leetcode--Balanced Binary Tree

1.题目描述

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.

2.解法分析

判断一个树是否为平衡二叉树与求树的深度如出一辙，只是返回值有两个，一个是当前树是否为平衡二叉树，另一个是当前树的高度。

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isBalanced(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(!root)return true;

        int depth;

        return myJudge(root,depth);
    }

    bool myJudge(TreeNode *root,int &depth)
    {
        if(root==NULL)
        {
           depth=0;return true;
        }

        int depth_left;
        int depth_right;

        bool lj=myJudge(root->left,depth_left);
        if(!lj)return false;
        bool rj=myJudge(root->right,depth_right);
        if(!rj)return false;

        depth = max(depth_left,depth_right)+1;

        if((depth-1-min(depth_left,depth_right))<=1)return true;
        else return false;


    }
};