];
+            }
+        }
+        return dp[m - 1, n - 1];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0070.爬楼梯.md

@@ -468,7 +468,7 @@ object Solution {
 
 ### C#
 
-```c#
+```csharp
 public class Solution {
     public int ClimbStairs(int n) {
         if(n<=2) return n;

problems/0070.爬楼梯完全背包版本.md

@@ -169,7 +169,32 @@ class climbStairs{
 
 
 ### Go：
+```go
+func climbStairs(n int, m int) int {
+    dp := make([]int, n+1)
+    dp[0] = 1   
+    for i := 1; i <= n; i++ {
+        for j := 1; j <= m; j++ {
+            if i-j >= 0 {
+                dp[i] += dp[i-j]
+            }
+        }
+    }   
+    return dp[n]
+}
 
+func main() {
+    // 读取输入n,m
+    reader := bufio.NewReader(os.Stdin)
+    input, _ := reader.ReadString('\n')
+    input = strings.TrimSpace(input)
+    nv := strings.Split(input, " ")
+    n, _ := strconv.Atoi(nv[0])
+    m, _ := strconv.Atoi(nv[1]) 
+    result := climbStairs(n, m)
+    fmt.Println(result)
+}
+```
 
 ### JavaScript:
 

problems/0077.组合.md

@@ -793,7 +793,7 @@ end
 
 ```
 ### C#
-```C#
+```csharp
 // 暴力
 public class Solution
 {

problems/0090.子集II.md

@@ -158,13 +158,6 @@ public:
 
 其实这道题目的知识点，我们之前都讲过了，如果之前讲过的子集问题和去重问题都掌握的好，这道题目应该分分钟AC。
 
-当然本题去重的逻辑，也可以这么写
-
-```cpp
-if (i > startIndex && nums[i] == nums[i - 1] ) {
-	continue;
-}
-```
 
 ## 其他语言版本
 
@@ -641,7 +634,7 @@ object Solution {
 }
 ```
 ### C#
-```c#
+```csharp
 public class Solution
 {
     public IList<IList<int>> res = new List<IList<int>>();

problems/0096.不同的二叉搜索树.md

@@ -328,6 +328,25 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int NumTrees(int n)
+    {
+        int[] dp = new int[n + 1];
+        dp[0] = 1;
+        for (int i = 1; i <= n; i++)
+        {
+            for (int j = 1; j <= i; j++)
+            {
+                dp[i] += dp[j - 1] * dp[i - j];
+            }
+        }
+        return dp[n];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0098.验证二叉搜索树.md

@@ -792,7 +792,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public long val = Int64.MinValue;
 public bool IsValidBST(TreeNode root)

problems/0101.对称二叉树.md

@@ -898,7 +898,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public bool IsSymmetric(TreeNode root)
 {

problems/0102.二叉树的层序遍历.md

@@ -463,7 +463,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public IList<IList<int>> LevelOrder(TreeNode root)
 {
     var res = new List<IList<int>>();
@@ -825,7 +825,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public IList<IList<int>> LevelOrderBottom(TreeNode root)
 {
     var res = new List<IList<int>>();

problems/0104.二叉树的最大深度.md

@@ -1033,7 +1033,10 @@ impl Solution {
     }
 ```
 ### C#
-```C#
+
+0104.二叉树的最大深度
+
+```csharp
 // 递归法
 public int MaxDepth(TreeNode root) {
     if(root == null) return 0;
@@ -1044,7 +1047,7 @@ public int MaxDepth(TreeNode root) {
     return 1 + Math.Max(leftDepth, rightDepth);
 }
 ```
-```C#
+```csharp
 // 前序遍历
 int result = 0;
 public int MaxDepth(TreeNode root)
@@ -1065,7 +1068,7 @@ public void GetDepth(TreeNode root, int depth)
     return;
 }
 ```
-```C#
+```csharp
 // 迭代法
 public int MaxDepth(TreeNode root)
 {
@@ -1088,7 +1091,76 @@ public int MaxDepth(TreeNode root)
 }
 ```
 
+559.n叉树的最大深度 
+递归法
+```csharp
+     /*
+     递归法
+     */
+     public class Solution {
+       public int MaxDepth(Node root) {
+           int res = 0;
+           /* 终止条件 */
+           if(root == null){
+               return 0;
+           }
+
+           /* logic */
+           // 遍历当前节点的子节点
+           for (int i = 0; i < root.children.Count; i++)
+           {
+               res =  Math.Max(res, MaxDepth(root.children[i]));
+           }
+           return res + 1;
+       }
+     }
+     // @lc code=end
+```
+    迭代法（层序遍历）
+```csharp
+   /*
+   迭代法
+   */
+   public class Solution
+   {
+       public int MaxDepth(Node root)
+       {
+           Queue<Node> que = new Queue<Node>(); // 使用泛型队列存储节点
+
+           int res = 0;
+
+           if(root != null){
+               que.Enqueue(root); // 将根节点加入队列
+           }
+           while (que.Count > 0)
+           {
+               int size = que.Count; // 获取当前层的节点数
+               res++; // 深度加一
+
+               for (int i = 0; i < size; i++)
+               {
+                   // 每一层的遍历
+
+                   var curNode = que.Dequeue(); // 取出队列中的节点
+                   for (int j = 0; j < curNode.children.Count; j++)
+                   {
+                       if (curNode.children[j] != null)
+                       {
+                           que.Enqueue(curNode.children[j]); // 将子节点加入队列
+                       }
+                   }
+               }
+           }
+
+           return res; // 返回树的最大深度
+
+       }
+   }
+```
+
+
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0106.从中序与后序遍历序列构造二叉树.md

@@ -1229,7 +1229,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public TreeNode BuildTree(int[] inorder, int[] postorder)
 {
     if (inorder.Length == 0 || postorder.Length == null) return null;

problems/0110.平衡二叉树.md

@@ -909,7 +909,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public bool IsBalanced(TreeNode root)
 {
     return GetHeight(root) == -1 ? false : true;

problems/0111.二叉树的最小深度.md

@@ -709,7 +709,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public int MinDepth(TreeNode root)
 {
@@ -725,7 +725,7 @@ public int MinDepth(TreeNode root)
     return res;
 }
 ```
-```C#
+```csharp
 // 迭代
 public int MinDepth(TreeNode root)
 {

problems/0112.路径总和.md

@@ -1513,7 +1513,7 @@ impl Solution {
 
 ```
 ### C#
-```C#
+```csharp
 // 0112.路径总和
 // 递归 
 public bool HasPathSum(TreeNode root, int targetSum)
@@ -1523,8 +1523,64 @@ public bool HasPathSum(TreeNode root, int targetSum)
     return HasPathSum(root.left, targetSum - root.val) || HasPathSum(root.right, targetSum - root.val);
 }
 ```
+0113.路径总和：
+```csharp
+/*
+ * @lc app=leetcode id=113 lang=csharp
+ * 0113.路径总和 II
+ * [113] Path Sum II
+ * 递归法
+ */
+public class Solution {
+    private List<List<int>> result = new List<List<int>>();
+    private List<int> path = new List<int>();
 
+    // Main function to find paths with the given sum
+    public IList<IList<int>> PathSum(TreeNode root, int targetSum) {
+        result.Clear();
+        path.Clear();
+        if (root == null) return result.Select(list => list as IList<int>).ToList();
+        path.Add(root.val); // Add the root node to the path
+        traversal(root, targetSum - root.val); // Start the traversal
+        return result.Select(list => list as IList<int>).ToList();
+    }
+
+    // Recursive function to traverse the tree and find paths
+    private void traversal(TreeNode node, int count) {
+        // If a leaf node is reached and the target sum is achieved
+        if (node.left == null && node.right == null && count == 0) {
+            result.Add(new List<int>(path)); // Add a copy of the path to the result
+            return;
+        }
+
+        // If a leaf node is reached and the target sum is not achieved, or if it's not a leaf node
+        if (node.left == null && node.right == null) return;
+
+        // Traverse the left subtree
+        if (node.left != null) {
+            path.Add(node.left.val);
+            count -= node.left.val;
+            traversal(node.left, count);    // Recursive call
+            count += node.left.val;        // Backtrack
+            path.RemoveAt(path.Count - 1); // Backtrack
+        }
+
+        // Traverse the right subtree
+        if (node.right != null) {
+            path.Add(node.right.val);
+            count -= node.right.val;
+            traversal(node.right, count);   // Recursive call
+            count += node.right.val;       // Backtrack
+            path.RemoveAt(path.Count - 1); // Backtrack
+        }
+    }
+}
+
+// @lc code=end
+
+```
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0116.填充每个节点的下一个右侧节点指针.md

@@ -358,7 +358,84 @@ function connect(root: NodePro | null): NodePro | null {
 };
 ```
 
+```csharp
+//递归
+public class Solution {
+    public Node Connect(Node root) {
+        if (root == null) {
+            return null;
+        }
         
+        ConnectNodes(root.left, root.right);
+        
+        return root;
+    }
+
+    private void ConnectNodes(Node node1, Node node2) {
+        if (node1 == null || node2 == null) {
+            return;
+        }
+
+        // 将左子节点的 next 指向右子节点
+        node1.next = node2;
+
+        // 递归连接当前节点的左右子节点
+        ConnectNodes(node1.left, node1.right);
+        ConnectNodes(node2.left, node2.right);
+
+        // 连接跨越父节点的两个子树
+        ConnectNodes(node1.right, node2.left);
+    }
+}
+
+
+// 迭代
+public class Solution
+{
+    public Node Connect(Node root)
+    {
+        Queue<Node> que = new Queue<Node>();
+
+        if (root != null)
+        {
+            que.Enqueue(root);
+        }
+
+        while (que.Count > 0)
+        {
+
+            var queSize = que.Count;
+            for (int i = 0; i < queSize; i++)
+            {
+                var cur = que.Dequeue();
+
+                // 当这个节点不是这一层的最后的节点
+                if (i != queSize - 1)
+                {
+                    // 当前节点指向下一个节点
+                    cur.next = que.Peek();
+                }
+                // 否则指向空
+                else
+                {
+                    cur.next = null;
+                }
+
+                if (cur.left != null)
+                {
+                    que.Enqueue(cur.left);
+                }
+                if (cur.right != null)
+                {
+                    que.Enqueue(cur.right);
+                }
+            }
+        }
+
+        return root;
+    }
+}
+```
 
 
 <p align="center">

problems/0121.买卖股票的最佳时机.md

@@ -531,6 +531,52 @@ public class Solution
 }
 ```
 
+### C：
+
+> 贪心
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) > (b) ? (b) : (a))
+
+int maxProfit(int* prices, int pricesSize) {
+    int low = INT_MIN;
+    int result = 0;
+    for(int i = 0; i < pricesSize; i++){
+        low = min(low, prices[i]);
+        result = max(result, prices[i] - low);
+    }
+    return result;
+}
+```
+
+> 动态规划
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int maxProfit(int* prices, int pricesSize){
+    if(pricesSize == 0){
+        return 0;
+    }
+    // dp初始化
+    int ** dp = malloc(sizeof (int *) * pricesSize);
+    for(int i = 0; i < pricesSize; i++){
+        dp[i] = malloc(sizeof (int ) * 2);
+    }
+    // 下标0表示持有股票的情况下的最大现金，下标1表示不持有股票的情况下获得的最大现金
+    dp[0][0] = -prices[0];
+    dp[0][1] = 0;
+    for(int i = 1; i < pricesSize; i++){
+        dp[i][0] = max(dp[i - 1][0], - prices[i]);
+        dp[i][1] = max(dp[i - 1][1], dp[i - 1][0] + prices[i]);
+    }
+    return dp[pricesSize - 1][1];
+}
+```
+
+
+
 ### Rust:
 
 > 贪心
@@ -568,4 +614,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0122.买卖股票的最佳时机II（动态规划）.md

@@ -365,6 +365,49 @@ public class Solution
 }
 ```
 
+### C:
+
+> 动态规划
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int maxProfit(int* prices, int pricesSize){
+    int **dp = malloc(sizeof (int *) * pricesSize);
+    for (int i = 0; i < pricesSize; ++i) {
+        dp[i] = malloc(sizeof (int ) * 2);
+    }
+    // 0表示持有该股票所得最大，1表示不持有所得最大
+    dp[0][0] = -prices[0];
+    dp[0][1] = 0;
+    for (int i = 1; i < pricesSize; ++i) {
+        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]);
+    }
+    return dp[pricesSize - 1][1];
+}
+```
+
+> 贪心
+
+```c
+int maxProfit(int* prices, int pricesSize) {
+    if(pricesSize == 0){
+        return 0;
+    }
+    int result = 0;
+    for(int i = 1; i < pricesSize; i++){
+        // 如果今天股票价格大于昨天，代表有利润
+        if(prices[i] > prices[i - 1]){
+            result += prices[i] - prices[i - 1];
+        }
+    }
+    return result;
+}
+```
+
+
+
 ### Rust:
 
