Merge branch 'youngyangyang04:master' into master

problems/0015.三数之和.md

@@ -545,5 +545,64 @@ int** threeSum(int* nums, int numsSize, int* returnSize, int** returnColumnSizes
 }
 ```
 
+C#:
+```csharp
+public class Solution
+{
+    public IList<IList<int>> ThreeSum(int[] nums)
+    {
+        var result = new List<IList<int>>();
+
+        Array.Sort(nums);
+
+        for (int i = 0; i < nums.Length - 2; i++)
+        {
+            int n1 = nums[i];
+
+            if (n1 > 0)
+                break;
+
+            if (i > 0 && n1 == nums[i - 1])
+                continue;
+
+            int left = i + 1;
+            int right = nums.Length - 1;
+
+            while (left < right)
+            {
+                int n2 = nums[left];
+                int n3 = nums[right];
+                int sum = n1 + n2 + n3;
+
+                if (sum > 0)
+                {
+                    right--;
+                }
+                else if (sum < 0)
+                {
+                    left++;
+                }
+                else
+                {
+                    result.Add(new List<int> { n1, n2, n3 });
+
+                    while (left < right && nums[left] == n2)
+                    {
+                        left++;
+                    }
+
+                    while (left < right && nums[right] == n3)
+                    {
+                        right--;
+                    }
+                }
+            }
+        }
+
+        return result;
+    }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0018.四数之和.md

@@ -445,5 +445,67 @@ func fourSum(_ nums: [Int], _ target: Int) -> [[Int]] {
 }
 ```
 
+C#:
+```csharp
+public class Solution
+{
+    public IList<IList<int>> FourSum(int[] nums, int target)
+    {
+        var result = new List<IList<int>>();
+
+        Array.Sort(nums);
+
+        for (int i = 0; i < nums.Length - 3; i++)
+        {
+            int n1 = nums[i];
+            if (i > 0 && n1 == nums[i - 1])
+                continue;
+
+            for (int j = i + 1; j < nums.Length - 2; j++)
+            {
+                int n2 = nums[j];
+                if (j > i + 1 && n2 == nums[j - 1])
+                    continue;
+
+                int left = j + 1;
+                int right = nums.Length - 1;
+
+                while (left < right)
+                {
+                    int n3 = nums[left];
+                    int n4 = nums[right];
+                    int sum = n1 + n2 + n3 + n4;
+
+                    if (sum > target)
+                    {
+                        right--;
+                    }
+                    else if (sum < target)
+                    {
+                        left++;
+                    }
+                    else
+                    {
+                        result.Add(new List<int> { n1, n2, n3, n4 });
+
+                        while (left < right && nums[left] == n3)
+                        {
+                            left++;
+                        }
+
+                        while (left < right && nums[right] == n4)
+                        {
+                            right--;
+                        }
+                    }
+                }
+            }
+        }
+
+        return result;
+    }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0028.实现strStr.md

