diff --git a/problems/0015.三数之和.md b/problems/0015.三数之和.md
index 55e22887..96dc1ac3 100644
--- a/problems/0015.三数之和.md
+++ b/problems/0015.三数之和.md
@@ -221,6 +221,40 @@ Python：
 
 
 Go：
+```Go
+func threeSum(nums []int)[][]int{
+	sort.Ints(nums)
+	res:=[][]int{}
+	
+	for i:=0;i<len(nums)-2;i++{
+		n1:=nums[i]
+		if n1>0{
+			break
+		}
+		if i>0&&n1==nums[i-1]{
+			continue
+		}
+		l,r:=i+1,len(nums)-1
+		for l<r{
+			n2,n3:=nums[l],nums[r]
+			if n1+n2+n3==0{
+				res=append(res,[]int{n1,n2,n3})
+				for l<r&&nums[l]==n2{
+					l++
+				}
+				for l<r&&nums[r]==n3{
+					r--
+				}
+			}else if n1+n2+n3<0{
+				l++
+			}else {
+				r--
+			}
+		}
+	}
+	return res
+}
+```
 
 
 
diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md
index 6f51a181..f06ed80a 100644
--- a/problems/0017.电话号码的字母组合.md
+++ b/problems/0017.电话号码的字母组合.md
@@ -240,7 +240,46 @@ public:
 
 
 Java：
+```Java
+class Solution {
 
+    //设置全局列表存储最后的结果
+    List<String> list = new ArrayList<>();
+
+    public List<String> letterCombinations(String digits) {
+        if (digits == null || digits.length() == 0) {
+            return list;
+        }
+        //初始对应所有的数字，为了直接对应2-9，新增了两个无效的字符串""
+        String[] numString = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
+        //迭代处理
+        backTracking(digits, numString, 0);
+        return list;
+
+    }
+
+    //每次迭代获取一个字符串，所以会设计大量的字符串拼接，所以这里选择更为高效的 StringBuild
+    StringBuilder temp = new StringBuilder();
+
+    //比如digits如果为"23",num 为0，则str表示2对应的 abc
+    public void backTracking(String digits, String[] numString, int num) {
+        //遍历全部一次记录一次得到的字符串
+        if (num == digits.length()) {
+            list.add(temp.toString());
+            return;
+        }
+        //str 表示当前num对应的字符串
+        String str = numString[digits.charAt(num) - '0'];
+        for (int i = 0; i < str.length(); i++) {
+            temp.append(str.charAt(i));
+            //回溯
+            backTracking(digits, numString, num + 1);
+            //剔除末尾的继续尝试
+            temp.deleteCharAt(temp.length() - 1);
+        }
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0019.删除链表的倒数第N个节点.md b/problems/0019.删除链表的倒数第N个节点.md
index 3b6dde1e..3b89dabd 100644
--- a/problems/0019.删除链表的倒数第N个节点.md
+++ b/problems/0019.删除链表的倒数第N个节点.md
@@ -112,7 +112,28 @@ class Solution {
     }
 }
 ```
+Go:
+```Go
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    result:=&ListNode{}
+    result.Next=head
+    var pre *ListNode
+    cur:=result
 
+    i:=1
+    for head!=nil{
+        if i>=n{
+            pre=cur
+            cur=cur.Next
+        }
+        head=head.Next
+        i++
+    }
+    pre.Next=pre.Next.Next
+    return result.Next
+
+}
+```
 
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
diff --git a/problems/0020.有效的括号.md b/problems/0020.有效的括号.md
index f2d78ade..9f6c8487 100644
--- a/problems/0020.有效的括号.md
+++ b/problems/0020.有效的括号.md
@@ -138,7 +138,31 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public boolean isValid(String s) {
+        Deque<Character> deque = new LinkedList<>();
+        char ch;
+        for (int i = 0; i < s.length(); i++) {
+            ch = s.charAt(i);
+            //碰到左括号，就把相应的右括号入栈
+            if (ch == '(') {
+                deque.push(')');
+            }else if (ch == '{') {
+                deque.push('}');
+            }else if (ch == '[') {
+                deque.push(']');
+            } else if (deque.isEmpty() || deque.peek() != ch) {
+                return false;
+            }else {//如果是右括号判断是否和栈顶元素匹配
+                deque.pop();
+            }
+        }
+        //最后判断栈中元素是否匹配
+        return deque.isEmpty();
+    }
+}
+```
 
 Python：
 ```python3
@@ -157,7 +181,26 @@ class Solution:
 ```
 
 Go：
+```Go
+func isValid(s string) bool {
+    hash := map[byte]byte{')':'(', ']':'[', '}':'{'}
+    stack := make([]byte, 0)
+    if s == "" {
+        return true
+    }
 
+    for i := 0; i < len(s); i++ {
+        if s[i] == '(' || s[i] == '[' || s[i] == '{' {
+            stack = append(stack, s[i])
+        } else if len(stack) > 0 && stack[len(stack)-1] == hash[s[i]] {
+            stack = stack[:len(stack)-1]
+        } else {
+            return false
+        }
+    }
+    return len(stack) == 0
+}
+```
 
 
 
diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md
index 144cd5be..959474fc 100644
--- a/problems/0027.移除元素.md
+++ b/problems/0027.移除元素.md
@@ -124,9 +124,19 @@ public:
 
 Java：
 
-
 Python：
 
+```python
+class Solution:
+    def removeElement(self, nums: List[int], val: int) -> int:
+        i,n = 0,len(nums)
+        for j in range(n):
+            if nums[j] != val:
+                nums[i] = nums[j]
+                i += 1
+        return i
+```
+
 
 Go：
 ```go
@@ -162,4 +172,4 @@ var removeElement = (nums, val) => {
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0035.搜索插入位置.md b/problems/0035.搜索插入位置.md
index c351e365..e891e3c5 100644
--- a/problems/0035.搜索插入位置.md
+++ b/problems/0035.搜索插入位置.md
@@ -237,6 +237,22 @@ class Solution {
 
