添加题450，110

Author: ligecarryme

算法思维/二叉搜索树.md

@@ -43,3 +43,73 @@ function insertIntoBST(root: TreeNode | null, val: number): TreeNode | null{
 };
 ```
 
+##### [450. 删除二叉搜索树中的节点](https://leetcode-cn.com/problems/delete-node-in-a-bst/)
+
+给定一个二叉搜索树的根节点 root 和一个值 key，删除二叉搜索树中的 key 对应的节点，并保证二叉搜索树的性质不变。返回二叉搜索树（有可能被更新）的根节点的引用。
+
+> 思路：[秒懂就完事了](https://leetcode-cn.com/problems/delete-node-in-a-bst/solution/miao-dong-jiu-wan-shi-liao-by-terry2020-tc0o/)
+
+```tsx
+
+function deleteNode(root:TreeNode|null, key:number):TreeNode|null{
+if (root===null){
+returnroot
+ }
+if (root.val<key){
+root.right=deleteNode(root.right, key)
+ } elseif (root.val>key){
+root.left=deleteNode(root.left, key)
+ } else{
+if (root.left===null){
+returnroot.right
+ } elseif (root.right===null){
+returnroot.left
+ } else{
+let cur:TreeNode=root.right
+while (cur.left!==null){
+cur=cur.left
+ }
+cur.left=root.left
+returnroot.right
+ }
+ }
+returnroot
+};
+```
+
+##### [110. 平衡二叉树](https://leetcode-cn.com/problems/balanced-binary-tree/)
+
+给定一个二叉树，判断它是否是高度平衡的二叉树。
+
+```js
+constisBalanced=function (root){
+if (maxDepth(root) ===-1){
+returnfalse
+ }
+returntrue
+};
+
+constmaxDepth=function (root){
+if (root ===null){
+return0
+ }
+constleft=maxDepth(root.left)
+constright=maxDepth(root.right)
+if (left ===-1|| right ===-1||Math.abs(right - left) >1){
+return-1
+ }
+if (left > right){
+return left +1
+ } else{
+return right +1
+ }
+}
+```
+
+## 练习
+
+-[validate-binary-search-tree](https://leetcode-cn.com/problems/validate-binary-search-tree/)
+-[insert-into-a-binary-search-tree](https://leetcode-cn.com/problems/insert-into-a-binary-search-tree/)
+-[delete-node-in-a-bst](https://leetcode-cn.com/problems/delete-node-in-a-bst/)
+-[balanced-binary-tree](https://leetcode-cn.com/problems/balanced-binary-tree/)
+