 > 贪心
@@ -416,3 +459,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0123.买卖股票的最佳时机III.md

@@ -413,6 +413,34 @@ function maxProfit(prices: number[]): number {
 };
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) > (b) ? (b) : (a))
+
+int maxProfit(int* prices, int pricesSize) {
+    int buy1 = prices[0], buy2 = prices[0];
+    int profit1 = 0, profit2 = 0;
+    for (int i = 0; i < pricesSize; ++i) {
+        // 寻找最低点买入
+        buy1 = min(buy1, prices[i]);
+        // 找到第一次交易的最大盈利,并不断维护这一最大值
+        profit1 = max(profit1, prices[i] - buy1);
+
+        // 寻找第二次交易的最低投资点，并且考虑前一次交易的成本
+        // 当前价格 - 第一次操作的盈利=新的投入成本（
+        // 为了让盈利最大，要寻找最小的成本）
+        buy2 = min(buy2, prices[i] - profit1);
+        // 第二次卖出后的盈利：当前价格减去成本，不断维护这一最大的总利润
+        profit2 = max(profit2, prices[i] - buy2);
+    }
+    return profit2;
+}
+```
+
+
+
 ### Rust：
 
 > 版本一
@@ -465,4 +493,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0127.单词接龙.md

@@ -198,7 +198,7 @@ class Solution {
 
 ### Python 
 
-```
+```python
 class Solution:
     def ladderLength(self, beginWord: str, endWord: str, wordList: List[str]) -> int:
         wordSet = set(wordList)

problems/0130.被围绕的区域.md

@@ -561,6 +561,237 @@ function solve(board) {
 }
 ```
 
+### Go
+
+dfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+
+func solve(board [][]byte) {
+	rows, cols := len(board), len(board[0])
+	// 列
+	for i := 0; i < rows; i++ {
+		if board[i][0] == 'O' {
+			dfs(board, i, 0)
+		}
+		if board[i][cols-1] == 'O' {
+			dfs(board, i, cols-1)
+		}
+	}
+	// 行
+	for j := 0; j < cols; j++ {
+		if board[0][j] == 'O' {
+			dfs(board, 0, j)
+		}
+		if board[rows-1][j] == 'O' {
+			dfs(board, rows-1, j)
+		}
+	}
+
+	for _, r := range board {
+		for j, c := range r {
+			if c == 'A' {
+				r[j] = 'O'
+				continue
+			}
+			if c == 'O' {
+				r[j] = 'X'
+			}
+		}
+	}
+}
+
+func dfs(board [][]byte, i, j int) {
+	board[i][j] = 'A'
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(board) || y < 0 || y >= len(board[0]) {
+			continue
+		}
+		if board[x][y] == 'O' {
+			dfs(board, x, y)
+		}
+	}
+}
+```
+
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+
+func solve(board [][]byte) {
+	rows, cols := len(board), len(board[0])
+	// 列
+	for i := 0; i < rows; i++ {
+		if board[i][0] == 'O' {
+			bfs(board, i, 0)
+		}
+		if board[i][cols-1] == 'O' {
+			bfs(board, i, cols-1)
+		}
+	}
+	// 行
+	for j := 0; j < cols; j++ {
+		if board[0][j] == 'O' {
+			bfs(board, 0, j)
+		}
+		if board[rows-1][j] == 'O' {
+			bfs(board, rows-1, j)
+		}
+	}
+
+	for _, r := range board {
+		for j, c := range r {
+			if c == 'A' {
+				r[j] = 'O'
+                         	continue
+			}
+			if c == 'O' {
+				r[j] = 'X'
+			}
+		}
+	}
+}
+
+func bfs(board [][]byte, i, j int) {
+	queue := [][]int{{i, j}}
+	board[i][j] = 'A'
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(board) || y < 0 || y >= len(board[0]) {
+				continue
+			}
+			if board[x][y] == 'O' {
+				board[x][y] = 'A'
+				queue = append(queue, []int{x, y})
+			}
+		}
+	}
+}
+```
+
+### Rust
+
+bfs:
+
+```rust
+impl Solution {
+    const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
+    pub fn solve(board: &mut Vec<Vec<char>>) {
+        let (rows, cols) = (board.len(), board[0].len());
+        // 列
+        for i in 0..rows {
+            if board[i][0] == 'O' {
+                Self::dfs(board, i, 0);
+            }
+            if board[i][cols - 1] == 'O' {
+                Self::dfs(board, i, cols - 1);
+            }
+        }
+        //行
+        for j in 0..cols {
+            if board[0][j] == 'O' {
+                Self::dfs(board, 0, j);
+            }
+            if board[rows - 1][j] == 'O' {
+                Self::dfs(board, rows - 1, j);
+            }
+        }
+
+        for v in board.iter_mut() {
+            for c in v.iter_mut() {
+                if *c == 'A' {
+                    *c = 'O';
+                    continue;
+                }
+                if *c == 'O' {
+                    *c = 'X';
+                }
+            }
+        }
+    }
+
+    pub fn dfs(board: &mut [Vec<char>], i: usize, j: usize) {
+        board[i][j] = 'A';
+        for (d1, d2) in Self::DIRECTIONS {
+            let (x, y) = (i as isize + d1, j as isize + d2);
+            if x < 0 || x >= board.len() as isize || y < 0 || y >= board[0].len() as isize {
+                continue;
+            }
+            let (x, y) = (x as usize, y as usize);
+            if board[x][y] == 'O' {
+                Self::dfs(board, x, y);
+            }
+        }
+    }
+}
+```
+
+bfs:
+
+```rust
+use std::collections::VecDeque;
+impl Solution {
+    const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
+    pub fn solve(board: &mut Vec<Vec<char>>) {
+        let (rows, cols) = (board.len(), board[0].len());
+        // 列
+        for i in 0..rows {
+            if board[i][0] == 'O' {
+                Self::bfs(board, i, 0);
+            }
+            if board[i][cols - 1] == 'O' {
+                Self::bfs(board, i, cols - 1);
+            }
+        }
+        //行
+        for j in 0..cols {
+            if board[0][j] == 'O' {
+                Self::bfs(board, 0, j);
+            }
+            if board[rows - 1][j] == 'O' {
+                Self::bfs(board, rows - 1, j);
+            }
+        }
+
+        for v in board.iter_mut() {
+            for c in v.iter_mut() {
+                if *c == 'A' {
+                    *c = 'O';
+                    continue;
+                }
+                if *c == 'O' {
+                    *c = 'X';
+                }
+            }
+        }
+    }
+
+    pub fn bfs(board: &mut [Vec<char>], i: usize, j: usize) {
+        let mut queue = VecDeque::from([(i, j)]);
+        board[i][j] = 'A';
+        while let Some((i, j)) = queue.pop_front() {
+            for (d1, d2) in Self::DIRECTIONS {
+                let (x, y) = (i as isize + d1, j as isize + d2);
+                if x < 0 || x >= board.len() as isize || y < 0 || y >= board[0].len() as isize {
+                    continue;
+                }
+                let (x, y) = (x as usize, y as usize);
+                if board[x][y] == 'O' {
+                    board[x][y] = 'A';
+                    queue.push_back((x, y));
+                }
+            }
+        }
+    }
+}
+```
+
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>

problems/0139.单词拆分.md

@@ -498,6 +498,33 @@ function wordBreak(s: string, wordDict: string[]): boolean {
 };
 ```
 
+### C
+
+```c
+bool wordBreak(char* s, char** wordDict, int wordDictSize) {
+    int len = strlen(s);
+    // 初始化
+    bool dp[len + 1];
+    memset(dp, false, sizeof (dp));
+    dp[0] = true;
+    for (int i = 1; i < len + 1; ++i) {
+        for(int j =  0; j < wordDictSize; j++){
+            int wordLen = strlen(wordDict[j]);
+            // 分割点是由i和字典单词长度决定
+            int k = i - wordLen;
+            if(k < 0){
+                continue;
+            }
+            // 这里注意要限制长度，故用strncmp
+            dp[i] = (dp[k] && !strncmp(s + k, wordDict[j], wordLen)) || dp[i];
+        }
+    }
+    return dp[len];
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -521,4 +548,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0151.翻转字符串里的单词.md

@@ -973,7 +973,7 @@ char * reverseWords(char * s){
 ```
 
 ### C#
-```C# LINQ高级方法
+```csharp LINQ高级方法
 public string ReverseWords(string s) {
     return string.Join(' ', s.Trim().Split(' ',StringSplitOptions.RemoveEmptyEntries).Reverse());
 }

problems/0188.买卖股票的最佳时机IV.md

@@ -474,6 +474,34 @@ function maxProfit(k: number, prices: number[]): number {
 };
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int maxProfit(int k, int* prices, int pricesSize) {
+    if(pricesSize == 0){
+        return 0;
+    }
+    
+    int dp[pricesSize][2 * k + 1];
+    memset(dp, 0, sizeof(int) * pricesSize * (2 * k + 1));
+    for (int j = 1; j < 2 * k; j += 2) {
+        dp[0][j] = -prices[0];
+    }
+
+    for (int i = 1;i < pricesSize; i++) {//枚举股票
+        for (int j = 0; j < 2 * k - 1; j += 2) { //更新每一次买入卖出
+            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[pricesSize - 1][2 * k];
+}
+```
+
+
+
 ### Rust：
 
 ```rust
@@ -529,3 +557,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0198.打家劫舍.md

@@ -315,6 +315,31 @@ function rob(nums: number[]): number {
 };
 ```
 
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int rob(int* nums, int numsSize) {
+    if(numsSize == 0){
+        return 0;
+    }
+    if(numsSize == 1){
+        return nums[0];
+    }
+    // dp初始化
+    int dp[numsSize];
+    dp[0] = nums[0];
+    dp[1] = max(nums[0], nums[1]);
+    for(int i = 2; i < numsSize; i++){
+        dp[i] = max(dp[i - 1], dp[i - 2] + nums[i]);
+    }
+    return dp[numsSize - 1];
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -339,3 +364,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0200.岛屿数量.广搜版.md

@@ -199,7 +199,9 @@ class Solution {
 
 
 ### Python
+
 BFS solution 
+
 ```python
 class Solution:
     def __init__(self):
@@ -240,6 +242,7 @@ class Solution:
 
 ```
 ### JavaScript
+
 ```javascript
 var numIslands = function (grid) {
     let dir = [[0, 1], [1, 0], [-1, 0], [0, -1]]; // 四个方向
@@ -321,11 +324,53 @@ function numIslands2(grid: string[][]): number {
 }
 ```
 
+### Go
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+
+func numIslands(grid [][]byte) int {
+	res := 0
+
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == '1' && !visited[i][j] {
+				res++
+				bfs(grid, visited, i, j)
+			}
+		}
+	}
+	return res
+}
+
+func bfs(grid [][]byte, visited [][]bool, i, j int) {
+	queue := [][2]int{{i, j}}
+	visited[i][j] = true // 标记已访问，循环中标记会导致重复
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+				continue
+			}
+			if grid[x][y] == '1' && !visited[x][y] {
+				visited[x][y] = true
+				queue = append(queue, [2]int{x, y})
+			}
+		}
+	}
+}
+```
 
 ### Rust
 
 ```rust
-
 use std::collections::VecDeque;
 impl Solution {
     const DIRECTIONS: [(i32, i32); 4] = [(0, 1), (1, 0), (-1, 0), (0, -1)];

problems/0200.岛屿数量.深搜版.md

@@ -37,7 +37,7 @@
 
 在遇到标记过的陆地节点和海洋节点的时候直接跳过。 这样计数器就是最终岛屿的数量。
 
-那么如果把节点陆地所能遍历到的陆地都标记上呢，就可以使用 DFS，BFS或者并查集。 
+那么如何把节点陆地所能遍历到的陆地都标记上呢，就可以使用 DFS，BFS或者并查集。 
 