 
 Python：
+```python3
+class Solution:
+    def searchInsert(self, nums: List[int], target: int) -> int:
+        left, right = 0, len(nums) - 1 
+        
+        while left <= right:
+            middle = (left + right) // 2
+            
+            if nums[middle] < target:
+                left = middle + 1
+            elif nums[middle] > target:
+                right = middle - 1
+            else: 
+                return middle
+        return right + 1
+```
 
 
 Go：
diff --git a/problems/0053.最大子序和.md b/problems/0053.最大子序和.md
index b8b11a57..6474d01f 100644
--- a/problems/0053.最大子序和.md
+++ b/problems/0053.最大子序和.md
@@ -160,11 +160,44 @@ class Solution {
 ```
 
 Python：
-
+```python
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        result = -float('inf')
+        count = 0
+        for i in range(len(nums)):
+            count += nums[i]
+            if count > result:
+                result = count
+            if count <= 0:
+                count = 0
+        return result
+```
 
 Go：
+```Go
+func maxSubArray(nums []int) int {
+    if len(nums)<1{
+        return 0
+    }
+    dp:=make([]int,len(nums))
+    result:=nums[0]
+    dp[0]=nums[0]
+    for i:=1;i<len(nums);i++{
+        dp[i]=max(dp[i-1]+nums[i],nums[i])
+        result=max(dp[i],result)
+    }
+    return result
+}
 
-
+func max(a,b int)int{
+    if a>b{
+        return a
+    }else{
+        return b
+    }
+}
+```
 
 
 -----------------------
diff --git a/problems/0070.爬楼梯.md b/problems/0070.爬楼梯.md
index 6ae6adc7..f0a08f99 100644
--- a/problems/0070.爬楼梯.md
+++ b/problems/0070.爬楼梯.md
@@ -230,7 +230,20 @@ class Solution:
 ```
 
 Go：
-
+```Go
+func climbStairs(n int) int {
+    if n==1{
+        return 1
+    }
+    dp:=make([]int,n+1)
+    dp[1]=1
+    dp[2]=2
+    for i:=3;i<=n;i++{
+        dp[i]=dp[i-1]+dp[i-2]
+    }
+    return dp[n]
+}
+```
 
 
 
diff --git a/problems/0077.组合优化.md b/problems/0077.组合优化.md
index 2af123d1..a8a17858 100644
--- a/problems/0077.组合优化.md
+++ b/problems/0077.组合优化.md
@@ -147,7 +147,33 @@ public:
 
 
 Java：
+```
+class Solution {
+    List<List<Integer>> result = new ArrayList<>();
+    LinkedList<Integer> path = new LinkedList<>();
+    public List<List<Integer>> combine(int n, int k) {
+        combineHelper(n, k, 1);
+        return result;
+    }
 
