/**
* Definition of TreeNode:
* public class TreeNode { * public int val; * public TreeNode left, right; * public TreeNode(int val) { * this.val = val; * this.left = this.right = null; * } * } */ class ResultType{ public boolean isBalanced; public int maxDepth; public ResultType(boolean isBalanced, int maxDepth) { this.isBalanced = isBalanced; this.maxDepth = maxDepth; } } public class Solution { /** * @param root: The root of binary tree. * @return: True if this Binary tree is Balanced, or false. */ public boolean isBalanced(TreeNode root) { // write your code here return helper(root).isBalanced; } private ResultType helper(TreeNode root) { if(root == null) { return new ResultType(true, 0); } ResultType left = helper(root.left); ResultType right = helper(root.right); // subtree not balance if(!left.isBalanced || !right.isBalanced) return new ResultType(false, -1); // root not balance if(Math.abs(left.maxDepth - right.maxDepth) > 1) return new ResultType(false, -1); return new ResultType(true, Math.max(left.maxDepth, right.maxDepth)+1); } }
93. 平衡二叉树
给定一个二叉树,确定它是高度平衡的。对于这个问题,一棵高度平衡的二叉树的定义是:一棵二叉树中每个节点的两个子树的深度相差不会超过1。
样例
样例 1:
输入: tree = {1,2,3}
输出: true
样例解释:
如下,是一个平衡的二叉树。
1
/
2 3
样例 2:
输入: tree = {3,9,20,#,#,15,7}
输出: true
样例解释:
如下,是一个平衡的二叉树。
3
https://www.lintcode.cn/problem/balanced-binary-tree/description