 ### 深度优先搜索 
 
@@ -389,50 +389,41 @@ function numIslands(grid: string[][]): number {
 ### Go
 
 ```go
+
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+
 func numIslands(grid [][]byte) int {
-    // 用1标记已访问
+	res := 0
-    visited := make([][]int, len(grid))
-    for i := 0; i < len(visited); i++{
-        visited[i] = make([]int, len(grid[0]))
-    }
 
-    var bfs func(x, y int)
+	visited := make([][]bool, len(grid))
-    bfs = func(x, y int){
+	for i := 0; i < len(grid); i++ {
-        stack := make([][]int, 0)
+		visited[i] = make([]bool, len(grid[0]))
-        stack = append(stack, []int{x, y})
+	}
-        moveX := []int{1, -1, 0, 0}
-        moveY := []int{0, 0, 1, -1} 
 
-        for len(stack) != 0{
+	for i, rows := range grid {
-            node := stack[len(stack) - 1]
+		for j, v := range rows {
-            stack = stack[:len(stack) - 1]
+			if v == '1' && !visited[i][j] {
+				res++
+				dfs(grid, visited, i, j)
+			}
+		}
+	}
 
-            for i := 0; i < 4; i++{
+	return res
-                dx := moveX[i] + node[0]
+}
-                dy := moveY[i] + node[1]
-                if dx < 0 || dx >= len(grid) || dy < 0 || dy >= len(grid[0]) || visited[dx][dy] == 1{
-                    continue
-                }
-                visited[dx][dy] = 1
-                if grid[dx][dy] == '1'{
-                    stack = append(stack, []int{dx,dy})
-                }
-            }
-        }
-    }
 
-    result := 0
+func dfs(grid [][]byte, visited [][]bool, i, j int) {
-    for i := 0; i < len(grid); i++{
+        visited[x][y] = true
-        for j := 0; j < len(grid[0]); j++{
+	for _, d := range DIRECTIONS {
-            if visited[i][j] == 0 && grid[i][j] == '1'{
+		x, y := i+d[0], j+d[1]
-                bfs(i, j)
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
-                visited[i][j] = 1
+			continue
-                result++
+		}
-            }
+		if grid[x][y] == '1' && !visited[x][y] {
-        }
+			dfs(grid, visited, x, y)
-    }
+		}
+	}
 
-    return result
 }
 ```
 

problems/0213.打家劫舍II.md

@@ -308,6 +308,34 @@ function robRange(nums: number[], start: number, end: number): number {
 }
 ```
 
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+// 198.打家劫舍的逻辑
+int robRange(int* nums, int start, int end, int numsSize) {
+    if (end == start) return nums[start];
+    int dp[numsSize];
+    dp[start] = nums[start];
+    dp[start + 1] = max(nums[start], nums[start + 1]);
+    for (int i = start + 2; i <= end; i++) {
+        dp[i] = max(dp[i - 2] + nums[i], dp[i - 1]);
+    }
+    return dp[end];
+}
+
+int rob(int* nums, int numsSize) {
+    if (numsSize == 0) return 0;
+    if (numsSize == 1) return nums[0];
+    int result1 = robRange(nums, 0, numsSize - 2, numsSize); // 情况二
+    int result2 = robRange(nums, 1, numsSize - 1, numsSize); // 情况三
+    return max(result1, result2);
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -343,4 +371,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0222.完全二叉树的节点个数.md

@@ -868,7 +868,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public int CountNodes(TreeNode root)
 {

problems/0225.用队列实现栈.md

@@ -1046,6 +1046,8 @@ class MyStack() {
 
 ### C#:
 
+> 双队列
+
 ```csharp
 public class MyStack {
     Queue<int> queue1;
@@ -1080,6 +1082,54 @@ public class MyStack {
 }
 ```
 
+> 单队列
+
+```c#
+/*
+ * @lc app=leetcode id=225 lang=csharp
+ * 版本二：单队列
+ * [225] Implement Stack using Queues
+ */
+
+// @lc code=start
+public class MyStack {
+    Queue<int> myQueue;
+    public MyStack() {
+        myQueue = new Queue<int>();
+    }
+    
+    public void Push(int x) {
+        myQueue.Enqueue(x);
+    }
+    
+    //使用一个队列实现
+    public int Pop() {
+        //一个队列在模拟栈弹出元素的时候只要将队列头部的元素（除了最后一个元素外） 重新添加到队列尾部，此时再去弹出元素就是栈的顺序了。
+        for (var i = 0; i < myQueue.Count-1; i++)
+        {
+            myQueue.Enqueue(myQueue.Dequeue());
+        }
+        return myQueue.Dequeue();
+    }
+
+    //复用Pop()的代码
+    public int Top() {
+        int res = Pop();
+        myQueue.Enqueue(res);
+        return res;
+    }
+    
+    public bool Empty() {
+        return (myQueue.Count == 0);
+    }
+}
+
+// @lc code=end
+
+```
+
+
+
 ### PHP:
 
 > 双队列
@@ -1203,3 +1253,4 @@ impl MyStack {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0235.二叉搜索树的最近公共祖先.md

@@ -298,7 +298,7 @@ class Solution:
         return self.traversal(root, p, q)
 ```
 
-迭代法（版本二）精简
+递归法（版本二）精简
 ```python
 class Solution:
     def lowestCommonAncestor(self, root, p, q):
@@ -521,7 +521,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
 {

problems/0236.二叉树的最近公共祖先.md

@@ -432,7 +432,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
 {
     if (root == null || root == p || root == q) return root;

problems/0257.二叉树的所有路径.md

@@ -901,7 +901,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public IList<string> BinaryTreePaths(TreeNode root)
 {
     List<int> path = new();

problems/0279.完全平方数.md

@@ -389,6 +389,30 @@ function numSquares(n: number): number {
 };
 ```
 
+## C
+
+```c
+#define min(a, b) ((a) > (b) ? (b) : (a))
+
+int numSquares(int n) {
+    int* dp = (int*)malloc(sizeof(int) * (n + 1));
+    for (int j = 0; j < n + 1; j++) {
+        dp[j] = INT_MAX;
+    }
+    dp[0] = 0;
+     // 遍历背包
+    for (int i = 0; i <= n; ++i) {
+        // 遍历物品
+        for (int j = 1; j * j <= i; ++j) {
+            dp[i] = min(dp[i - j * j] + 1, dp[i]);
+        }
+    }
+    return dp[n];
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -439,4 +463,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0300.最长上升子序列.md

@@ -288,6 +288,36 @@ function lengthOfLIS(nums: number[]): number {
 };
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int lengthOfLIS(int* nums, int numsSize) {
+    if(numsSize <= 1){
+        return numsSize;
+    }
+    int dp[numsSize];
+    for(int i = 0; i < numsSize; i++){
+        dp[i]=1;
+    }
+    int result = 1;
+    for (int i = 1; i < numsSize; ++i) {
+        for (int j = 0; j < i; ++j) {
+            if(nums[i] > nums[j]){
+                dp[i] = max(dp[i], dp[j] + 1);
+            }
+            if(dp[i] > result){
+                result = dp[i];
+            }
+        }
+    }
+    return result;
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -311,4 +341,3 @@ pub fn length_of_lis(nums: Vec<i32>) -> i32 {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0309.最佳买卖股票时机含冷冻期.md

@@ -457,6 +457,40 @@ function maxProfit(prices: number[]): number {
 };
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+/**
+ * 状态一：持有股票状态（今天买入股票，
+ * 或者是之前就买入了股票然后没有操作，一直持有）
+ * 不持有股票状态，这里就有两种卖出股票状态
+ * 状态二：保持卖出股票的状态（两天前就卖出了股票，度过一天冷冻期。
+ * 或者是前一天就是卖出股票状态，一直没操作）
+ * 状态三：今天卖出股票
+ * 状态四：今天为冷冻期状态，但冷冻期状态不可持续，只有一天！
+
+ */
+int maxProfit(int* prices, int pricesSize) {
+    if(pricesSize == 0){
+        return 0;
+    }
+    int dp[pricesSize][4];
+    memset(dp, 0, sizeof (int ) * pricesSize * 4);
+    dp[0][0] = -prices[0];
+    for (int i = 1; i < pricesSize; ++i) {
+        dp[i][0] = max(dp[i - 1][0], max(dp[i - 1][1] - prices[i], dp[i - 1][3] - 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[pricesSize - 1][1], max(dp[pricesSize - 1][2], dp[pricesSize - 1][3]));
+}
+```
+
+
+
 ### Rust：
 
 ```rust
@@ -486,4 +520,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0322.零钱兑换.md

@@ -352,6 +352,35 @@ func min(a, b int) int {
 
 ```
 
+## C
+
+```c
+#define min(a, b) ((a) > (b) ? (b) : (a))
+
+int coinChange(int* coins, int coinsSize, int amount) {
+    int* dp = (int*)malloc(sizeof(int) * (amount + 1));
+    for (int j = 0; j < amount + 1; j++) {
+        dp[j] = INT_MAX;
+    }
+    dp[0] = 0;
+    // 遍历背包
+    for(int i = 0; i <= amount; i++){
+        // 遍历物品
+        for(int j = 0; j < coinsSize; j++){
+            if(i - coins[j] >= 0 && dp[i - coins[j]] != INT_MAX){
+                dp[i] = min(dp[i], dp[i - coins[j]] + 1);
+            }
+        }
+    }
+    if(dp[amount] == INT_MAX){
+        return -1;
+    }
+    return dp[amount];
+}
+```
+
+
+
 ### Rust:
 
 ```rust
@@ -474,4 +503,3 @@ function coinChange(coins: number[], amount: number): number {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0332.重新安排行程.md

@@ -449,34 +449,37 @@ class Solution:
 ```
 回溯 使用字典
 ```python	
-from collections import defaultdict
-
 class Solution:
     def findItinerary(self, tickets: List[List[str]]) -> List[str]:
-        targets = defaultdict(list)  # 构建机场字典
+        self.adj = {}
-        for ticket in tickets:
-            targets[ticket[0]].append(ticket[1])
-        for airport in targets:
-            targets[airport].sort()  # 对目的地列表进行排序
 
-        path = ["JFK"]  # 起始机场为"JFK"
+        # sort by the destination alphabetically
-        self.backtracking(targets, path, len(tickets))
+        # 根据航班每一站的重点字母顺序排序
-        return path
+        tickets.sort(key=lambda x:x[1])
 
-    def backtracking(self, targets, path, ticketNum):
+        # get all possible connection for each destination
-        if len(path) == ticketNum + 1:
+        # 罗列每一站的下一个可选项
-            return True  # 找到有效行程
+        for u,v in tickets:
+            if u in self.adj: self.adj[u].append(v)
+            else: self.adj[u] = [v]
 
-        airport = path[-1]  # 当前机场
+        # 从JFK出发
-        destinations = targets[airport]  # 当前机场可以到达的目的地列表
+        self.result = []
-        for i, dest in enumerate(destinations):
+        self.dfs("JFK")  # start with JFK
-            targets[airport].pop(i)  # 标记已使用的机票
+
-            path.append(dest)  # 添加目的地到路径
+        return self.result[::-1]  # reverse to get the result
-            if self.backtracking(targets, path, ticketNum):
+
-                return True  # 找到有效行程
+    def dfs(self, s):
-            targets[airport].insert(i, dest)  # 回溯，恢复机票
+        # if depart city has flight and the flight can go to another city
-            path.pop()  # 移除目的地
+        while s in self.adj and len(self.adj[s]) > 0:
-        return False  # 没有找到有效行程
+            # 找到s能到哪里，选能到的第一个机场
+            v = self.adj[s][0]  # we go to the 1 choice of the city
+            # 在之后的可选项机场中去掉这个机场
+            self.adj[s].pop(0)  # get rid of this choice since we used it
+            # 从当前的新出发点开始
+            self.dfs(v)  # we start from the new airport
+
+        self.result.append(s)  # after append, it will back track to last node, thus the result list is in reversed order
 
