Balanced Binary Tree

发表于   |   分类于 ， ，

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.

描述

给出一棵二叉树，判断是否为平衡二叉树

分析

在求二叉树深度的过程中，判断左右子树是否满足

代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {

    public boolean isBalanced(TreeNode root) {

        return height(root) != -1;
    }

    private int height(TreeNode root) {

        if (root == null) {
            return 0;
        }

        int l = height(root.left);
        int r = height(root.right);

        if (Math.abs(l - r) > 1 || l == -1 || r == -1) {
            return -1;
        }

        return Math.max(l, r) + 1;
    }
}