【Leetcode-Easy-110】Balanced Binary Tree

题目

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.

思路

递归
二叉树的深度

程序

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */class Solution {    public boolean isBalanced(TreeNode root) {        if (root == null) return true;        int l = depth(root.left);        int r = depth(root.right);        if (Math.abs(l-r) > 1) return false;        return isBalanced(root.left) && isBalanced(root.right);    }    private int depth(TreeNode root){        if (root == null) return 0;        int l = depth(root.left);        int r = depth(root.right);        return Math.max(l, r) + 1;    }}

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