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：

首先明确高度平衡二叉树的定义，利用递归的思路即左右子节点的高度不超过1

代码：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    bool isBalanced(TreeNode* root) {        return Trueorfalse(root)>=0?true:false;            }private:     static int Trueorfalse(TreeNode* root){        if(root==NULL)            return 0;        int leftDepth = Trueorfalse(root->left);        int rightDepth = Trueorfalse(root->right);        if(leftDepth<0||rightDepth<0||abs(leftDepth-rightDepth)>1)            return -1;        return max(leftDepth,rightDepth)+1;    }};