+    /**
+     * 每次从集合中选取元素，可选择的范围随着选择的进行而收缩，调整可选择的范围，就是要靠startIndex
+     * @param startIndex 用来记录本层递归的中，集合从哪里开始遍历（集合就是[1,...,n] ）。
+     */
+    private void combineHelper(int n, int k, int startIndex){
+        //终止条件
+        if (path.size() == k){
+            result.add(new ArrayList<>(path));
+            return;
+        }
+        for (int i = startIndex; i <= n - (k - path.size()) + 1; i++){
+            path.add(i);
+            combineHelper(n, k, i + 1);
+            path.removeLast();
+        }
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0078.子集.md b/problems/0078.子集.md
index a61d7493..7166f7fa 100644
--- a/problems/0078.子集.md
+++ b/problems/0078.子集.md
@@ -209,6 +209,28 @@ Python：
 
 
 Go：
+```Go
+var res [][]int
+func subset(nums []int) [][]int {
+	res = make([][]int, 0)
+	sort.Ints(nums)
+	Dfs([]int{}, nums, 0)
+	return res
+}
+func Dfs(temp, nums []int, start int){
+	tmp := make([]int, len(temp))
+	copy(tmp, temp)
+	res = append(res, tmp)
+	for i := start; i < len(nums); i++{
+		//if i>start&&nums[i]==nums[i-1]{
+		//	continue
+		//}
+		temp = append(temp, nums[i])
+		Dfs(temp, nums, i+1)
+		temp = temp[:len(temp)-1]
+	}
+}
+```
 
 Javascript:
 
diff --git a/problems/0096.不同的二叉搜索树.md b/problems/0096.不同的二叉搜索树.md
index 2764277c..7dea8fb0 100644
--- a/problems/0096.不同的二叉搜索树.md
+++ b/problems/0096.不同的二叉搜索树.md
@@ -165,7 +165,25 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public int numTrees(int n) {
+        //初始化 dp 数组
+        int[] dp = new int[n + 1];
+        //初始化0个节点和1个节点的情况
+        dp[0] = 1;
+        dp[1] = 1;
+        for (int i = 2; i <= n; i++) {
+            for (int j = 1; j <= i; j++) {
+                //对于第i个节点，需要考虑1作为根节点直到i作为根节点的情况，所以需要累加
+                //一共i个节点，对于根节点j时,左子树的节点个数为j-1，右子树的节点个数为i-j
+                dp[i] += dp[j - 1] * dp[i - j];
+            }
+        }
+        return dp[n];
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0098.验证二叉搜索树.md b/problems/0098.验证二叉搜索树.md
index baa3f435..ddd634b4 100644
--- a/problems/0098.验证二叉搜索树.md
+++ b/problems/0098.验证二叉搜索树.md
@@ -260,7 +260,25 @@ Python：
 
 
 Go：
+```Go
+import "math"
 
+func isValidBST(root *TreeNode) bool {
+	if root == nil {
+		return true
+	}
+	return isBST(root, math.MinInt64, math.MaxFloat64)
+}
+func isBST(root *TreeNode, min, max int) bool {
+	if root == nil {
+		return true
+	}
+	if min >= root.Val || max <= root.Val {
+		return false
+	}
+	return isBST(root.Left, min, root.Val) && isBST(root.Right, root.Val, max)
+}
+```
 
 
 
diff --git a/problems/0101.对称二叉树.md b/problems/0101.对称二叉树.md
index 561d0470..535300af 100644
--- a/problems/0101.对称二叉树.md
+++ b/problems/0101.对称二叉树.md
@@ -253,7 +253,6 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
 
@@ -284,4 +283,4 @@ const check = (leftPtr, rightPtr) => {
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md
index be2e9dca..0781e01d 100644
--- a/problems/0102.二叉树的层序遍历.md
+++ b/problems/0102.二叉树的层序遍历.md
@@ -419,18 +419,17 @@ public:
 
 Java：
 
-``` Java
-
-
+```Java
 class Solution {
     public List<List<Integer>> resList=new ArrayList<List<Integer>>();
     public List<List<Integer>> levelOrder(TreeNode root) {
-        checkFun01(root,0);
-
+        //checkFun01(root,0);
+        checkFun02(root);
+        
         return resList;
     }
 
-	//递归方式
+	//DFS--递归方式
     public void checkFun01(TreeNode node,Integer deep){
         if(node==null) return;
         deep++;
@@ -442,12 +441,33 @@ class Solution {
         }
         resList.get(deep-1).add(node.val);
         
