110.平衡二叉树.java

/*
 * @lc app=leetcode.cn id=110 lang=java
 *
 * [110] 平衡二叉树
 */

// @lc code=start
/**
 * 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 boolean isBalanced(TreeNode root) {

        if(root==null){
            return true;
        }

        boolean flag=Math.abs(depth(root.left)-depth(root.right))<=1;
        return flag&&isBalanced(root.left)&&isBalanced(root.right);

    }

    public int depth(TreeNode root){
        if(root==null){
            return 0;
        }
        int left=depth(root.left);
        int right=depth(root.right);
        return Math.max(left,right)+1;
    }
}
// @lc code=end