@@ -929,6 +929,83 @@ var strStr = function (haystack, needle) {
 };
 ```
 
+TypeScript版本：
+
+> 前缀表统一减一
+
+```typescript
+function strStr(haystack: string, needle: string): number {
+    function getNext(str: string): number[] {
+        let next: number[] = [];
+        let j: number = -1;
+        next[0] = j;
+        for (let i = 1, length = str.length; i < length; i++) {
+            while (j >= 0 && str[i] !== str[j + 1]) {
+                j = next[j];
+            }
+            if (str[i] === str[j + 1]) {
+                j++;
+            }
+            next[i] = j;
+        }
+        return next;
+    }
+    if (needle.length === 0) return 0;
+    let next: number[] = getNext(needle);
+    let j: number = -1;
+    for (let i = 0, length = haystack.length; i < length; i++) {
+        while (j >= 0 && haystack[i] !== needle[j + 1]) {
+            j = next[j];
+        }
+        if (haystack[i] === needle[j + 1]) {
+            if (j === needle.length - 2) {
+                return i - j - 1;
+            }
+            j++;
+        }
+    }
+    return -1;
+};
+```
+
+> 前缀表不减一
+
+```typescript
+// 不减一版本
+function strStr(haystack: string, needle: string): number {
+    function getNext(str: string): number[] {
+        let next: number[] = [];
+        let j: number = 0;
+        next[0] = j;
+        for (let i = 1, length = str.length; i < length; i++) {
+            while (j > 0 && str[i] !== str[j]) {
+                j = next[j - 1];
+            }
+            if (str[i] === str[j]) {
+                j++;
+            }
+            next[i] = j;
+        }
+        return next;
+    }
+    if (needle.length === 0) return 0;
+    let next: number[] = getNext(needle);
+    let j: number = 0;
+    for (let i = 0, length = haystack.length; i < length; i++) {
+        while (j > 0 && haystack[i] !== needle[j]) {
+            j = next[j - 1];
+        }
+        if (haystack[i] === needle[j]) {
+            if (j === needle.length - 1) {
+                return i - j;
+            }
+            j++;
+        }
+    }
+    return -1;
+}
+```
+
 Swift 版本
 
 > 前缀表统一减一

problems/0051.N皇后.md

@@ -346,69 +346,56 @@ class Solution {
 
 ### Go 
 ```Go
-import "strings"
-var res [][]string
-
-func isValid(board [][]string, row, col int) (res bool){
-    n := len(board)
-    for i:=0; i < row; i++ {
-        if board[i][col] == "Q" {
-            return false
-        }
-    }
-    for i := 0; i < n; i++{
-        if board[row][i] == "Q" {
-            return false
-        }
-    }
-
-    for i ,j := row, col; i >= 0 && j >=0 ; i, j = i - 1, j- 1{
-        if board[i][j] == "Q"{
-            return false
-        }
-    }
-    for i, j := row, col; i >=0 && j < n; i,j = i-1, j+1 {
-        if board[i][j] == "Q" {
-            return false
-        }
-    }
-    return true
-}
-
-func backtrack(board [][]string, row int) {
-    size := len(board)
-    if row == size{
-        temp := make([]string, size)
-        for i := 0; i<size;i++{
-            temp[i] = strings.Join(board[i],"")
-        }
-        res =append(res,temp)
-        return 
-    }
-    for col := 0; col < size; col++ {
-        if !isValid(board, row, col){
-            continue
-        }
-        board[row][col] = "Q"
-        backtrack(board, row+1)
-        board[row][col] = "."
-    }
-}
-
 func solveNQueens(n int) [][]string {
-    res = [][]string{}
+    var res [][]string
-    board := make([][]string, n)
+	chessboard := make([][]string, n)
-    for i := 0; i < n; i++{
+	for i := 0; i < n; i++ {
-        board[i] = make([]string, n)
+		chessboard[i] = make([]string, n)
-    }
+	}
-    for i := 0; i < n; i++{
+	for i := 0; i < n; i++ {
-        for j := 0; j<n;j++{
+		for j := 0; j < n; j++ {
-            board[i][j] = "."
+			chessboard[i][j] = "."
-        }
+		}
-    }
+	}
-    backtrack(board, 0)
+	var backtrack func(int)
+	backtrack = func(row int) {
+		if row == n {
+			temp := make([]string, n)
+			for i, rowStr := range chessboard {
+				temp[i] = strings.Join(rowStr, "")
+			}
+			res = append(res, temp)
+			return
+		}
+		for i := 0; i < n; i++ {
+			if isValid(n, row, i, chessboard) {
+				chessboard[row][i] = "Q"
+				backtrack(row + 1)
+				chessboard[row][i] = "."
+			}
+		}
+	}
+	backtrack(0)
+	return res
+}
 
-    return res
+func isValid(n, row, col int, chessboard [][]string) bool {
+	for i := 0; i < row; i++ {
+		if chessboard[i][col] == "Q" {
+			return false
+		}
+	}
+	for i, j := row-1, col-1; i >= 0 && j >= 0; i, j = i-1, j-1 {
+		if chessboard[i][j] == "Q" {
+			return false
+		}
+	}
+	for i, j := row-1, col+1; i >= 0 && j < n; i, j = i-1, j+1 {
+		if chessboard[i][j] == "Q" {
+			return false
+		}
+	}
+	return true
 }
 ```
 ### Javascript 

problems/0054.螺旋矩阵.md

@@ -131,7 +131,46 @@ public:
 * [59.螺旋矩阵II](https://leetcode-cn.com/problems/spiral-matrix-ii/)
 * [剑指Offer 29.顺时针打印矩阵](https://leetcode-cn.com/problems/shun-shi-zhen-da-yin-ju-zhen-lcof/)
 
+## 其他语言版本
+Python:
+```python
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        m, n = len(matrix), len(matrix[0])
+        left, right, up, down = 0, n - 1, 0, m - 1 # 定位四个方向的边界，闭区间
+        res = []
         
+        while True:
+            for i in range(left, right + 1): # 上边，从左到右
+                res.append(matrix[up][i])
+            up += 1 # 上边界下移
+
+            if len(res) >= m * n: # 判断是否已经遍历完
+                break
+            
+            for i in range(up, down + 1): # 右边，从上到下
+                res.append(matrix[i][right])
+            right -= 1 # 右边界左移
+
+            if len(res) >= m * n:
+                break
+            
+            for i in range(right, left - 1, -1): # 下边，从右到左
+                res.append(matrix[down][i])
+            down -= 1 # 下边界上移
+
+            if len(res) >= m * n:
+                break
+
+            for i in range(down, up - 1, -1): # 左边，从下到上
+                res.append(matrix[i][left])
+            left += 1 # 左边界右移
+            
+            if len(res) >= m * n:
+                break
+
+        return res
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0063.不同路径II.md

@@ -266,46 +266,33 @@ Go：
 
