【leetcode】Balanced Binary Tree

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.

题解：一A的题，写一个递归函数height计算树的高度，然后递归实现isBalance函数即可。代码如下：

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isBalanced(TreeNode *root) {
13         if(root == NULL)
14             return true;
15         if(abs(height(root->left)-height(root->right)) > 1)
16             return false;
17         return isBalanced(root->left) && isBalanced(root->right);
18     }
19     int height(TreeNode *root){
20         if(root == NULL)
21             return 0;
22         int left = height(root->left);
23         int right = height(root->right);
24         return 1+(left>right?left:right);
25     }
26 };