 ```
 回溯 使用字典 逆序

problems/0337.打家劫舍III.md

@@ -490,6 +490,33 @@ function robNode(node: TreeNode | null): MaxValueArr {
 }
 ```
 
+### C
+
+```c
+int *robTree(struct TreeNode *node) {
+    int* amounts = (int*) malloc(sizeof(int) * 2);
+    memset(amounts, 0, sizeof(int) * 2);
+    if(node == NULL){
+        return amounts;
+    }
+    int * left = robTree(node->left);
+    int * right = robTree(node->right);
+    // 偷当前节点
+    amounts[1] = node->val + left[0] + right[0];
+    // 不偷当前节点
+    amounts[0] = max(left[0], left[1]) + max(right[0], right[1]);
+    return amounts;
+}
+
+int rob(struct TreeNode* root) {
+    int * dp = robTree(root);
+    // 0代表不偷当前节点可以获得的最大值，1表示偷当前节点可以获取的最大值
+    return max(dp[0], dp[1]);
+}
+```
+
+
+
 ### Rust
 
 动态规划：
@@ -523,4 +550,3 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0343.整数拆分.md

@@ -496,6 +496,25 @@ class Solution {
     }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int IntegerBreak(int n)
+    {
+        int[] dp = new int[n + 1];
+        dp[2] = 1;
+        for (int i = 3; i <= n; i++)
+        {
+            for (int j = 1; j <= i / 2; j++)
+            {
+                dp[i] = Math.Max(dp[i],Math.Max(j*(i-j),j*dp[i-j]));
+            }
+        }
+        return dp[n];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0347.前K个高频元素.md

@@ -324,6 +324,34 @@ func topKFrequent(nums []int, k int) []int {
 
 ### JavaScript:
 
+解法一：  
+Leetcode 提供了优先队列的库，具体文档可以参见 [@datastructures-js/priority-queue](https://github.com/datastructures-js/priority-queue/blob/v5/README.md)。  
+
+```js
+var topKFrequent = function (nums, k) {
+  const map = new Map();
+  const res = [];
+  //使用 map 统计元素出现频率
+  for (const num of nums) {
+    map.set(num, (map.get(num) || 0) + 1);
+  }
+  //创建小顶堆
+  const heap = new PriorityQueue({
+    compare: (a, b) => a.value - b.value
+  })
+  for (const [key, value] of map) {
+    heap.enqueue({ key, value });
+    if (heap.size() > k) heap.dequeue();
+  }
+  //处理输出
+  while (heap.size()) res.push(heap.dequeue().key);
+  return res;
+};
+```
+
+解法二：  
+手写实现优先队列  
+
 ```js
 // js 没有堆 需要自己构造
 class Heap {

problems/0349.两个数组的交集.md

@@ -231,6 +231,8 @@ class Solution:
 
 ### Go：
 
+（版本一）使用字典和集合
+
 ```go
 func intersection(nums1 []int, nums2 []int) []int {
     set:=make(map[int]struct{},0)  // 用map模拟set
@@ -251,6 +253,28 @@ func intersection(nums1 []int, nums2 []int) []int {
 }
 ```
 
+（版本二）使用数组
+
+```go
+func intersection(nums1 []int, nums2 []int) []int {
+    count1 := make([]int, 1001, 1001)
+    count2 := make([]int, 1001, 1001)
+    res := make([]int, 0)
+    for _, v := range nums1 {
+        count1[v] = 1
+    }
+    for _, v := range nums2 {
+        count2[v] = 1
+    }
+    for i := 0; i <= 1000; i++ {
+        if count1[i] + count2[i] == 2 {
+            res = append(res, i)
+        }
+    }
+    return res
+}
+```
+
 ### JavaScript:
 
 ```js

problems/0377.组合总和Ⅳ.md

@@ -312,10 +312,52 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+int combinationSum4(int* nums, int numsSize, int target) {
+    int dp[target + 1];
+    memset(dp, 0, sizeof (dp ));
+    dp[0] = 1;
+    for(int i = 0; i <= target; i++){
+        for(int j = 0; j < numsSize; j++){
+            if(i - nums[j] >= 0 && dp[i] < INT_MAX - dp[i - nums[j]]){
+                dp[i] += dp[i - nums[j]];
+            }
+        }
+    }
+    return dp[target];
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int CombinationSum4(int[] nums, int target)
+    {
+        int[] dp = new int[target + 1];
+        dp[0] = 1;
+        for (int i = 0; i <= target; i++)
+        {
+            for (int j = 0; j < nums.Length; j++)
+            {
+                if (i >= nums[j] && dp[i] < int.MaxValue - dp[i - nums[j]])
+                {
+                    dp[i] += dp[i - nums[j]];
+                }
+            }
+        }
+        return dp[target];
+    }
+}
+```
 
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0383.赎金信.md

@@ -216,7 +216,7 @@ class Solution:
 
 (版本六）使用count(简单易懂)
 
-```python3
+```python
 class Solution:
     def canConstruct(self, ransomNote: str, magazine: str) -> bool:
         for char in ransomNote:
@@ -445,6 +445,25 @@ public bool CanConstruct(string ransomNote, string magazine) {
         return true;
     }
 
+```
+
+### C：
+
+```c
+bool canConstruct(char* ransomNote, char* magazine) {
+    // 定义哈希映射数组
+    int hashmap[26] = {0};
+    // 对magazine中字符计数
+    while (*magazine != '\0') hashmap[*magazine++ % 26]++;
+    // 遍历ransomNote，对应的字符自减，小于0说明该字符magazine没有或不足够表示
+    while (*ransomNote != '\0') hashmap[*ransomNote++ % 26]--;
+    // 如果数组中存在负数，说明ransomNote不能由magazine里面的字符构成
+    for (int i = 0; i < 26; i++) {
+        if (hashmap[i] < 0) return false;
+    }
+    return true;
+}
+
 ```
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0404.左叶子之和.md

@@ -652,7 +652,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public int SumOfLeftLeaves(TreeNode root)
 {

problems/0406.根据身高重建队列.md

@@ -396,6 +396,29 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int[][] ReconstructQueue(int[][] people)
+    {
+        Array.Sort(people, (a, b) =>
+        {
+            if (a[0] == b[0])
+            {
+                return a[1] - b[1];
+            }
+            return b[0] - a[0];
+        });
+        var res = new List<int[]>();
+        for (int i = 0; i < people.Length; i++)
+        {
+            res.Insert(people[i][1], people[i]);
+        }
+        return res.ToArray();
+    }
+}
+```
 
 
 <p align="center">

problems/0416.分割等和子集.md

@@ -726,7 +726,35 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public bool CanPartition(int[] nums)
+    {
+        int sum = 0;
+        int[] dp = new int[10001];
+        foreach (int num in nums)
+        {
+            sum += num;
+        }
+        if (sum % 2 == 1) return false;
+        int tartget = sum / 2;
+        for (int i = 0; i < nums.Length; i++)
+        {
+            for (int j = tartget; j >= nums[i]; j--)
+            {
+                dp[j] = Math.Max(dp[j], dp[j - nums[i]] + nums[i]);
+            }
+        }
+        if (dp[tartget] == tartget)
+            return true;
 
+        return false;
+
+    }
+}
+```
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>

problems/0417.太平洋大西洋水流问题.md

@@ -562,7 +562,213 @@ function pacificAtlantic(heights) {
 }
 ```
 
+### go
 
+dfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
+
+func pacificAtlantic(heights [][]int) [][]int {
+	res := make([][]int, 0)
+	pacific := make([][]bool, len(heights))
+	atlantic := make([][]bool, len(heights))
+	for i := 0; i < len(heights); i++ {
+		pacific[i] = make([]bool, len(heights[0]))
+		atlantic[i] = make([]bool, len(heights[0]))
+	}
+	// 列
+	for i := 0; i < len(heights); i++ {
+		dfs(heights, pacific, i, 0)
+		dfs(heights, atlantic, i, len(heights[0])-1)
+	}
+	// 行
+	for j := 0; j < len(heights[0]); j++ {
+		dfs(heights, pacific, 0, j)
+		dfs(heights, atlantic, len(heights)-1, j)
+	}
+
+	for i := 0; i < len(heights); i++ {
+		for j := 0; j < len(heights[0]); j++ {
+			if pacific[i][j] && atlantic[i][j] {
+				res = append(res, []int{i, j})
+			}
+		}
+	}
+
+	return res
+}
+
+func dfs(heights [][]int, visited [][]bool, i, j int) {
+	visited[i][j] = true
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(heights) || y < 0 || y >= len(heights[0]) || heights[i][j] > heights[x][y] || visited[x][y] {
+			continue
+		}
+
+		dfs(heights, visited, x, y)
+	}
+}
+```
+
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
+
+func pacificAtlantic(heights [][]int) [][]int {
+	res := make([][]int, 0)
+	pacific := make([][]bool, len(heights))
+	atlantic := make([][]bool, len(heights))
+	for i := 0; i < len(heights); i++ {
+		pacific[i] = make([]bool, len(heights[0]))
+		atlantic[i] = make([]bool, len(heights[0]))
+	}
+	// 列
+	for i := 0; i < len(heights); i++ {
+		bfs(heights, pacific, i, 0)
+		bfs(heights, atlantic, i, len(heights[0])-1)
+	}
+	// 行
+	for j := 0; j < len(heights[0]); j++ {
+		bfs(heights, pacific, 0, j)
+		bfs(heights, atlantic, len(heights)-1, j)
+	}
+
+	for i := 0; i < len(heights); i++ {
+		for j := 0; j < len(heights[0]); j++ {
+			if pacific[i][j] && atlantic[i][j] {
+				res = append(res, []int{i, j})
+			}
+		}
+	}
+
+	return res
+}
+
+func bfs(heights [][]int, visited [][]bool, i, j int) {
+	queue := make([][]int, 0)
+	queue = append(queue, []int{i, j})
+	visited[i][j] = true
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(heights) || y < 0 || y >= len(heights[0]) || heights[cur[0]][cur[1]] > heights[x][y] || visited[x][y] {
+				continue
+			}
+			queue = append(queue, []int{x, y})
+			visited[x][y] = true
+		}
+	}
+}
+```
+
+### Rust
+
+dfs:
+
+```rust
+impl Solution {
+    const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
+    pub fn pacific_atlantic(heights: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
+        let (m, n) = (heights.len(), heights[0].len());
+        let mut res = vec![];
+        let (mut pacific, mut atlantic) = (vec![vec![false; n]; m], vec![vec![false; n]; m]);
+
+        // 列
+        for i in 0..m {
+            Self::dfs(&heights, &mut pacific, i, 0);
+            Self::dfs(&heights, &mut atlantic, i, n - 1);
+        }
+
+        for j in 0..n {
+            Self::dfs(&heights, &mut pacific, 0, j);
+            Self::dfs(&heights, &mut atlantic, m - 1, j);
+        }
+
+        for i in 0..m {
+            for j in 0..n {
+                if pacific[i][j] && atlantic[i][j] {
+                    res.push(vec![i as i32, j as i32]);
+                }
+            }
+        }
+
+        res
+    }
+
+    pub fn dfs(heights: &[Vec<i32>], visited: &mut [Vec<bool>], i: usize, j: usize) {
+        visited[i][j] = true;
+        for (dx, dy) in Self::DIRECTIONS {
+            let (x, y) = (i as isize + dx, j as isize + dy);
+            if x < 0 || x >= heights.len() as isize || y < 0 || y >= heights[0].len() as isize {
+                continue;
+            }
+            let (x, y) = (x as usize, y as usize);
+            if !visited[x][y] && heights[x][y] >= heights[i][j] {
+                Self::dfs(heights, visited, x, y);
+            }
+        }
+    }
+}
+```
+
+bfs:
+
+```rust
+use std::collections::VecDeque;
+
+impl Solution {
+    const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
+    pub fn pacific_atlantic(heights: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
+        let (m, n) = (heights.len(), heights[0].len());
+        let mut res = vec![];
+        let (mut pacific, mut atlantic) = (vec![vec![false; n]; m], vec![vec![false; n]; m]);
+
+        // 列
+        for i in 0..m {
+            Self::bfs(&heights, &mut pacific, i, 0);
+            Self::bfs(&heights, &mut atlantic, i, n - 1);
+        }
+
+        for j in 0..n {
+            Self::bfs(&heights, &mut pacific, 0, j);
+            Self::bfs(&heights, &mut atlantic, m - 1, j);
+        }
+
+        for i in 0..m {
+            for j in 0..n {
+                if pacific[i][j] && atlantic[i][j] {
+                    res.push(vec![i as i32, j as i32]);
+                }
+            }
+        }
+
+        res
+    }
+
+    pub fn bfs(heights: &[Vec<i32>], visited: &mut [Vec<bool>], i: usize, j: usize) {
+        let mut queue = VecDeque::from([(i, j)]);
+        visited[i][j] = true;
+        while let Some((i, j)) = queue.pop_front() {
+            for (dx, dy) in Self::DIRECTIONS {
+                let (x, y) = (i as isize + dx, j as isize + dy);
+                if x < 0 || x >= heights.len() as isize || y < 0 || y >= heights[0].len() as isize {
+                    continue;
+                }
+                let (x, y) = (x as usize, y as usize);
+                if !visited[x][y] && heights[x][y] >= heights[i][j] {
+                    queue.push_back((x, y));
+                    visited[x][y] = true;
+                }
+            }
+        }
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0435.无重叠区间.md

@@ -423,7 +423,7 @@ object Solution {
 