 ```go
 func uniquePathsWithObstacles(obstacleGrid [][]int) int {
-	m,n:= len(obstacleGrid),len(obstacleGrid[0])
+	m, n := len(obstacleGrid), len(obstacleGrid[0])
 	// 定义一个dp数组
-	dp := make([][]int,m)
+	dp := make([][]int, m)
-	for i,_ := range dp {
+	for i, _ := range dp {
-		dp[i] = make([]int,n)
+		dp[i] = make([]int, n)
 	}
-	// 初始化
+	// 初始化, 如果是障碍物, 后面的就都是0, 不用循环了
-	for i:=0;i<m;i++ {
+	for i := 0; i < m && obstacleGrid[i][0] == 0; i++ {
-		// 如果是障碍物, 后面的就都是0, 不用循环了
+		dp[i][0] = 1
-		if obstacleGrid[i][0] == 1 {
-			break
-		}
-		dp[i][0]=1
 	}
-	for i:=0;i<n;i++ {
+	for i := 0; i < n && obstacleGrid[0][i] == 0; i++ {
-		if obstacleGrid[0][i] == 1 {
+		dp[0][i] = 1
-			break
-		}
-		dp[0][i]=1
 	}
 	// dp数组推导过程
-	for i:=1;i<m;i++ {
+	for i := 1; i < m; i++ {
-		for j:=1;j<n;j++ {
+		for j := 1; j < n; j++ {
-			// 如果obstacleGrid[i][j]这个点是障碍物, 那么我们的dp[i][j]保持为0
+			// 如果obstacleGrid[i][j]这个点是障碍物, 那么dp[i][j]保持为0
-           	 	if obstacleGrid[i][j] != 1 {
+			if obstacleGrid[i][j] != 1 {
 				// 否则我们需要计算当前点可以到达的路径数
-				dp[i][j] = dp[i-1][j]+dp[i][j-1]
+				dp[i][j] = dp[i-1][j] + dp[i][j-1]
 			}
 		}
 	}
-	// debug遍历dp
-	//for i,_ := range dp {
-	//	for j,_ := range dp[i] {
-	//		fmt.Printf("%.2v,",dp[i][j])
-	//	}
-	//	fmt.Println()
-	//}
 	return dp[m-1][n-1]
 }
 
+
 ```
 
 Javascript

problems/0110.平衡二叉树.md

@@ -730,5 +730,33 @@ bool isBalanced(struct TreeNode* root){
 }
 ```
 
+## Swift:
+
+>递归
+```swift
+func isBalanced(_ root: TreeNode?) -> Bool {
+    // -1 已经不是平衡二叉树
+    return getHeight(root) == -1 ? false : true
+}
+func getHeight(_ root: TreeNode?) -> Int {
+    guard let root = root else {
+        return 0
+    }
+    let leftHeight = getHeight(root.left)
+    if leftHeight == -1 {
+        return -1
+    }
+    let rightHeight = getHeight(root.right)
+    if rightHeight == -1 {
+        return -1
+    }
+    if abs(leftHeight - rightHeight) > 1 {
+        return -1
+    } else {
+        return 1 + max(leftHeight, rightHeight)
+    }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0151.翻转字符串里的单词.md