-
         checkFun01(node.left,deep);
         checkFun01(node.right,deep);
     }
+    
+    //BFS--迭代方式--借助队列
+     public void checkFun02(TreeNode node){
+        if(node==null) return;
+        Queue<TreeNode> que=new LinkedList<TreeNode>();
+        que.offer(node);
 
+        while(!que.isEmpty()){
+            List<Integer> itemList=new ArrayList<Integer>();
+            int len=que.size();
 
+            while(len>0){
+                TreeNode tmpNode=que.poll();
+                itemList.add(tmpNode.val);
+
+                if(tmpNode.left!=null) que.offer(tmpNode.left);
+                if(tmpNode.right!=null) que.offer(tmpNode.right);
+                len--;
+            }
+            
+            resList.add(itemList);
+        }
+
+    }
 ```
 
 
@@ -458,7 +478,6 @@ Go：
 
 
 
-
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
diff --git a/problems/0110.平衡二叉树.md b/problems/0110.平衡二叉树.md
index 5d55910c..ac66cc40 100644
--- a/problems/0110.平衡二叉树.md
+++ b/problems/0110.平衡二叉树.md
@@ -353,7 +353,6 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
 
@@ -361,7 +360,40 @@ Python：
 
 
 Go：
-
+```Go
+func isBalanced(root *TreeNode) bool {
+    if root==nil{
+        return true
+    }
+    if !isBalanced(root.Left) || !isBalanced(root.Right){
+        return false
+    }
+    LeftH:=maxdepth(root.Left)+1
+    RightH:=maxdepth(root.Right)+1
+    if abs(LeftH-RightH)>1{
+        return false
+    }
+    return true
+}
+func maxdepth(root *TreeNode)int{
+    if root==nil{
+        return 0
+    }
+    return max(maxdepth(root.Left),maxdepth(root.Right))+1
+}
+func max(a,b int)int{
+    if a>b{
+        return a
+    }
+    return b
+}
+func abs(a int)int{
+    if a<0{
+        return -a
+    }
+    return a 
+}
+```
 
 
 
@@ -369,4 +401,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0111.二叉树的最小深度.md b/problems/0111.二叉树的最小深度.md
index 430cd5d6..6c6b4632 100644
--- a/problems/0111.二叉树的最小深度.md
+++ b/problems/0111.二叉树的最小深度.md
@@ -195,9 +195,51 @@ public:
 
 Java：
 
-
 Python：
 
+递归法：
+
+```python
+class Solution:
+    def minDepth(self, root: TreeNode) -> int:
+        if not root:
+            return 0
+        if not root.left and not root.right:
+            return 1
+
+        min_depth = 10**9
+        if root.left:
+            min_depth = min(self.minDepth(root.left), min_depth) # 获得左子树的最小高度
+        if root.right:
+            min_depth = min(self.minDepth(root.right), min_depth) # 获得右子树的最小高度
+        return min_depth + 1
+```
+
+迭代法：
+
+```python
+class Solution:
+    def minDepth(self, root: TreeNode) -> int:
+        if not root:
+            return 0
+        que = deque()
+        que.append(root)
+        res = 1
+
+        while que:
+            for _ in range(len(que)):
+                node = que.popleft()
+                # 当左右孩子都为空的时候，说明是最低点的一层了，退出
+                if not node.left and not node.right:
+                    return res
+                if node.left is not None:
+                    que.append(node.left)
+                if node.right is not None:
+                    que.append(node.right)
+            res += 1
+        return res
+```
+
 
 Go：
 
@@ -208,4 +250,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0131.分割回文串.md b/problems/0131.分割回文串.md
index 01ff35c5..9c86a3bc 100644
--- a/problems/0131.分割回文串.md
+++ b/problems/0131.分割回文串.md
@@ -250,7 +250,46 @@ public:
 
 
 Java：
+```Java
+class Solution {
+    List<List<String>> lists = new ArrayList<>();
+    Deque<String> deque = new LinkedList<>();
 
+    public List<List<String>> partition(String s) {
+        backTracking(s, 0);
+        return lists;
+    }
+
+    private void backTracking(String s, int startIndex) {
+        //如果起始位置大于s的大小，说明找到了一组分割方案
+        if (startIndex >= s.length()) {
+            lists.add(new ArrayList(deque));
+            return;