 ```Rust
 impl Solution {
-    pub fn erase_overlap_intervals(intervals: Vec<Vec<i32>>) -> i32 {
+    pub fn erase_overlap_intervals(mut intervals: Vec<Vec<i32>>) -> i32 {
         if intervals.is_empty() {
             return 0;
         }
@@ -441,6 +441,57 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+// 按照区间右边界排序
+int cmp(const void * var1, const void * var2){
+    return (*(int **) var1)[1] - (*(int **) var2)[1];
+}
+
+int eraseOverlapIntervals(int** intervals, int intervalsSize, int* intervalsColSize) {
+    if(intervalsSize == 0){
+        return 0;
+    }
+    qsort(intervals, intervalsSize, sizeof (int *), cmp);
+    // 记录非重叠的区间数量
+    int count = 1;
+    // 记录区间分割点
+    int end = intervals[0][1];
+    for(int i = 1; i < intervalsSize; i++){
+        if(end <= intervals[i][0]){
+            end = intervals[i][1];
+            count++;
+        }
+    }
+    return intervalsSize - count;
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int EraseOverlapIntervals(int[][] intervals)
+    {
+        if (intervals.Length == 0) return 0;
+        Array.Sort(intervals, (a, b) => a[1].CompareTo(b[1]));
+        int res = 1, end = intervals[0][1];
+        for (int i = 1; i < intervals.Length; i++)
+        {
+            if (end <= intervals[i][0])
+            {
+                end = intervals[i][1];
+                res++;
+            }
+        }
+        return intervals.Length - res;
+    }
+}
+```
 
 
 <p align="center">

problems/0450.删除二叉搜索树中的节点.md

@@ -42,7 +42,7 @@
 
 代码如下：
 
-```
+```cpp
 TreeNode* deleteNode(TreeNode* root, int key)
 ```
 
@@ -50,7 +50,7 @@ TreeNode* deleteNode(TreeNode* root, int key)
 
 遇到空返回，其实这也说明没找到删除的节点，遍历到空节点直接返回了
 
-```
+```cpp
 if (root == nullptr) return root;
 ```
 
@@ -106,7 +106,7 @@ if (root->val == key) {
 
 这里相当于把新的节点返回给上一层，上一层就要用 root->left 或者 root->right接住，代码如下：
 
-```
+```cpp
 if (root->val > key) root->left = deleteNode(root->left, key);
 if (root->val < key) root->right = deleteNode(root->right, key);
 return root;
@@ -772,7 +772,7 @@ impl Solution {
 ### C#
 
 > 递归法：
-```C#
+```csharp
     public TreeNode DeleteNode(TreeNode root, int key) {
         // 第一种情况：没找到删除的节点，遍历到空节点直接返回了
         if (root == null) return null;

problems/0452.用最少数量的箭引爆气球.md

@@ -332,6 +332,24 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int FindMinArrowShots(int[][] points)
+    {
+        if (points.Length == 0) return 0;
+        Array.Sort(points, (a, b) => a[0].CompareTo(b[0]));
+        int count = 1;
+        for (int i = 1; i < points.Length; i++)
+        {
+            if (points[i][0] > points[i - 1][1]) count++;
+            else points[i][1] = Math.Min(points[i][1], points[i - 1][1]);
+        }
+        return count;
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0454.四数相加II.md

@@ -412,6 +412,75 @@ public int FourSumCount(int[] nums1, int[] nums2, int[] nums3, int[] nums4) {
         return res;
     }
 ```
+### C：
+
+```c
+// 哈希表大小
+const int HASH_SIZE = 101;
+
+typedef struct node {
+    int val;
+    int count;
+    struct node *next;
+} node, *HashMap;
+
+// 哈希表插入
+void hash_insert(HashMap hashmap[], int val) {
+    int idx = val < 0 ? (-val) % HASH_SIZE : val % HASH_SIZE, count = 0;
+    node *p = hashmap[idx];
+    while (p->next != NULL) {
+        p = p->next;
+        if (p->val == val) {
+            (p->count)++;
+            return;
+        }
+    }
+    node *new = malloc(sizeof(node));
+    new->val = val;
+    new->count = 1;
+    new->next = NULL;
+    p->next = new;
+    return;
+}
+
+// 哈希表查找
+int hash_search(HashMap hashmap[], int val) {
+    int idx = val < 0 ? (-val) % HASH_SIZE : val % HASH_SIZE;
+    node *p = hashmap[idx];
+    while (p->next != NULL) {
+        p = p->next;
+        if (p->val == val) return p->count;
+    }
+    return 0;
+}
+
+int fourSumCount(int* nums1, int nums1Size, int* nums2, int nums2Size, int* nums3, int nums3Size, int* nums4, int nums4Size){
+    // 初始化哈希表
+    HashMap hashmap[HASH_SIZE];
+    for (int i = 0; i < HASH_SIZE; i++) {
+        hashmap[i] = malloc(sizeof(node));
+        hashmap[i]->next = NULL;
+    }
+    
+    // 统计两个数组元素之和的负值和出现的次数，放到哈希表中
+    int count = 0, num;
+    for (int i = 0; i < nums1Size; i++) {
+        for(int j = 0; j < nums2Size; j++) {
+            num = - nums1[i] - nums2[j];
+            hash_insert(hashmap, num);
+        }
+    }
+    
+    // 统计另外两个数组元素之和，查找哈希表中对应元素的出现次数，加入总次数
+    for (int i = 0; i < nums3Size; i++) {
+        for(int j = 0; j < nums4Size; j++) {
+            num = nums3[i] + nums4[j];
+            count += hash_search(hashmap, num);
+        }
+    }
+    return count;
+}
+```
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>

problems/0455.分发饼干.md

@@ -229,7 +229,7 @@ func findContentChildren(g []int, s []int) int {
 ### Rust
 
 ```rust
-pub fn find_content_children(mut children: Vec<i32>, mut cookie: Vec<i32>) -> i32 {
+pub fn find_content_children(mut children: Vec<i32>, mut cookies: Vec<i32>) -> i32 {
     children.sort();
     cookies.sort();
 

problems/0459.重复的子字符串.md

@@ -682,7 +682,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 前缀表不减一
 public bool RepeatedSubstringPattern(string s)
 {

problems/0474.一和零.md

@@ -533,6 +533,67 @@ impl Solution {
     }
 }
 ```
+## C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int findMaxForm(char** strs, int strsSize, int m, int n) {
+    int dp[m + 1][n + 1];
+    memset(dp, 0, sizeof (int ) * (m + 1) * (n + 1));
+    for(int i = 0; i < strsSize; i++){
+        // 统计0和1的数量
+        int count0 = 0;
+        int count1 = 0;
+        char *str = strs[i];
+        while (*str != '\0'){
+            if(*str == '0'){
+                count0++;
+            } else{
+                count1++;
+            }
+            str++;
+        }
+        for(int j = m; j >= count0; j--){
+            for(int k = n; k >= count1; k--){
+                dp[j][k] = max(dp[j][k], dp[j - count0][k - count1] + 1);
+            }
+        }
+    }
+    return dp[m][n];
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int FindMaxForm(string[] strs, int m, int n)
+    {
+        int[,] dp = new int[m + 1, n + 1];
+        foreach (string str in strs)
+        {
+            int zero = 0, one = 0;
+            foreach (char c in str)
+            {
+                if (c == '0') zero++;
+                else one++;
+            }
+            for (int i = m; i >= zero; i--)
+            {
+                for (int j = n; j >= one; j--)
+                {
+                    dp[i, j] = Math.Max(dp[i, j], dp[i - zero, j - one] + 1);
+                }
+            }
+        }
+        return dp[m, n];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0494.目标和.md

@@ -585,6 +585,70 @@ impl Solution {
     }
 }
 ```
+## C
+
+```c
+int getSum(int * nums, int numsSize){
+    int sum = 0;
+    for(int i = 0; i < numsSize; i++){
+        sum += nums[i];
+    }
+    return sum;
+}
+
+int findTargetSumWays(int* nums, int numsSize, int target) {
+    int sum = getSum(nums, numsSize);
+    int diff = sum - target;
+    // 两种情况不满足
+    if(diff < 0 || diff % 2 != 0){
+        return 0;
+    }
+    int bagSize = diff / 2;
+    int dp[numsSize + 1][bagSize + 1];
+    dp[0][0] = 1;
+    for(int i = 1; i <= numsSize; i++){
+        int num = nums[i - 1];
+        for(int j = 0; j <= bagSize; j++){
+            dp[i][j] = dp[i - 1][j];
+            if(j >= num){
+                dp[i][j] += dp[i - 1][j - num];
+            }
+        }
+    }
+    return dp[numsSize][bagSize];
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int FindTargetSumWays(int[] nums, int target)
+    {
+        int sum = 0;
+        foreach (int num in nums)
+        {
+            sum += num;
+        }
+        if (Math.Abs(target) > sum) return 0;
+        if ((sum + target) % 2 == 1) return 0;
+        int bagSize = (sum + target) / 2;
+        int[] dp = new int[bagSize + 1];
+        dp[0] = 1;
+        for (int i = 0; i < nums.Length; i++)
+        {
+            for (int j = bagSize; j >= nums[i]; j--)
+            {
+                dp[j] += dp[j - nums[i]];
+            }
+        }
+        return dp[bagSize];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/0496.下一个更大元素I.md

@@ -256,6 +256,7 @@ class Solution {
 ### Python3
 
 ```python
+# 版本一
 class Solution:
     def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
         result = [-1]*len(nums1)
@@ -273,6 +274,26 @@ class Solution:
                     stack.pop()                 
                 stack.append(i)
         return result
+
+# 版本二
+class Solution:
+    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
+        stack = []
+        # 创建答案数组
+        ans = [-1] * len(nums1)
+        for i in range(len(nums2)):
+            while len(stack) > 0 and nums2[i] > nums2[stack[-1]]:
+                # 判断 num1 是否有 nums2[stack[-1]]。如果没有这个判断会出现指针异常
+                if nums2[stack[-1]] in nums1:
+                    # 锁定 num1 检索的 index
+                    index = nums1.index(nums2[stack[-1]])
+                    # 更新答案数组
+                    ans[index] = nums2[i]
+                # 弹出小元素
+                # 这个代码一定要放在 if 外面。否则单调栈的逻辑就不成立了
+                stack.pop()
+            stack.append(i)
+        return ans
 ```
 
 ### Go

problems/0501.二叉搜索树中的众数.md

@@ -1010,7 +1010,7 @@ pub fn find_mode(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
     }
 ```
 ### C#
-```C#
+```csharp
 // 递归 
 public class Solution
 {

problems/0503.下一个更大元素II.md

@@ -170,7 +170,6 @@ class Solution {
 ### Python: 
 
 ```python
-# 方法 1:
 class Solution:
     def nextGreaterElements(self, nums: List[int]) -> List[int]:
         dp = [-1] * len(nums)
@@ -181,26 +180,6 @@ class Solution:
                     stack.pop()
             stack.append(i%len(nums))
         return dp
-
-# 方法 2:
-class Solution:
-    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
-        stack = []
-        # 创建答案数组
-        ans = [-1] * len(nums1)
-        for i in range(len(nums2)):
-            while len(stack) > 0 and nums2[i] > nums2[stack[-1]]:
-                # 判断 num1 是否有 nums2[stack[-1]]。如果没有这个判断会出现指针异常
-                if nums2[stack[-1]] in nums1:
-                    # 锁定 num1 检索的 index
-                    index = nums1.index(nums2[stack[-1]])
-                    # 更新答案数组
-                    ans[index] = nums2[i]
-                # 弹出小元素
-                # 这个代码一定要放在 if 外面。否则单调栈的逻辑就不成立了
-                stack.pop()
-            stack.append(i)
-        return ans
 ```
 ### Go:
 

problems/0509.斐波那契数.md

@@ -439,7 +439,7 @@ object Solution {
 
 动态规划:
 
-```c#
+```csharp
 public class Solution
 {
     public int Fib(int n)
@@ -459,7 +459,7 @@ public class Solution
 
 递归:
 
-```c#	
+```csharp	
 public class Solution
 {
     public int Fib(int n)

problems/0513.找树左下角的值.md

@@ -685,7 +685,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 //递归
 int maxDepth = -1;
 int res = 0;
@@ -716,9 +716,55 @@ public void Traversal(TreeNode root, int depth)
     return;
 }
 ```
+```csharp
+/*
+ * @lc app=leetcode id=513 lang=csharp
+ * 迭代法
+ * [513] Find Bottom Left Tree Value
+ */
+
+// @lc code=start
+public class Solution
+{
+    public int FindBottomLeftValue(TreeNode root)
+    {
+        Queue<TreeNode> que = new Queue<TreeNode>();
+
+        if (root != null)
+        {
+            que.Enqueue(root);
+        }
+        
+        int ans = 0;
+        while (que.Count != 0)
+        {
+           
+            int size = que.Count;
+            for (var i = 0; i < size; i++)
+            {
+                var curNode = que.Peek();
+                que.Dequeue();
+                if(i == 0){
+                    ans = curNode.val;
+                }
+                if (curNode.left != null)
+                {
+                    que.Enqueue(curNode.left);
+                }
+                if (curNode.right != null)
+                {
+                    que.Enqueue(curNode.right);
+                }
+            }
+
+        }
+        return ans;
+    }
+}
+// @lc code=end
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0518.零钱兑换II.md

