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

Author: youngyangyang04

problems/0019.删除链表的倒数第N个节点.md

@@ -135,6 +135,28 @@ func removeNthFromEnd(head *ListNode, n int) *ListNode {
 }
 ```
 
+JavaScript:
+
+```js
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+var removeNthFromEnd = function(head, n) {
+    let ret = new ListNode(0, head),
+        slow = fast = ret;
+    while(n--) fast = fast.next;
+    if(!fast) return ret.next;
+    while (fast.next) {
+        fast = fast.next; 
+        slow = slow.next
+    };
+    slow.next = slow.next.next;
+    return ret.next;
+};
+```
+
 -----------------------
 * 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)

problems/0045.跳跃游戏II.md

@@ -193,6 +193,26 @@ class Solution:
 ```
 
 Go：
+```Go
+func jump(nums []int) int {
+	dp:=make([]int ,len(nums))
+	dp[0]=0
+
+	for i:=1;i<len(nums);i++{
+		dp[i]=i
+		for j:=0;j<i;j++{
+			if nums[j]+j>i{
+				dp[i]=min(dp[j]+1,dp[i])
+			}
+		}
+	}
+	return dp[len(nums)-1]
+}
+/*
+dp[i]表示从起点到当前位置的最小跳跃次数
+dp[i]=min(dp[j]+1,dp[i]) 表示从j位置用一步跳跃到当前位置，这个j位置可能有很多个，却最小一个就可以
+*/
+```
 
 
 

problems/0055.跳跃游戏.md

@@ -122,6 +122,24 @@ class Solution:
 ```
 
 Go：
+```Go
+func canJUmp(nums []int) bool {
+	if len(nums)<=1{
+		return true
+	}
+	dp:=make([]bool,len(nums))
+	dp[0]=true
+	for i:=1;i<len(nums);i++{
+		for j:=i-1;j>=0;j--{
+			if dp[j]&&nums[j]+j>=i{
+				dp[i]=true
+				break
+			}
+		}
+	}
+	return dp[len(nums)-1]
+}
+```
 
 
 

problems/0077.组合.md

@@ -370,8 +370,45 @@ class Solution {
 
 
 Python：
-
-
+```python
+class Solution:
+    result: List[List[int]] = []
+    path: List[int] = []
+    def combine(self, n: int, k: int) -> List[List[int]]:
+      self.result = []
+      self.combineHelper(n, k, 1)
+      return self.result
+
+    def combineHelper(self, n: int, k: int, startIndex: int):
+      if  (l := len(self.path)) == k:
+        self.result.append(self.path.copy())
+        return
+      for i in range(startIndex, n - (k - l) + 2):
+        self.path.append(i)
+        self.combineHelper(n, k, i + 1)
+        self.path.pop()
+```
+javascript
+```javascript
+let result = []
+let path = []
+var combine = function(n, k) {
+  result = []
+  combineHelper(n, k, 1)
+  return result
+};
+const combineHelper = (n, k, startIndex) => {
+  if (path.length === k) {
+    result.push([...path])
+    return
+  }
+  for (let i = startIndex; i <= n - (k - path.length) + 1; ++i) {
+    path.push(i)
+    combineHelper(n, k, i + 1)
+    path.pop()
+  }
+}
+```
 Go：
 ```Go
 var res [][]int 

problems/0098.验证二叉搜索树.md

@@ -336,8 +336,26 @@ class Solution {
 ```
 
 Python：
-
-
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+//递归法
+class Solution:
+    def isValidBST(self, root: TreeNode) -> bool:
+        res = []  //把二叉搜索树按中序遍历写成list
+        def buildalist(root):
+            if not root: return  
+            buildalist(root.left)  //左
+            res.append(root.val)  //中
+            buildalist(root.right)  //右
+            return res  
+        buildalist(root)
+        return res == sorted(res) and len(set(res)) == len(res) //检查list里的数有没有重复元素，以及是否按从小到大排列
+```
 Go：
 ```Go
 import "math"
@@ -365,4 +383,4 @@ func isBST(root *TreeNode, min, max int) bool {
 * 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>

