/*

* @lc app=leetcode id=110 lang=java

*

* [110] Balanced Binary Tree

*/

// @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) {

boolean[] isBalanced = new boolean[]{true};//默认长度为1,也可以写成boolean[] isBalanced = {true};

checkBalanced(root, isBalanced);

return isBalanced[0];

}

public int checkBalanced(TreeNode root, boolean[] isBalanced) {

if (root == null) return 0;

int leftHeight = checkBalanced(root.left, isBalanced);

int rightHeight = checkBalanced(root.right, isBalanced);

if (Math.abs(leftHeight-rightHeight) > 1) isBalanced[0] = false; //这里只需要修改boolean值,并不需要返回中断递归

return Math.max(leftHeight,rightHeight) + 1;

}

}

// @lc code=end