@@ -224,20 +224,26 @@ class Solution {
 // 二维dp数组版本，方便理解
 class Solution {
     public int change(int amount, int[] coins) {
-        int[][] dp = new int[coins.length][amount + 1];
+        int[][] dp = new int[coins.length][amount+1];
-        // 只有一种硬币的情况
+
-        for (int i = 0; i <= amount; i += coins[0]) {
+        // 初始化边界值
-            dp[0][i] = 1;
+        for(int i = 0; i < coins.length; i++){
+            // 第一列的初始值为1
+            dp[i][0] = 1;
         }
-        for (int i = 1; i < coins.length; i++) {
+        for(int j = coins[0]; j <= amount; j++){
-            for (int j = 0; j <= amount; j++) {
+            // 初始化第一行
-                // 第i种硬币使用0~k次，求和
+            dp[0][j] += dp[0][j-coins[0]];
-                for (int k = 0; k * coins[i] <= j; k++) {
+        }
-                    dp[i][j] += dp[i - 1][j - k * coins[i]];
+        
-                }
+        for(int i = 1; i < coins.length; i++){
+            for(int j = 1; j <= amount; j++){
+                if(j < coins[i]) dp[i][j] = dp[i-1][j];
+                else dp[i][j] = dp[i][j-coins[i]] + dp[i-1][j];
             }
         }
-        return dp[coins.length - 1][amount];
+
+        return dp[coins.length-1][amount];
     }
 }
 ```
@@ -347,8 +353,50 @@ object Solution {
   }
 }
 ```
+## C
+
+```c
+int change(int amount, int* coins, int coinsSize) {
+    int dp[amount + 1];
+    memset(dp, 0, sizeof (dp));
+    dp[0] = 1;
+    // 遍历物品
+    for(int i = 0; i < coinsSize; i++){
+        // 遍历背包
+        for(int j = coins[i]; j <= amount; j++){
+            dp[j] += dp[j - coins[i]];
+        }
+    }
+    return dp[amount];
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int Change(int amount, int[] coins)
+    {
+        int[] dp = new int[amount + 1];
+        dp[0] = 1;
+        for (int i = 0; i < coins.Length; i++)
+        {
+            for (int j = coins[i]; j <= amount; j++)
+            {
+                if (j >= coins[i])
+                    dp[j] += dp[j - coins[i]];
+            }
+        }
+        return dp[amount];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0530.二叉搜索树的最小绝对差.md

@@ -648,7 +648,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public class Solution
 {

problems/0538.把二叉搜索树转换为累加树.md

@@ -530,7 +530,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public class Solution
 {

problems/0617.合并二叉树.md

@@ -789,7 +789,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public TreeNode MergeTrees(TreeNode root1, TreeNode root2)
 {
     if (root1 == null) return root2;

problems/0647.回文子串.md

@@ -397,6 +397,7 @@ class Solution:
 ```
 
 ### Go：
+> 动态规划：
 
 ```Go
 func countSubstrings(s string) int {
@@ -422,6 +423,47 @@ func countSubstrings(s string) int {
     return res
 }
 ```
+> 动态规划：简洁版
+```Go
+func countSubstrings(s string) int {
+	res := 0
+	dp := make([][]bool, len(s))
+	for i := 0; i < len(s); i++ {
+		dp[i] = make([]bool, len(s))
+	}
+
+	for i := len(s) - 1; i >= 0; i-- {
+		for j := i; j < len(s); j++ {
+			if s[i] == s[j] && (j-i <= 1 || dp[i+1][j-1]) {
+				res++
+				dp[i][j] = true
+			}
+		}
+	}
+	return res
+}
+```
+
+> 双指针法：
+```Go
+func countSubstrings(s string) int {
+	extend := func(i, j int) int {
+		res := 0
+		for i >= 0 && j < len(s) && s[i] == s[j] {
+			i --
+			j ++
+			res ++
+		}
+		return res
+	}
+	res := 0
+	for i := 0; i < len(s); i++ {
+		res += extend(i, i)  // 以i为中心
+		res += extend(i, i+1) // 以i和i+1为中心
+	}
+	return res
+}
+```
 
 ### Javascript：
 

problems/0654.最大二叉树.md

@@ -583,7 +583,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 public TreeNode ConstructMaximumBinaryTree(int[] nums)
 {
     if (nums.Length == 0) return null;

problems/0669.修剪二叉搜索树.md

@@ -79,7 +79,7 @@ public:
 
 代码如下：
 
-```
+```cpp
 TreeNode* trimBST(TreeNode* root, int low, int high)
 ```
 
@@ -87,7 +87,7 @@ TreeNode* trimBST(TreeNode* root, int low, int high)
 
 修剪的操作并不是在终止条件上进行的，所以就是遇到空节点返回就可以了。
 
-```
+```cpp
 if (root == nullptr ) return nullptr;
 ```
 
@@ -97,7 +97,7 @@ if (root == nullptr ) return nullptr;
 
 代码如下：
 
-```
+```cpp
 if (root->val < low) {
     TreeNode* right = trimBST(root->right, low, high); // 寻找符合区间[low, high]的节点
     return right;
@@ -108,7 +108,7 @@ if (root->val < low) {
 
 代码如下：
 
-```
+```cpp
 if (root->val > high) {
     TreeNode* left = trimBST(root->left, low, high); // 寻找符合区间[low, high]的节点
     return left;
@@ -119,7 +119,7 @@ if (root->val > high) {
 
 最后返回root节点，代码如下：
 
-```
+```cpp
 root->left = trimBST(root->left, low, high); // root->left接入符合条件的左孩子
 root->right = trimBST(root->right, low, high); // root->right接入符合条件的右孩子
 return root;
@@ -133,7 +133,7 @@ return root;
 
 如下代码相当于把节点0的右孩子（节点2）返回给上一层，
 
-```
+```cpp
 if (root->val < low) {
     TreeNode* right = trimBST(root->right, low, high); // 寻找符合区间[low, high]的节点
     return right;
@@ -142,7 +142,7 @@ if (root->val < low) {
 
 然后如下代码相当于用节点3的左孩子 把下一层返回的 节点0的右孩子（节点2） 接住。
 
-```
+``` cpp
 root->left = trimBST(root->left, low, high);
 ```
 
@@ -568,7 +568,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public TreeNode TrimBST(TreeNode root, int low, int high)
 {

problems/0674.最长连续递增序列.md

@@ -425,6 +425,57 @@ function findLengthOfLCIS(nums: number[]): number {
 };
 ```
 
+### C：
+
+> 动态规划：
+
+```c
+int findLengthOfLCIS(int* nums, int numsSize) {
+    if(numsSize == 0){
+        return 0;
+    }
+    int dp[numsSize];
+    for(int i = 0; i < numsSize; i++){
+        dp[i] = 1;
+    }
+    int result = 1;
+    for (int i = 1; i < numsSize; ++i) {
+        if(nums[i] > nums[i - 1]){
+            dp[i] = dp[i - 1] + 1;
+        }
+        if(dp[i] > result){
+            result = dp[i];
+        }
+    }
+    return result;
+}
+```
+
+
+
+> 贪心:
+
+```c
+int findLengthOfLCIS(int* nums, int numsSize) {
+    int result = 1;
+    int count = 1;
+    if(numsSize == 0){
+        return result;
+    }
+    for (int i = 1; i < numsSize; ++i) {
+        if(nums[i] > nums[i - 1]){
+            count++;
+        } else{
+            count = 1;
+        }
+        if(count > result){
+            result = count;
+        }
+    }
+    return result;
+}
+```
+
 
 
 
@@ -432,4 +483,3 @@ function findLengthOfLCIS(nums: number[]): number {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0685.冗余连接II.md

@@ -69,7 +69,7 @@ edges[2][0] = 2，edges[2][1] = 3，
 
 搞清楚之后，我们如何统计入度呢？ 
 
-即 edges[i][1] 表示的节点都是 箭头指向的节点，即这个几点有一个入度！ （如果想统计出度，那么就是 edges[i][0]）。
+即 edges[i][1] 表示的节点都是 箭头指向的节点，即这个节点有一个入度！ （如果想统计出度，那么就是 edges[i][0]）。
 
 所以，统计入度的代码如下：
 
@@ -81,7 +81,7 @@ for (int i = 0; i < n; i++) {
 }
 ```
 
-前两种入度为2的情况，一定是删除指向入度为2的节点的两条边其中的一条，如果删了一条，判断这个图是一个树，那么这条边就是答案，同时注意要从后向前遍历，因为如果两天边删哪一条都可以成为树，就删最后那一条。
+前两种入度为2的情况，一定是删除指向入度为2的节点的两条边其中的一条，如果删了一条，判断这个图是一个树，那么这条边就是答案，同时注意要从后向前遍历，因为如果两条边删哪一条都可以成为树，就删最后那一条。
 
 代码如下：
 
@@ -108,7 +108,7 @@ if (vec.size() > 0) {
 
 可以定义一个函数，代码如下：
 
-```
+```cpp
 // 在有向图里找到删除的那条边，使其变成树，返回值就是要删除的边
 vector<int> getRemoveEdge(const vector<vector<int>>& edges)
 ```

problems/0695.岛屿的最大面积.md

@@ -428,6 +428,146 @@ var maxAreaOfIsland = function (grid) {
 };
 ```
 
+### Go
+
+dsf: 版本一
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				// 第一种写法，重制 count，必定有 1 个
+				count = 1
+				dfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// 第一种写法
+func dfs(grid [][]int, visited [][]bool, i, j int) {
+	visited[i][j] = true // 标记已访问，循环中未标记会导致重复
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+			continue
+		}
+		if grid[x][y] == 1 && !visited[x][y] {
+			count++
+			dfs(grid, visited, x, y)
+		}
+	}
+}
+```
+
+dfs：版本二
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				// 第二种写法
+				count = 0
+				dfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// 第二种写法
+func dfs(grid [][]int, visited [][]bool, i, j int) {
+	if visited[i][j] || grid[i][j] == 0 {
+		return
+	}
+	visited[i][j] = true
+	count++
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+			continue
+		}
+		dfs(grid, visited, x, y)
+	}
+}
+```
+
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				count = 0
+				bfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// bfs
+func bfs(grid [][]int, visited [][]bool, i, j int) {
+	visited[i][j] = true
+	count++
+	queue := [][2]int{{i, j}}
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+				continue
+			}
+			if grid[x][y] == 1 && !visited[x][y] {
+				count++
+				queue = append(queue, [2]int{x, y})
+				visited[x][y] = true
+			}
+		}
+	}
+}
+```
 
 ### Rust
 

problems/0700.二叉搜索树中的搜索.md

@@ -465,7 +465,7 @@ impl Solution {
 }
 ```
 ### C#
-```C#
+```csharp
 // 递归
 public TreeNode SearchBST(TreeNode root, int val)
 {

problems/0701.二叉搜索树中的插入操作.md

@@ -59,7 +59,7 @@
 
 代码如下：
 
-```
+```cpp
 TreeNode* insertIntoBST(TreeNode* root, int val)
 ```
 
@@ -69,7 +69,7 @@ TreeNode* insertIntoBST(TreeNode* root, int val)
 
 代码如下：
 
-```
+```cpp
 if (root == NULL) {
     TreeNode* node = new TreeNode(val);
     return node;
@@ -88,7 +88,7 @@ if (root == NULL) {
 
 代码如下：
 
-```
+```cpp
 if (root->val > val) root->left = insertIntoBST(root->left, val);
 if (root->val < val) root->right = insertIntoBST(root->right, val);
 return root;
@@ -120,7 +120,7 @@ public:
 
 那么递归函数定义如下：
 
-```
+```cpp
 TreeNode* parent; // 记录遍历节点的父节点
 void traversal(TreeNode* cur, int val)
 ```

problems/0707.设计链表.md

@@ -1486,7 +1486,7 @@ impl MyLinkedList {
 ```
 