+        }
+        for (int i = startIndex; i < s.length(); i++) {
+            //如果是回文子串，则记录
+            if (isPalindrome(s, startIndex, i)) {
+                String str = s.substring(startIndex, i + 1);
+                deque.addLast(str);
+            } else {
+                continue;
+            }
+            //起始位置后移，保证不重复
+            backTracking(s, i + 1);
+            deque.removeLast();
+        }
+    }
+    //判断是否是回文串
+    private boolean isPalindrome(String s, int startIndex, int end) {
+        for (int i = startIndex, j = end; i < j; i++, j--) {
+            if (s.charAt(i) != s.charAt(j)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0198.打家劫舍.md b/problems/0198.打家劫舍.md
index b9ccec45..c64648ad 100644
--- a/problems/0198.打家劫舍.md
+++ b/problems/0198.打家劫舍.md
@@ -117,6 +117,33 @@ Python：
 
 
 Go：
+```Go
+func rob(nums []int) int {
+	if len(nums)<1{
+		return 0
+	}
+	if len(nums)==1{
+		return nums[0]
+	}
+	if len(nums)==2{
+		return max(nums[0],nums[1])
+	}
+	dp :=make([]int,len(nums))
+	dp[0]=nums[0]
+	dp[1]=max(nums[0],nums[1])
+	for i:=2;i<len(nums);i++{
+		dp[i]=max(dp[i-2]+nums[i],dp[i-1])
+	}
+	return dp[len(dp)-1]
+}
+
+func max(a, b int) int {
+	if a>b{
+		return a
+	}
+	return b
+}
+```
 
 
 
diff --git a/problems/0225.用队列实现栈.md b/problems/0225.用队列实现栈.md
index 49b5c62b..4018364a 100644
--- a/problems/0225.用队列实现栈.md
+++ b/problems/0225.用队列实现栈.md
@@ -154,9 +154,58 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
+```java
+class MyStack {
+
+    Queue<Integer> queue1; // 和栈中保持一样元素的队列
+    Queue<Integer> queue2; // 辅助队列
+
+    /** Initialize your data structure here. */
+    public MyStack() {
+        queue1 = new LinkedList<>();
+        queue2 = new LinkedList<>();
+    }
+    
+    /** Push element x onto stack. */
+    public void push(int x) {
+        queue2.offer(x); // 先放在辅助队列中
+        while (!queue1.isEmpty()){
+            queue2.offer(queue1.poll());
+        }
+        Queue<Integer> queueTemp;
+        queueTemp = queue1;
+        queue1 = queue2;
+        queue2 = queueTemp; // 最后交换queue1和queue2，将元素都放到queue1中
+    }
+    
+    /** Removes the element on top of the stack and returns that element. */
+    public int pop() {
+        return queue1.poll(); // 因为queue1中的元素和栈中的保持一致，所以这个和下面两个的操作只看queue1即可
+    }
+    
+    /** Get the top element. */
+    public int top() {
+        return queue1.peek();
+    }
+    
+    /** Returns whether the stack is empty. */
+    public boolean empty() {
+        return queue1.isEmpty();
+    }
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */
+```
+
 
 Python：
 
@@ -227,4 +276,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0226.翻转二叉树.md b/problems/0226.翻转二叉树.md
index afc1f144..ec1335c6 100644
--- a/problems/0226.翻转二叉树.md
+++ b/problems/0226.翻转二叉树.md
@@ -208,8 +208,21 @@ Java：
 Python：
 
 
-Go：
+```Go
+func invertTree(root *TreeNode) *TreeNode {
+    if root ==nil{
+        return nil
+    }
+    temp:=root.Left
+    root.Left=root.Right
+    root.Right=temp
+    
+    invertTree(root.Left)
+    invertTree(root.Right)
 
+    return root
+}
+```
 
 
 
diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md
index 9907b476..abdc363d 100644
--- a/problems/0232.用栈实现队列.md
+++ b/problems/0232.用栈实现队列.md
@@ -19,7 +19,7 @@ push(x) -- 将一个元素放入队列的尾部。
 pop() -- 从队列首部移除元素。
 peek() -- 返回队列首部的元素。
 empty() -- 返回队列是否为空。
- 
+
 
 示例:
 
@@ -129,9 +129,62 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
+```java
+class MyQueue {
+
+    Stack<Integer> stack1;
+    Stack<Integer> stack2;
+
+    /** Initialize your data structure here. */
+    public MyQueue() {
+        stack1 = new Stack<>(); // 负责进栈
+        stack2 = new Stack<>(); // 负责出栈
+    }
+    
+    /** Push element x to the back of queue. */
+    public void push(int x) {
+        stack1.push(x);
+    }
+    