@@ -553,6 +553,65 @@ function reverse(strArr, start, end) {
 }
 ```
 
+TypeScript：
+
+```typescript
+function reverseWords(s: string): string {
+    /** Utils **/
+    // 删除多余空格, 如'   hello     world   ' => 'hello world'
+    function delExtraSpace(arr: string[]): void {
+        let left: number = 0,
+            right: number = 0,
+            length: number = arr.length;
+        while (right < length && arr[right] === ' ') {
+            right++;
+        }
+        while (right < length) {
+            if (arr[right] === ' ' && arr[right - 1] === ' ') {
+                right++;
+                continue;
+            }
+            arr[left++] = arr[right++];
+        }
+        if (arr[left - 1] === ' ') {
+            arr.length = left - 1;
+        } else {
+            arr.length = left;
+        }
+    }
+    // 翻转字符串，如：'hello' => 'olleh'
+    function reverseWords(strArr: string[], start: number, end: number) {
+        let temp: string;
+        while (start < end) {
+            temp = strArr[start];
+            strArr[start] = strArr[end];
+            strArr[end] = temp;
+            start++;
+            end--;
+        }
+    }
+
+    /** Main code **/
+    let strArr: string[] = s.split('');
+    delExtraSpace(strArr);
+    let length: number = strArr.length;
+    // 翻转整个字符串
+    reverseWords(strArr, 0, length - 1);
+    let start: number = 0,
+        end: number = 0;
+    while (start < length) {
+        end = start;
+        while (strArr[end] !== ' ' && end < length) {
+            end++;
+        }
+        // 翻转单个单词
+        reverseWords(strArr, start, end - 1);
+        start = end + 1;
+    }
+    return strArr.join('');
+};
+```
+
 Swift:
 
 ```swift

problems/0257.二叉树的所有路径.md

@@ -581,7 +581,72 @@ var binaryTreePaths = function(root) {
 };  
 ```
 
+Swift:
 
+> 递归/回溯
+```swift
+func binaryTreePaths(_ root: TreeNode?) -> [String] {
+    var res = [String]()
+    guard let root = root else {
+        return res
+    }
+    var path = [Int]()
+    _binaryTreePaths(root, path: &path, res: &res)
+    return res
+}
+func _binaryTreePaths(_ root: TreeNode, path: inout [Int], res: inout [String]) {
+    path.append(root.val)
+    if root.left ==  nil && root.right == nil {
+        var str = ""
+        for i in 0 ..< path.count - 1 {
+            str.append("\(path[i])->")
+        }
+        str.append("\(path.last!)")
+        res.append(str)
+        return
+    }
+    if let left = root.left {
+        _binaryTreePaths(left, path: &path, res: &res)
+        path.removeLast()
+    }
+    if let right = root.right {
+        _binaryTreePaths(right, path: &path, res: &res)
+        path.removeLast()
+    }
+}
+```
+
+> 迭代
+```swift
+func binaryTreePaths(_ root: TreeNode?) -> [String] {
+    var res = [String]()
+    guard let root = root else {
+        return res
+    }
+    var stackNode = [TreeNode]()
+    stackNode.append(root)
+    
+    var stackStr = [String]()
+    stackStr.append("\(root.val)")
+    
+    while !stackNode.isEmpty {
+        let node = stackNode.popLast()!
+        let str = stackStr.popLast()!
+        if node.left == nil && node.right == nil {
+            res.append(str)
+        }
+        if let left = node.left {
+            stackNode.append(left)
+            stackStr.append("\(str)->\(left.val)")
+        }
+        if let right = node.right {
+            stackNode.append(right)
+            stackStr.append("\(str)->\(right.val)")
+        }
+    }
+    return res
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0344.反转字符串.md

@@ -200,6 +200,27 @@ var reverseString = function(s) {
 };
 ```
 
+TypeScript：
+
+```typescript
+/**
+ Do not return anything, modify s in-place instead.
+ */
+function reverseString(s: string[]): void {
+    let length: number = s.length;
+    let left: number = 0,
+        right: number = length - 1;
+    let tempStr: string;
+    while (left < right) {
+        tempStr = s[left];
+        s[left] = s[right];
+        s[right] = tempStr;
+        left++;
+        right--;
+    }
+};
+```
+
 Swift:
 
 ```swift
@@ -232,6 +253,19 @@ void reverseString(char* s, int sSize){
 }
 ```
 
+C#：
+```csharp
+public class Solution
+{
+    public void ReverseString(char[] s)
+    {
+        for (int i = 0, j = s.Length - 1; i < j; i++, j--)
+        {
+            (s[i], s[j]) = (s[j], s[i]);
+        }
+    }
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0494.目标和.md