 ### C#
-```C#
+```csharp
 class ListNode
 {
     public int val;

problems/0714.买卖股票的最佳时机含手续费（动态规划）.md

@@ -247,7 +247,29 @@ function maxProfit(prices: number[], fee: number): number {
 };
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+// dp[i][0] 表示第i天持有股票所省最多现金。
+// dp[i][1] 表示第i天不持有股票所得最多现金
+int maxProfit(int* prices, int pricesSize, int fee) {
+    int dp[pricesSize][2];
+    dp[0][0] = -prices[0];
+    dp[0][1] = 0;
+    for (int i = 1; i < pricesSize; ++i) {
+        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 dp[pricesSize - 1][1];
+}
+```
+
+
+
 ### Rust:
+
 **贪心**
 
 ```Rust
@@ -304,3 +326,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0718.最长重复子数组.md

@@ -560,10 +560,30 @@ impl Solution {
 }
 ```
 
+### C:
+
+```c
+int findLength(int* nums1, int nums1Size, int* nums2, int nums2Size) {
+    int dp[nums1Size + 1][nums2Size + 1];
+    memset(dp, 0, sizeof(dp));
+    int result = 0;
+    for (int i = 1; i <= nums1Size; ++i) {
+        for (int j = 1; j <= nums2Size; ++j) {
+            if(nums1[i - 1] == nums2[j - 1]){
+                dp[i][j] = dp[i - 1][j - 1] + 1;
+            }
+            if(dp[i][j] > result){
+                result = dp[i][j];
+            }
+        }
+    }
+    return result;
+}
+```
+
 
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0738.单调递增的数字.md

@@ -392,9 +392,58 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+int monotoneIncreasingDigits(int n) {
+    char str[11];
+    // 将数字转换为字符串
+    sprintf(str, "%d", n);
+    int len = strlen(str);
+    int flag = strlen(str);
+    for(int i = len - 1; i > 0; i--){
+        if(str[i] < str[i - 1]){
+            str[i - 1]--;
+            flag = i;
+        }
+    }
+    for(int i = flag; i < len; i++){
+        str[i] = '9';
+    }
+    // 字符串转数字
+    return atoi(str);
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public int MonotoneIncreasingDigits(int n)
+    {
+        char[] s = n.ToString().ToCharArray();
+        int flag = s.Length;
+        for (int i = s.Length - 1; i > 0; i--)
+        {
+            if (s[i - 1] > s[i])
+            {
+                flag = i;
+                s[i - 1]--;
+            }
+        }
+        for (int i = flag; i < s.Length; i++)
+        {
+            s[i] = '9';
+        }
+        return int.Parse(new string(s));
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0746.使用最小花费爬楼梯.md

@@ -500,7 +500,7 @@ object Solution {
 
 ### C#
 
-```c#
+```csharp
 public class Solution
 {
     public int MinCostClimbingStairs(int[] cost)

problems/0763.划分字母区间.md

@@ -404,9 +404,65 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int* partitionLabels(char* s, int* returnSize) {
+    // 记录每个字符最远出现的位置
+    int last[26] = {0};
+    int len = strlen(s);
+    for (int i = 0; i < len; ++i) {
+        last[s[i] - 'a'] = i;
+    }
+    int left = 0, right = 0;
+    int * partition = malloc(sizeof (int ) * len);
+    // 初始化值
+    *returnSize = 0;
+    for(int i = 0; i < len; i++){
+        right = max(right, last[s[i] - 'a']);
+        // 到达最远位置，加入答案，并且更新左边下标
+        if(i == right){
+            partition[(*returnSize)++] = right - left + 1;
+            left = i + 1;
+        }
+    }
+    return partition;
+}
+```
+
+
+
+### C#
+
+```csharp
+public class Solution
+{
+    public IList<int> PartitionLabels(string s)
+    {
+        int[] location = new int[27];
+        for (int i = 0; i < s.Length; i++)
+        {
+            location[s[i] - 'a'] = i;
+        }
+        List<int> res = new List<int>();
+        int left = 0, right = 0;
+        for (int i = 0; i < s.Length; i++)
+        {
+            right = Math.Max(right, location[s[i] - 'a']);
+            if (i == right)
+            {
+                res.Add(right - left + 1);
+                left = i + 1;
+            }
+        }
+        return res;
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/0827.最大人工岛.md

@@ -348,6 +348,162 @@ class Solution:
 
 ```
 
+
+### Go
+
+```go
+func largestIsland(grid [][]int) int {
+	dir := [][]int{{0, 1}, {1, 0}, {-1, 0}, {0, -1}}
+	n := len(grid)
+	m := len(grid[0])
+	area := 0
+	visited := make([][]bool, n)
+	for i := 0; i < n; i++ {
+		visited[i] = make([]bool, m)
+	}
+	gridNum := make(map[int]int, 0) // 记录每一个岛屿的面积
+	mark := 2                       // 记录每个岛屿的编号
+	isAllGrid := true
+	res := 0 // 标记是否整个地图都是陆地
+
+	var dfs func(grid [][]int, visited [][]bool, x, y, mark int)
+	dfs = func(grid [][]int, visited [][]bool, x, y, mark int) {
+		// 终止条件：访问过的节点 或者 遇到海水
+		if visited[x][y] || grid[x][y] == 0 {
+			return
+		}
+		visited[x][y] = true // 标记访问过
+		grid[x][y] = mark    // 给陆地标记新标签
+		area++
+		for i := 0; i < 4; i++ {
+			nextX := x + dir[i][0]
+			nextY := y + dir[i][1]
+			if nextX < 0 || nextX >= len(grid) || nextY < 0 || nextY >= len(grid[0]) {
+				continue
+			}
+			dfs(grid, visited, nextX, nextY, mark)
+		}
+	}
+
+	for i := 0; i < n; i++ {
+		for j := 0; j < m; j++ {
+			if grid[i][j] == 0 {
+				isAllGrid = false
+			}
+			if !visited[i][j] && grid[i][j] == 1 {
+				area = 0
+				dfs(grid, visited, i, j, mark) // 将与其链接的陆地都标记上 true
+				gridNum[mark] = area           // 记录每一个岛屿的面积
+				mark++                         // 更新下一个岛屿编号
+			}
+		}
+	}
+	if isAllGrid {
+		return n * m
+	}
+	// 根据添加陆地的位置，计算周边岛屿面积之和
+	visitedGrid := make(map[int]struct{}) // 标记访问过的岛屿
+	for i := 0; i < n; i++ {
+		for j := 0; j < m; j++ {
+			count := 1                           // 记录连接之后的岛屿数量
+			visitedGrid = make(map[int]struct{}) // 每次使用时，清空
+			if grid[i][j] == 0 {
+				for k := 0; k < 4; k++ {
+					// 计算相邻坐标
+					nearI := i + dir[k][0]
+					nearJ := j + dir[k][1]
+					if nearI < 0 || nearI >= len(grid) || nearJ < 0 || nearJ >= len(grid[0]) {
+						continue
+					}
+					// 添加过的岛屿不要重复添加
+					if _, ok := visitedGrid[grid[nearI][nearJ]]; ok {
+						continue
+					}
+					// 把相邻四面的岛屿数量加起来
+					count += gridNum[grid[nearI][nearJ]]
+					// 标记该岛屿已经添加过
+					visitedGrid[grid[nearI][nearJ]] = struct{}{}
+				}
+			}
+			res = max827(res, count)
+		}
+	}
+	return res
+}
+
+func max827(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+```
+
+
+### JavaScript
+
+```JavaScript
+
+var largestIsland = function(grid) {
+let res = 0;
+const m = grid.length;
+const n = grid[0].length;
+const tag = new Array(n).fill().map(_ => new Array(m).fill(0));
+const area = new Map();
+const dir = [[0,1],[0,-1],[1,0],[-1,0]];
+const dfs = (grid,tag,x,y,mark) => {
+    let res = 1;
+    tag[x][y] = mark;
+    for(let i = 0; i < dir.length; i++) {
+        let nextX = x + dir[i][0];
+        let nextY = y + dir[i][1];
+        if(nextX < 0 || nextX >= m || nextY < 0 || nextY >= n) {
+            continue;
+        }
+        if(grid[nextX][nextY] === 1 && tag[nextX][nextY] === 0) {
+            res += dfs(grid,tag,nextX,nextY,mark);
+        }
+    }
+    return res;
+}
+let mark = 2;
+//将岛屿用mark标记
+for(let i = 0; i < m; i++) {      
+    for(let j = 0; j < n; j++) {
+        if(grid[i][j] === 1 && tag[i][j] === 0) {
+            area.set(mark,dfs(grid,tag,i,j,mark));
+            res = Math.max(res,area.get(mark));
+            mark++;
+        }
+    }
+}
+//将一个非岛屿格子变为岛屿
+for(let i = 0; i < m; i++) {
+    for(let j = 0; j < n; j++) {
+        if(grid[i][j] === 0) {
+            let z = 1;
+            const connected = new Set();
+            for(let k = 0; k < dir.length; k++) {
+                let nextX = i + dir[k][0];
+                let nextY = j + dir[k][1];
+                if(nextX < 0 || nextX >= m || nextY < 0 || nextY >= n || tag[nextX][nextY] === 0 || connected.has(tag[nextX][nextY])) {
+                    continue;
+                }
+                z += area.get(tag[nextX][nextY]);
+                connected.add(tag[nextX][nextY]);
+            }
+            res = Math.max(res,z);
+        }
+    }
+}
+return res;
+}; 
+
+
+```
+
+
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>

problems/0968.监控二叉树.md

@@ -369,8 +369,44 @@ class Solution {
 }
 ```
 
+简化分支版本：
+
+```java
+class Solution {
+    static int ans;
+    public int minCameraCover(TreeNode root) {
+        ans = 0; // 初始化
+        if(f(root) == 0) ans ++;
+        return ans;
+    }
+    // 定义 f 函数有三种返回值情况
+    // 0：表示 x 节点没有被相机监控，只能依靠父节点放相机
+    // 1：表示 x 节点被相机监控，但相机不是放在自身节点上
+    // 2：表示 x 节点被相机监控，但相机放在自身节点上
+    public static int f(TreeNode x) {
+        if(x == null) return 1; // 空树认为被监控，但没有相机
+        // 左右递归到最深处
+        int l = f(x.left);
+        int r = f(x.right);
+        // 有任意一个子节点为空，就需要当前节点放相机，不然以后没机会
+        if(l == 0 || r == 0) {
+            ans ++; // 放相机
+            return 2;
+        }
+        // 贪心策略，左右子树都被监控，且没有监控到当前节点，
+        // 那么最有利的情况就是将相机放置在当前节点父节点上，
+        // 因为这样能多监控可能的子树节点和父父节点
+        if(l == 1 && r == 1) return 0;
+        // 剩下情况就是左右子树有可能为 2，即当前节点被监控
+        return 1; 
+    }
+}
+```
+
+
 
 ### Python
+
 贪心（版本一）
 ```python
 class Solution:
@@ -726,10 +762,34 @@ impl Solution {
     }
 }
 
+```
+### C#
+```csharp
+public class Solution
+{
+    public int res = 0;
+    public int MinCameraCover(TreeNode root)
+    {
+        if (Traversal(root) == 0) res++;
+        return res;
+    }
+    public int Traversal(TreeNode cur)
+    {
+        if (cur == null) return 2;
+        int left = Traversal(cur.left);
+        int right = Traversal(cur.right);
+        if (left == 2 && right == 2) return 0;
+        else if (left == 0 || right == 0)
+        {
+            res++;
+            return 1;
+        }
+        else return 2;
+    }
+}
 ```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/1002.查找常用字符.md