+    /** Removes the element from in front of queue and returns that element. */
+    public int pop() {    
+        dumpStack1();
+        return stack2.pop();
+    }
+    
+    /** Get the front element. */
+    public int peek() {
+        dumpStack1();
+        return stack2.peek();
+    }
+    
+    /** Returns whether the queue is empty. */
+    public boolean empty() {
+        return stack1.isEmpty() && stack2.isEmpty();
+    }
+
+    // 如果stack2为空，那么将stack1中的元素全部放到stack2中
+    private void dumpStack1(){
+        if (stack2.isEmpty()){
+            while (!stack1.isEmpty()){
+                stack2.push(stack1.pop());
+            }
+        }
+    }
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */
+```
+
 
 Python：
 
@@ -145,4 +198,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0239.滑动窗口最大值.md b/problems/0239.滑动窗口最大值.md
index 709fa09e..781bfa6f 100644
--- a/problems/0239.滑动窗口最大值.md
+++ b/problems/0239.滑动窗口最大值.md
@@ -207,7 +207,60 @@ public:
 
 
 Java：
+```Java
+//自定义数组
+class MyQueue {
+    Deque<Integer> deque = new LinkedList<>();
+    //弹出元素时，比较当前要弹出的数值是否等于队列出口的数值，如果相等则弹出
+    //同时判断队列当前是否为空
+    void poll(int val) {
+        if (!deque.isEmpty() && val == deque.peek()) {
+            deque.poll();
+        }
+    }
+    //添加元素时，如果要添加的元素大于入口处的元素，就将入口元素弹出
+    //保证队列元素单调递减
+    //比如此时队列元素3,1，2将要入队，比1大，所以1弹出，此时队列：3,2
+    void add(int val) {
+        while (!deque.isEmpty() && val > deque.getLast()) {
+            deque.removeLast();
+        }
+        deque.add(val);
+    }
+    //队列队顶元素始终为最大值
+    int peek() {
+        return deque.peek();
+    }
+}
 
+class Solution {
+    public int[] maxSlidingWindow(int[] nums, int k) {
+        if (nums.length == 1) {
+            return nums;
+        }
+        int len = nums.length - k + 1;
+        //存放结果元素的数组
+        int[] res = new int[len];
+        int num = 0;
+        //自定义队列
+        MyQueue myQueue = new MyQueue();
+        //先将前k的元素放入队列
+        for (int i = 0; i < k; i++) {
+            myQueue.add(nums[i]);
+        }
+        res[num++] = myQueue.peek();
+        for (int i = k; i < nums.length; i++) {
+            //滑动窗口移除最前面的元素，移除是判断该元素是否放入队列
+            myQueue.poll(nums[i - k]);
+            //滑动窗口加入最后面的元素
+            myQueue.add(nums[i]);
+            //记录对应的最大值
+            res[num++] = myQueue.peek();
+        }
+        return res;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0279.完全平方数.md b/problems/0279.完全平方数.md
index 39260926..d72e9099 100644
--- a/problems/0279.完全平方数.md
+++ b/problems/0279.完全平方数.md
@@ -159,7 +159,28 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public int numSquares(int n) {
+        int max = Integer.MAX_VALUE;
+        int[] dp = new int[n + 1];
+        //初始化
+        for (int j = 0; j <= n; j++) {
+            dp[j] = max;
+        }
+        //当和为0时，组合的个数为0
+        dp[0] = 0;
+        for (int i = 1; i * i <= n; i++) {
+            for (int j = i * i; j <= n; j++) {
+                if (dp[j - i * i] != max) {
+                    dp[j] = Math.min(dp[j], dp[j - i * i] + 1);
+                }
+            }
+        }
+        return dp[n];
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0344.反转字符串.md b/problems/0344.反转字符串.md
index ddb9805d..b4c843b7 100644
--- a/problems/0344.反转字符串.md
+++ b/problems/0344.反转字符串.md
@@ -140,12 +140,37 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public void reverseString(char[] s) {
+        int l = 0;
+        int r = s.length - 1;
+        while (l < r) {
+            s[l] ^= s[r];  //构造 a ^ b 的结果，并放在 a 中
+            s[r] ^= s[l];  //将 a ^ b 这一结果再 ^ b ，存入b中，此时 b = a, a = a ^ b
+            s[l] ^= s[r];  //a ^ b 的结果再 ^ a ，存入 a 中，此时 b = a, a = b 完成交换
+            l++;
+            r--;
+        }
+    }
+}
+```
 
 Python：
 
 
 Go：
+```Go
+func reverseString(s []byte)  {
+    left:=0
