【LeetCode】Balanced Binary Tree

Balanced Binary Tree 
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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.
平衡二叉树，递归判断即可。

Java AC

/** * 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) {if (root == null) {return true;}int left = dfs(root.left);int right = dfs(root.right);if (left == -1 || right == -1 || Math.abs(left - right) > 1) {return false;}return true;}public int dfs(TreeNode root) {if (root == null) {return 0;}int left = dfs(root.left);int right = dfs(root.right);if (left == -1 || right == -1 || Math.abs(left - right) > 1) {return -1;}return Math.max(left, right) + 1;}}