@@ -327,37 +327,45 @@ var commonChars = function(words) {
 ### GO
 
 ```golang
-func commonChars(words []string) []string {
+func commonChars(A []string) []string {
-    length:=len(words)
+	var result []string
-    fre:=make([][]int,0)//统计每个字符串的词频
+	if len(A) == 0 {
-    res:=make([]string,0)
+		return result
-    //统计词频
+	}
-    for i:=0;i<length;i++{
+
-        var row [26]int//存放该字符串的词频
+	hash := make([]int, 26)  // 用来统计所有字符串里字符出现的最小频率
-        for j:=0;j<len(words[i]);j++{
+	for _, c := range A[0] { // 用第一个字符串给hash初始化
-            row[words[i][j]-97]++
+		hash[c-'a']++
-        }
+	}
-        fre=append(fre,row[:])
+
-    }
+	for i := 1; i < len(A); i++ {
-    //查找一列的最小值
+		hashOtherStr := make([]int, 26) // 统计除第一个字符串外字符的出现频率
-    for j:=0;j<len(fre[0]);j++{
+		for _, c := range A[i] {
-        pre:=fre[0][j]
+			hashOtherStr[c-'a']++
-        for i:=0;i<len(fre);i++{
+		}
-            pre=min(pre,fre[i][j])
+		// 更新hash，保证hash里统计26个字符在所有字符串里出现的最小次数
-        }
+		for k := 0; k < 26; k++ {
-        //将该字符添加到结果集（按照次数）
+			hash[k] = min(hash[k], hashOtherStr[k])
-        tmpString:=string(j+97)
+		}
-        for i:=0;i<pre;i++{
+	}
-            res=append(res,tmpString)
+
-        }
+	// 将hash统计的字符次数，转成输出形式
-    }
+	for i := 0; i < 26; i++ {
-    return res
+		for hash[i] > 0 {
+			s := string('a' + i) // rune -> string
+			result = append(result, s)
+			hash[i]--
+		}
+	}
+
+	return result
 }
-func min(a,b int)int{
+
-    if a>b{
+func min(a, b int) int {
-        return b
+	if a < b {
-    }
+		return a
-    return a
+	}
+	return b
 }
 ```
 

problems/1020.飞地的数量.md

@@ -491,6 +491,120 @@ class Solution:
         return ans
 ```
 
+### Go
+
+dfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func numEnclaves(grid [][]int) int {
+	rows, cols := len(grid), len(grid[0])
+	// 行
+	for i := range grid[0] {
+		if grid[0][i] == 1 {
+			dfs(grid, 0, i)
+		}
+		if grid[rows-1][i] == 1 {
+			dfs(grid, rows-1, i)
+		}
+	}
+	// 列
+	for j := range grid {
+		if grid[j][0] == 1 {
+			dfs(grid, j, 0)
+		}
+		if grid[j][cols-1] == 1 {
+			dfs(grid, j, cols-1)
+		}
+	}
+	count = 0
+	for i := range grid {
+		for j := range grid[0] {
+			if grid[i][j] == 1 {
+				dfs(grid, i, j)
+			}
+		}
+	}
+	return count
+}
+
+func dfs(grid [][]int, i, j int) {
+	grid[i][j] = 0
+	count++
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+			continue
+		}
+		if grid[x][y] == 1 {
+			dfs(grid, x, y)
+		}
+	}
+}
+```
+
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func numEnclaves(grid [][]int) int {
+	rows, cols := len(grid), len(grid[0])
+	// 行
+	for i := range grid[0] {
+		if grid[0][i] == 1 {
+			bfs(grid, 0, i)
+		}
+		if grid[rows-1][i] == 1 {
+			bfs(grid, rows-1, i)
+		}
+	}
+	// 列
+	for j := range grid {
+		if grid[j][0] == 1 {
+			bfs(grid, j, 0)
+		}
+		if grid[j][cols-1] == 1 {
+			bfs(grid, j, cols-1)
+		}
+	}
+	count = 0
+	for i := range grid {
+		for j := range grid[0] {
+			if grid[i][j] == 1 {
+				bfs(grid, i, j)
+			}
+		}
+	}
+	return count
+}
+
+func bfs(grid [][]int, i, j int) {
+	queue := [][]int{}
+	queue = append(queue, []int{i, j})
+	grid[i][j] = 0
+	count++
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+				continue
+			}
+			if grid[x][y] == 1 {
+				count++
+				queue = append(queue, []int{x, y})
+				grid[x][y] = 0
+			}
+		}
+	}
+}
+```
+
 ### Rust
 
 dfs:

problems/1049.最后一块石头的重量II.md

@@ -472,6 +472,30 @@ impl Solution {
     }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public int LastStoneWeightII(int[] stones)
+    {
+        int[] dp = new int[15001];
+        int sum = 0;
+        foreach (int stone in stones)
+        {
+            sum += stone;
+        }
+        int target = sum / 2;
+        for (int i = 0; i < stones.Length; i++)
+        {
+            for (int j = target; j >= stones[i]; j--)
+            {
+                dp[j] = Math.Max(dp[j], dp[j - stones[i]] + stones[i]);
+            }
+        }
+        return sum - 2 * dp[target];
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/1143.最长公共子序列.md

@@ -376,10 +376,32 @@ impl Solution {
 }
 ```
 
+### C:
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+int longestCommonSubsequence(char* text1, char* text2) {
+    int text1Len = strlen(text1);
+    int text2Len = strlen(text2);
+    int dp[text1Len + 1][text2Len + 1];
+    memset(dp, 0, sizeof (dp));
+    for (int i = 1; i <= text1Len; ++i) {
+        for (int j = 1; j <= text2Len; ++j) {
+            if(text1[i - 1] == text2[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[text1Len][text2Len];
+}
+```
+
 
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-

problems/1971.寻找图中是否存在路径.md

@@ -8,26 +8,24 @@
 
 [题目链接](https://leetcode.cn/problems/find-if-path-exists-in-graph/)
 
-有一个具有 n个顶点的 双向 图，其中每个顶点标记从 0 到 n - 1（包含 0 和 n - 1）。图中的边用一个二维整数数组 edges 表示，其中 edges[i] = [ui, vi] 表示顶点 ui 和顶点 vi 之间的双向边。 每个顶点对由 最多一条 边连接，并且没有顶点存在与自身相连的边。
+有一个具有 n 个顶点的 双向 图，其中每个顶点标记从 0 到 n - 1（包含 0 和 n - 1）。图中的边用一个二维整数数组 edges 表示，其中 edges[i] = [ui, vi] 表示顶点 ui 和顶点 vi 之间的双向边。 每个顶点对由 最多一条 边连接，并且没有顶点存在与自身相连的边。
 
 请你确定是否存在从顶点 start 开始，到顶点 end 结束的 有效路径 。
 
-给你数组 edges 和整数 n、start和end，如果从 start 到 end 存在 有效路径 ，则返回 true，否则返回 false 。
+给你数组 edges 和整数 n、start 和 end，如果从 start 到 end 存在 有效路径 ，则返回 true，否则返回 false 。
-
 
 ![](https://code-thinking-1253855093.file.myqcloud.com/pics/20220705101442.png)
 
-
 提示:
 
-* 1 <= n <= 2 * 10^5
+- 1 <= n <= 2 \* 10^5
-* 0 <= edges.length <= 2 * 10^5
+- 0 <= edges.length <= 2 \* 10^5
-* edges[i].length == 2
+- edges[i].length == 2
-* 0 <= ui, vi <= n - 1
+- 0 <= ui, vi <= n - 1
-* ui != vi
+- ui != vi
-* 0 <= start, end <= n - 1
+- 0 <= start, end <= n - 1
-* 不存在双向边
+- 不存在双向边
-* 不存在指向顶点自身的边
+- 不存在指向顶点自身的边
 
 ## 思路
 
@@ -70,7 +68,7 @@ void join(int u, int v) {
 }
 ```
 
-以上模板中，只要修改 n 大小就可以，本题n不会超过2 * 10^5。
+以上模板中，只要修改 n 大小就可以，本题 n 不会超过 2 \* 10^5。
 
 并查集主要有三个功能。
 
@@ -86,7 +84,7 @@ void join(int u, int v) {
 
 此时我们就可以直接套用并查集模板。
 
-使用join(int u, int v)将每条边加入到并查集。 
+使用 join(int u, int v)将每条边加入到并查集。
 
 最后 isSame(int u, int v) 判断是否是同一个根 就可以了。
 
@@ -191,7 +189,7 @@ class Solution {
 
 ### Python：
 
-PYTHON并查集解法如下：
+PYTHON 并查集解法如下：
 
 ```PYTHON
 class Solution:
@@ -206,6 +204,85 @@ class Solution:
         return find(source) == find(destination)
 ```
 
+### Javascript：
+
+Javascript 并查集解法如下：
+
+```Javascript
+class unionF{
+    constructor(n){
+        this.count = n
+        this.roots = new Array(n).fill(0).map((item,index)=>index)
+    }
+
+    findRoot(x){
+        if(this.roots[x]!==x){
+            this.roots[x] = this.findRoot(this.roots[x])
+        }
+        return this.roots[x]
+    }
+
+    union(x,y){
+        const rx = this.findRoot(x)
+        const ry = this.findRoot(y)
+        this.roots[rx] = ry
+        this.count--
+    }
+
+    isConnected(x,y){
+        return this.findRoot(x)===this.findRoot(y)
+    }
+}
+
+var validPath = function(n, edges, source, destination) {
+    const UF = new unionF(n)
+    for(const [s,t] of edges){
+        UF.union(s,t)
+    }
+    return UF.isConnected(source,destination)
+};
+```
+
+Javascript 双向 bfs 解法如下：
+
+```Javascript
+var validPath = function(n, edges, source, destination) {
+    const graph = new Array(n).fill(0).map(()=>[])
+    for(const [s,t] of edges){
+        graph[s].push(t)
+        graph[t].push(s)
+    }
+
+    const visited = new Array(n).fill(false)
+    function bfs(start,end,graph){
+        const startq = [start]
+        const endq = [end]
+        while(startq.length&&endq.length){
+            const slen = startq.length
+            for(let i = 0;i<slen;i++){
+                const scur = startq.shift()
+                if(visited[scur]) continue
+                if(endq.includes(scur)) return true
+                visited[scur] = true
+                const neighbors = graph[scur]
+                startq.push(...neighbors)
+            }
+
+            const elen = endq.length
+            for(let i = 0;i<elen;i++){
+                const ecur = endq.shift()
+                if(visited[ecur]) continue
+                if(startq.includes(ecur)) return true
+                visited[ecur] = true
+                const neighbors = graph[ecur]
+                endq.push(...neighbors)
+            }
+        }
+        return false
+    }
+    return bfs(source,destination,graph)
+};
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">

problems/kama54.替换数字.md

@@ -56,34 +56,34 @@
 C++代码如下：
 
 ```CPP
-#include<iostream>
+#include <iostream>
 using namespace std;
 int main() {
     string s;
     while (cin >> s) {
+        int sOldIndex = s.size() - 1;
         int count = 0; // 统计数字的个数
-        int sOldSize = s.size();
         for (int i = 0; i < s.size(); i++) {
             if (s[i] >= '0' && s[i] <= '9') {
                 count++;
             }
         }
-        // 扩充字符串s的大小，也就是每个空格替换成"number"之后的大小
+        // 扩充字符串s的大小，也就是将每个数字替换成"number"之后的大小
         s.resize(s.size() + count * 5);
-        int sNewSize = s.size();
+        int sNewIndex = s.size() - 1;
-        // 从后先前将空格替换为"number"
+        // 从后往前将数字替换为"number"
-        for (int i = sNewSize - 1, j = sOldSize - 1; j < i; i--, j--) {
+        while (sOldIndex >= 0) {
-            if (s[j] > '9' || s[j] < '0') {
+            if (s[sOldIndex] >= '0' && s[sOldIndex] <= '9') {
-                s[i] = s[j];
+                s[sNewIndex--] = 'r';
+                s[sNewIndex--] = 'e';
+                s[sNewIndex--] = 'b';
+                s[sNewIndex--] = 'm';
+                s[sNewIndex--] = 'u';
+                s[sNewIndex--] = 'n';
             } else {
-                s[i] = 'r';
+                s[sNewIndex--] = s[sOldIndex];
-                s[i - 1] = 'e';
-                s[i - 2] = 'b';
-                s[i - 3] = 'm';
-                s[i - 4] = 'u';
-                s[i - 5] = 'n';
-                i -= 5;
             }
+            sOldIndex--;
         }
         cout << s << endl;       
     }
@@ -245,7 +245,60 @@ class Solution:
         return ''.join(lst)
 ```
 ### JavaScript:
+```js
+const readline = require("readline");
 
+const rl = readline.createInterface({
+    input: process.stdin,
+    output: process.stdout
+})
+
+function main() {
+    const num0 = "0".charCodeAt();
+    const num9 = "9".charCodeAt();
+    const a = "a".charCodeAt();
+    const z = "z".charCodeAt();
+    function isAZ(str) {
+        return str >= a && str <= z;
+    }
+    function isNumber(str) {
+        return str >= num0 && str <= num9;
+    }
+    rl.on("line", (input) => {
+        let n = 0;
+        for (let i = 0; i < input.length; i++) {
+            const val = input[i].charCodeAt();
+            if (isNumber(val)) {
+                n+= 6;
+            }
+            if (isAZ(val)) {
+                n++;
+            }
+        }
+        const ans = new Array(n).fill(0);
+        let index = input.length - 1;
+        for (let i = n - 1; i >= 0; i--) {
+            const val = input[index].charCodeAt();
+            if (isAZ(val)) {
+                ans[i] = input[index];
+            }
+            if (isNumber(val)) {
+                ans[i] = "r";
+                ans[i - 1] = "e";
+                ans[i - 2] = "b";
+                ans[i - 3] = "m";
+                ans[i - 4] = "u";
+                ans[i - 5] = "n";
+                i -= 5;
+            }
+            index--;
+        }
+        console.log(ans.join(""));
+    })
+}
+
+main();
+```
 
 ### TypeScript：