+    right:=len(s)-1
+    for left<right{
+        s[left],s[right]=s[right],s[left]
+        left++
+        right--
+    }
+}
+```
 
 
 
diff --git a/problems/0349.两个数组的交集.md b/problems/0349.两个数组的交集.md
index 195dbad5..b5116ee1 100644
--- a/problems/0349.两个数组的交集.md
+++ b/problems/0349.两个数组的交集.md
@@ -75,28 +75,35 @@ public:
 
 
 Java：
-```java
+
+```Java
+import java.util.HashSet;
+import java.util.Set;
+
 class Solution {
     public int[] intersection(int[] nums1, int[] nums2) {
-        Set<Integer> record = new HashSet<Integer>();
-        Set<Integer> unique = new HashSet<Integer>();
-
-        for (int num : nums1) {
-            record.add(num);
+        if (nums1 == null || nums1.length == 0 || nums2 == null || nums2.length == 0) {
+            return new int[0];
         }
-
-        for (int num : nums2) {
-            if (record.contains(num)) {
-                unique.add(num);
+        Set<Integer> set1 = new HashSet<>();
+        Set<Integer> resSet = new HashSet<>();
+        //遍历数组1
+        for (int i : nums1) {
+            set1.add(i);
+        }
+        //遍历数组2的过程中判断哈希表中是否存在该元素
+        for (int i : nums2) {
+            if (set1.contains(i)) {
+                resSet.add(i);
             }
         }
-
-        int[] res = new int[unique.size()];
+        int[] resArr = new int[resSet.size()];
         int index = 0;
-        for (int num : unique) {
-            res[index++] = num;
+        //将结果几何转为数组
+        for (int i : resSet) {
+            resArr[index++] = i;
         }
-        return res;
+        return resArr;
     }
 }
 ```
diff --git a/problems/0376.摆动序列.md b/problems/0376.摆动序列.md
index 6ae76526..fa90142d 100644
--- a/problems/0376.摆动序列.md
+++ b/problems/0376.摆动序列.md
@@ -111,7 +111,31 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public int wiggleMaxLength(int[] nums) {
+        if (nums == null || nums.length <= 1) {
+            return nums.length;
+        }
+        //当前差值
+        int curDiff = 0;
+        //上一个差值
+        int preDiff = 0;
+        int count = 1;
+        for (int i = 1; i < nums.length; i++) {
+            //得到当前差值
+            curDiff = nums[i] - nums[i - 1];
+            //如果当前差值和上一个差值为一正一负
+            //等于0的情况表示初始时的preDiff
+            if ((curDiff > 0 && preDiff <= 0) || (curDiff < 0 && preDiff >= 0)) {
+                count++;
+                preDiff = curDiff;
+            }
+        }
+        return count;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md
index 8ff2b320..da4ed666 100644
--- a/problems/0404.左叶子之和.md
+++ b/problems/0404.左叶子之和.md
@@ -159,9 +159,51 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
+**递归**
+
+```java
+class Solution {
+    public int sumOfLeftLeaves(TreeNode root) {
+        if (root == null) return 0;
+        int leftValue = sumOfLeftLeaves(root.left);    // 左
+        int rightValue = sumOfLeftLeaves(root.right);  // 右
+                                                       
+        int midValue = 0;
+        if (root.left != null && root.left.left == null && root.left.right == null) { // 中
+            midValue = root.left.val;
+        }
+        int sum = midValue + leftValue + rightValue;
+        return sum;
+    }
+}
+```
+
+**迭代**
+
+```java
+class Solution {
+    public int sumOfLeftLeaves(TreeNode root) {
+        if (root == null) return 0;
+        Stack<TreeNode> stack = new Stack<> ();
+        stack.add(root);
+        int result = 0;
+        while (!stack.isEmpty()) {
+            TreeNode node = stack.pop();
+            if (node.left != null && node.left.left == null && node.left.right == null) {
+                result += node.left.val;
+            }
+            if (node.right != null) stack.add(node.right);
+            if (node.left != null) stack.add(node.left);
+        }
+        return result;
+    }
+}
+```
+
+
+
 