@@ -289,7 +289,7 @@ func findTargetSumWays(nums []int, target int) int {
 	for _, v := range nums {
 		sum += v
 	}
-	if target > sum {
+	if abs(target) > sum {
 		return 0
 	}
 	if (sum+target)%2 == 1 {
@@ -311,49 +311,12 @@ func findTargetSumWays(nums []int, target int) int {
 	}
 	return dp[bag]
 }
-```
-> 更新版，上一个跑不通了，因为会存在bag 小于0的情况
 
-```go
+func abs(x int) int {
-func findTargetSumWays(nums []int, target int) int {
+	return int(math.Abs(float64(x)))
-    //先转化为数学问题
-    //a-b=target
-    //a+b=sum
-    //a=(target+sum)/2
-    //求出sum
-    var sum int
-    for _,value:=range nums{
-        sum+=value
-    }
-    //如果sum<target或者 sum+target不是偶数（因为a是int） 或者两者之和小于0了
-    if sum<target||(sum+target)%2==1||(sum+target)<0{
-        return 0
-    }
-    //开始dp初始化
-    dp:=make([][]int,len(nums)+1)
-    for i:=0;i<=len(nums);i++{
-        tmp:=make([]int,(target+sum)/2+1)//背包容量
-        dp[i]=tmp
-    }
-    dp[0][0]=1//当背包容量为0，且物品为0时，填满背包就1种方法
-    for i:=0;i<len(nums)+1;i++{
-        if i==0{
-            continue
-        }
-        for j:=0;j<(target+sum)/2+1;j++{
-            if nums[i-1]<=j{//如果背包装的下
-                dp[i][j]=dp[i-1][j]+dp[i-1][j-nums[i-1]]
-            }else{
-                dp[i][j]=dp[i-1][j]
-            }
-        }
-    }
-    return dp[len(nums)][(target+sum)/2]
 }
 ```
 
-
-
 Javascript：
 ```javascript
 const findTargetSumWays = (nums, target) => {

problems/0541.反转字符串II.md

@@ -252,6 +252,28 @@ var reverseStr = function(s, k) {
 
 ```
 
+TypeScript：
+
+```typescript
+function reverseStr(s: string, k: number): string {
+    let left: number, right: number;
+    let arr: string[] = s.split('');
+    let temp: string;
+    for (let i = 0, length = arr.length; i < length; i += 2 * k) {
+        left = i;
+        right = (i + k - 1) >= length ? length - 1 : i + k - 1;
+        while (left < right) {
+            temp = arr[left];
+            arr[left] = arr[right];
+            arr[right] = temp;
+            left++;
+            right--;
+        }
+    }
+    return arr.join('');
+};
+```
+
 Swift:
 
 ```swift
@@ -272,9 +294,21 @@ func reverseStr(_ s: String, _ k: Int) -> String {
 }
 ```
 
-
+C#：
-
+```csharp
-
+public class Solution
+{
+    public string ReverseStr(string s, int k)
+    {
+        Span<char> span = s.ToCharArray().AsSpan();
+        for (int i = 0; i < span.Length; i += 2 * k)
+        {
+            span[i + k < span.Length ? i..(i + k) : i..].Reverse();
+        }
+        return span.ToString();
+    }
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0844.比较含退格的字符串.md

@@ -205,6 +205,42 @@ class Solution:
         return self.get_string(s) == self.get_string(t)
         pass
 ```
+双指针
+```python
+class Solution:
+    def backspaceCompare(self, s: str, t: str) -> bool:
+        s_index, t_index = len(s) - 1, len(t) - 1
+        s_backspace, t_backspace = 0, 0 # 记录s,t的#数量
+        while s_index >= 0 or t_index >= 0: # 使用or，以防长度不一致
+            while s_index >= 0: # 从后向前，消除s的#
+                if s[s_index] == '#':
+                    s_index -= 1
+                    s_backspace += 1
+                else:
+                    if s_backspace > 0:
+                        s_index -= 1
+                        s_backspace -= 1
+                    else:
+                        break
+            while t_index >= 0: # 从后向前，消除t的#
+                if t[t_index] == '#':
+                    t_index -= 1
+                    t_backspace += 1
+                else:
+                    if t_backspace > 0:
+                        t_index -= 1
+                        t_backspace -= 1
+                    else:
+                        break
+            if s_index >= 0 and t_index >= 0: # 后半部分#消除完了，接下来比较当前位的值
+                if s[s_index] != t[t_index]:
+                    return False
+            elif s_index >= 0 or t_index >= 0: # 一个字符串找到了待比较的字符，另一个没有，返回False
+                return False
+            s_index -= 1
+            t_index -= 1
+        return True
+```
 
