/**
* 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 check(root) != -1;
}
int check(TreeNode* node) {
if (node == NULL) return 0;
int levl = check(node->left);
int revl = check(node->right);
if (dis(levl - revl) > 1 || levl == -1 || revl == -1) {
return -1;
}
return (levl > revl ? levl : revl) + 1;
}
int dis(int i) {
return i < 0 ? -i : i;
}
};