 Python：
 
@@ -176,3 +218,4 @@ Go：
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
 <div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+
diff --git a/problems/0450.删除二叉搜索树中的节点.md b/problems/0450.删除二叉搜索树中的节点.md
index ed0cb9d7..6e38b4fe 100644
--- a/problems/0450.删除二叉搜索树中的节点.md
+++ b/problems/0450.删除二叉搜索树中的节点.md
@@ -257,6 +257,44 @@ Python：
 
 
 Go：
+```Go
+func deleteNode(root *TreeNode, key int) *TreeNode {
+    if root==nil{
+        return nil
+    }
+    if key<root.Val{
+        root.Left=deleteNode(root.Left,key)
+        return root
+    }
+    if key>root.Val{
+        root.Right=deleteNode(root.Right,key)
+        return root
+    }
+    if root.Right==nil{
+        return root.Left
+    }
+    if root.Left==nil{
+        return root.Right
+    }
+    minnode:=root.Right
+    for minnode.Left!=nil{
+        minnode=minnode.Left
+    }
+    root.Val=minnode.Val
+    root.Right=deleteNode1(root.Right)
+    return root
+}
+
+func deleteNode1(root *TreeNode)*TreeNode{
+    if root.Left==nil{
+        pRight:=root.Right
+        root.Right=nil
+        return pRight
+    }
+    root.Left=deleteNode1(root.Left)
+    return root
+}
+```
 
 
 
diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md
index 893c92f9..0a92ac8b 100644
--- a/problems/0541.反转字符串II.md
+++ b/problems/0541.反转字符串II.md
@@ -102,7 +102,36 @@ public:
 
 
 Java：
+```Java
+class Solution {
+    public String reverseStr(String s, int k) {
+        StringBuffer res = new StringBuffer();
 
+        for (int i = 0; i < s.length(); i += (2 * k)) {
+            StringBuffer temp = new StringBuffer();
+            // 剩余字符大于 k 个，每隔 2k 个字符的前 k 个字符进行反转
+            if (i + k <= s.length()) {
+                // 反转前 k 个字符
+                temp.append(s.substring(i, i + k));
+                res.append(temp.reverse());
+
+                // 反转完前 k 个字符之后，如果紧接着还有 k 个字符，则直接加入这 k 个字符
+                if (i + 2 * k <= s.length()) {
+                    res.append(s.substring(i + k, i + 2 * k));
+                // 不足 k 个字符，则直接加入剩下所有字符
+                } else {
+                    res.append(s.substring(i + k, s.length()));
+                }
+                continue;
+            }
+            // 剩余字符少于 k 个，则将剩余字符全部反转。
+            temp.append(s.substring(i, s.length()));
+            res.append(temp.reverse());
+        }
+        return res.toString();
+    }
+}
+```
 
 Python：
 
diff --git a/problems/1047.删除字符串中的所有相邻重复项.md b/problems/1047.删除字符串中的所有相邻重复项.md
index 7a06f02d..d5a8c4ed 100644
--- a/problems/1047.删除字符串中的所有相邻重复项.md
+++ b/problems/1047.删除字符串中的所有相邻重复项.md
@@ -122,7 +122,28 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public String removeDuplicates(String S) {
+        Deque<Character> deque = new LinkedList<>();
+        char ch;
+        for (int i = 0; i < S.length(); i++) {
+            ch = S.charAt(i);
+            if (deque.isEmpty() || deque.peek() != ch) {
+                deque.push(ch);
+            } else {
+                deque.pop();
+            }
+        }
+        String str = "";
+        //剩余的元素即为不重复的元素
+        while (!deque.isEmpty()) {
+            str = deque.pop() + str;
+        }
+        return str;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md
index 7881adf3..5f89241b 100644
--- a/problems/剑指Offer05.替换空格.md
+++ b/problems/剑指Offer05.替换空格.md
@@ -129,7 +129,26 @@ for (int i = 0; i < a.size(); i++) {
 
 
 Java：
-
+```Java
+//使用一个新的对象，复制 str，复制的过程对其判断，是空格则替换，否则直接复制，类似于数组复制
+public static String replaceSpace(StringBuffer str) {
+        if (str == null) {
+            return null;
+        }
+		//选用 StringBuilder 单线程使用，比较快，选不选都行
+        StringBuilder sb = new StringBuilder();
+		//使用 sb 逐个复制 str ，碰到空格则替换，否则直接复制
+        for (int i = 0; i < str.length(); i++) {
+		//str.charAt(i) 为 char 类型，为了比较需要将其转为和 " " 相同的字符串类型
+            if (" ".equals(String.valueOf(str.charAt(i)))){
+                sb.append("%20");
+            } else {
+                sb.append(str.charAt(i));
+            }
+        }
+        return sb.toString();
+    }
+```
 
 Python：