 ### Go 
 
@@ -226,6 +262,51 @@ func backspaceCompare(s string, t string) bool {
 	return getString(s) == getString(t)
 }
 
+```
+双指针
+```go
+func backspaceCompare(s string, t string) bool {
+    s_index, t_index := len(s) - 1, len(t) - 1
+    s_backspace, t_backspace := 0, 0 // 记录s,t的#数量
+    for s_index >= 0 || t_index >= 0 { // 使用or，以防长度不一致
+        for s_index >= 0 { // 从后向前，消除s的#
+            if s[s_index] == '#' {
+                s_index--
+                s_backspace++
+            } else {
+                if s_backspace > 0 {
+                    s_index--
+                    s_backspace--
+                } else {
+                    break
+                }
+            }            
+        }
+        for t_index >= 0 { // 从后向前，消除t的#
+            if t[t_index] == '#' {
+                t_index--
+                t_backspace++
+            } else {
+                if t_backspace > 0 {
+                    t_index--
+                    t_backspace--
+                } else {
+                    break
+                }
+            }            
+        }
+        if s_index >= 0 && t_index >= 0 { // 后半部分#消除完了，接下来比较当前位的值
+            if s[s_index] != t[t_index] {
+                return false
+            } 
+        } else if s_index >= 0 || t_index >= 0 { // 一个字符串找到了待比较的字符，另一个没有，返回false
+            return false
+        }            
+        s_index--
+        t_index--
+    }      
+    return true
+}
 ```
 
 ### JavaScript 

problems/剑指Offer05.替换空格.md

@@ -298,6 +298,33 @@ javaScript:
 };
 ```
 
+TypeScript：
+
+```typescript
+function replaceSpace(s: string): string {
+    let arr: string[] = s.split('');
+    let spaceNum: number = 0;
+    let oldLength: number = arr.length;
+    for (let i = 0; i < oldLength; i++) {
+        if (arr[i] === ' ') {
+            spaceNum++;
+        }
+    }
+    arr.length = oldLength + 2 * spaceNum;
+    let cur: number = oldLength - 1;
+    for (let i = arr.length - 1; i >= 0; i--, cur--) {
+        if (arr[cur] !== ' ') {
+            arr[i] = arr[cur]
+        } else {
+            arr[i] = '0';
+            arr[--i] = '2';
+            arr[--i] = '%';
+        }
+    }
+    return arr.join('');
+};
+```
+
 Swift:
 
 ```swift

problems/剑指Offer58-II.左旋转字符串.md

@@ -209,6 +209,61 @@ var reverseLeftWords = function(s, n) {
 };
 ```
 
+版本二（在原字符串上操作）：
+
+```js
+/**
+ * @param {string} s
+ * @param {number} n
+ * @return {string}
+ */
+var reverseLeftWords = function (s, n) {
+    /** Utils */
+    function reverseWords(strArr, start, end) {
+        let temp;
+        while (start < end) {
+            temp = strArr[start];
+            strArr[start] = strArr[end];
+            strArr[end] = temp;
+            start++;
+            end--;
+        }
+    }
+    /** Main code */
+    let strArr = s.split('');
+    let length = strArr.length;
+    reverseWords(strArr, 0, length - 1);
+    reverseWords(strArr, 0, length - n - 1);
+    reverseWords(strArr, length - n, length - 1);
+    return strArr.join('');
+};
+```
+
+TypeScript：
+
+```typescript
+function reverseLeftWords(s: string, n: number): string {
+    /** Utils */
+    function reverseWords(strArr: string[], start: number, end: number): void {
+        let temp: string;
+        while (start < end) {
+            temp = strArr[start];
+            strArr[start] = strArr[end];
+            strArr[end] = temp;
+            start++;
+            end--;
+        }
+    }
+    /** Main code */
+    let strArr: string[] = s.split('');
+    let length: number = strArr.length;
+    reverseWords(strArr, 0, length - 1);
+    reverseWords(strArr, 0, length - n - 1);
+    reverseWords(strArr, length - n, length - 1);
+    return strArr.join('');
+};
+```
+
 Swift:
 
 ```swift

problems/链表理论基础.md

@@ -195,10 +195,20 @@ class ListNode {
 ```
 
 Python：
-
+```python
+class ListNode:
+    def __init__(self, val, next=None):
+        self.val = val
+        self.next = next
+```
 
 Go：
-
+```go
+type ListNode struct {
+    Val int
+    Next *ListNode
+}
+```