LeetCode-Balanced Binary Tree

题目：https://oj.leetcode.com/problems/balanced-binary-tree/

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

源码：Java版本
算法分析：使用栈。时间复杂度O(n)，空间复杂度O(logn)

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public boolean isBalanced(TreeNode root) {        return balancedHeight(root)>=0?true:false;    }        private int balancedHeight(TreeNode root) {        if(root==null) {            return 0;        }        int left=balancedHeight(root.left);        int right=balancedHeight(root.right);                if(left<0 || right <0 || Math.abs(left-right)>1) {            return -1;        }        return Math.max(left,right)+1;    }}