题目链接

递归

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode() {}*     TreeNode(int val) { this.val = val; }*     TreeNode(int val, TreeNode left, TreeNode right) {*         this.val = val;*         this.left = left;*         this.right = right;*     }* }*/
class Solution {public TreeNode insertIntoBST(TreeNode root, int val) {if(root == null){TreeNode node = new TreeNode(val);return node;}if(root.val > val){root.left = insertIntoBST(root.left,val);}if(root.val < val){root.right = insertIntoBST(root.right,val);}return root;}
}