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.
地址：https://oj.leetcode.com/problems/balanced-binary-tree/
算法：递归解决，并且在递归的过程中求出树的深度。代码：
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){
14 return true;
15 }
16 int depth = 0;
17 return subIsBalanced(root,depth);
18 }
19 bool subIsBalanced(TreeNode *root, int &depth){
20 if(!root){
21 depth = 0;
22 return true;
23 }
24 int left_depth;
25 bool left = subIsBalanced(root->left,left_depth);
26 int right_depth;
27 bool right = subIsBalanced(root->right,right_depth);
28 depth = left_depth > right_depth ? left_depth + 1 : right_depth + 1;
29 if(left && right){
30 if(left_depth > right_depth + 1 || right_depth > left_depth + 1){
31 return false;
32 }
33 return true;
34 }
35 return false;
36 }
37 };