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         pair<bool,int> res = isOk(root);14         return res.first;15     }16     pair<bool,int> isOk(TreeNode *root){17         if(root == NULL){18             return make_pair(true,0);19         }20         pair<bool,int> left = isOk(root->left);21         pair<bool,int> right = isOk(root->right);22         bool balanced = left.first&&right.first;23         if(abs(left.second-right.second) > 1){24             balanced = false;25         }26         int height = max(left.second,right.second)+1;27         return make_pair(balanced,height);28     }29 };