problems/0111.二叉树的最小深度.md

@@ -302,6 +302,53 @@ class Solution:
 Go：
 
 
+JavaScript:
+
+递归法：
+
+```javascript
+/**
+    * @param {TreeNode} root
+    * @return {number}
+    */
+var minDepth1 = function(root) {
+    if(!root) return 0;
+    // 到叶子节点 返回 1
+    if(!root.left && !root.right) return 1;
+    // 只有右节点时 递归右节点
+    if(!root.left) return 1 + minDepth(root.right);、
+    // 只有左节点时 递归左节点
+    if(!root.right) return 1 + minDepth(root.left);
+    return Math.min(minDepth(root.left), minDepth(root.right)) + 1;
+};
+```
+
+迭代法：
+
+```javascript
+/**
+* @param {TreeNode} root
+* @return {number}
+*/
+var minDepth = function(root) {
+    if(!root) return 0;
+    const queue = [root];
+    let dep = 0;
+    while(true) {
+        let size = queue.length;
+        dep++;
+        while(size--){
+            const node = queue.shift();
+            // 到第一个叶子节点 返回 当前深度 
+            if(!node.left && !node.right) return dep;
+            node.left && queue.push(node.left);
+            node.right && queue.push(node.right);
+        }
+    }
+};
+```
+
+
 
 
 -----------------------

problems/0139.单词拆分.md

@@ -254,12 +254,30 @@ Python：
 
 
 Go：
-
+```Go
+func wordBreak(s string,wordDict []string) bool  {
+	wordDictSet:=make(map[string]bool)
+	for _,w:=range wordDict{
+		wordDictSet[w]=true
+	}
+	dp:=make([]bool,len(s)+1)
+	dp[0]=true
+	for i:=1;i<=len(s);i++{
+		for j:=0;j<i;j++{
+			if dp[j]&& wordDictSet[s[j:i]]{
+				dp[i]=true
+				break
+			}
+		}
+	}
+	return dp[len(s)]
+}
+```
 
 
 
 -----------------------
 * 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>

problems/0142.环形链表II.md

@@ -258,6 +258,50 @@ Go：
 }
 ```
 
+javaScript
+
+```js
+// 两种循环实现方式
+/**
+ * @param {ListNode} head
+ * @return {ListNode}
+ */
+// 先判断是否是环形链表
+var detectCycle = function(head) {
+    if(!head || !head.next) return null;
+    let slow =head.next, fast = head.next.next;
+    while(fast && fast.next && fast!== slow) {
+        slow = slow.next;
+        fast = fast.next.next; 
+    }
+    if(!fast || !fast.next ) return null;
+    slow = head;
+    while (fast !== slow) {
+        slow = slow.next;
+        fast = fast.next;
+    }
+    return slow;
+};
+
+var detectCycle = function(head) {
+    if(!head || !head.next) return null;
+    let slow =head.next, fast = head.next.next;
+    while(fast && fast.next) {
+        slow = slow.next;
+        fast = fast.next.next;
+        if(fast == slow) {
+            slow = head;
+            while (fast !== slow) {
+                slow = slow.next;
+                fast = fast.next;
+            }
+            return slow;
+        }
+    }
+    return null;
+};
+```
+
 
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)

problems/0202.快乐数.md

@@ -112,6 +112,40 @@ Python：
 
 Go：
 
+javaScript:
+
+```js
+function getN(n) {
+    if (n == 1 || n == 0) return n;
+    let res = 0;
+    while (n) {
+        res += (n % 10) * (n % 10);
+        n = parseInt(n / 10);
+    }
+    return res;
+}
+
+var isHappy = function(n) {
+    const sumSet = new Set();
+    while (n != 1 && !sumSet.has(n)) {
+        sumSet.add(n);
+        n = getN(n);
+    }
+    return n == 1;
+};
+
+// 使用环形链表的思想 说明出现闭环 退出循环
+var isHappy = function(n) {
+    if (getN(n) == 1) return true;
+    let a = getN(n), b = getN(getN(n));
+    // 如果 a === b 
+    while (b !== 1 && getN(b) !== 1 && a !== b) {
+        a = getN(a);
+        b = getN(getN(b));
+    }
+    return b === 1 || getN(b) === 1 ;
+};
+```