BalancedBinaryTree*

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.

Example 1:

Given the following tree [3,9,20,null,null,15,7]:

    3
   / \
  9  20
    /  \
   15   7
   
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 First ,i am surprised it can pass ,because i writed two-layer recursion,i thought it can not pass ,for example time is out 
 i just come up with it 
 
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 class Solution {
public :
	bool isBalanced(TreeNode *root) {
		if (root == NULL) {
			return true;
		}
		if (abs(getHeight(root->left) - getHeight(root->right)) > 1) {
			return false;
		}
		bool leftcount = isBalanced(root->left);
		bool rightcount = isBalanced(root->right);
		
		return leftcount&&rightcount;
	}
	int getHeight(TreeNode* root) {
		if (root == NULL) {
			return 0;
		}
		int t1 = getHeight(root->left);
		int t2 = getHeight(root->right);
		return (t1 > t2 ? t1 : t2) + 1;
	}
};
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