LeetCode:balanced binary tree

 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) return true;
14         if(root->left==NULL && root->right==NULL) return true;
15         if(abs(getHeight(root->left)-getHeight(root->right)) > 1) return false;
16         return isBalanced(root->left) && isBalanced(root->right);
17     }
18     int getHeight(TreeNode *node){
19         if(node==NULL) return 0;
20         else
21         {
22             int i=getHeight(node->left);
23             int j=getHeight(node->right);
24             return i>j?i+1:j+1;
25         }
26         
27     }
28 };