Balanced Binary Tree(LeetCode)

题目：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.

示例代码如下：

class Solution {
public:
    bool isBalanced(TreeNode *root) {
        if(root==NULL)
			return true;
		int lheight=BinaryTreeHeight(root->left);//求左子树高度
		int rheight=BinaryTreeHeight(root->right);//求右子树高度
		if(abs(lheight-rheight)>1)//如果高度差绝对值大于1，返回false
			return false;
		else //判断左右子树是否是平衡二叉树
			return isBalanced(root->left)&&isBalanced(root->right);
    }
	//求二叉树的高度
	int BinaryTreeHeight(TreeNode* root){
		if(root==NULL)
			return 0;
		int lheight=BinaryTreeHeight(root->left);
		int rheight=BinaryTreeHeight(root->right);
		return lheight>rheight ? lheight+1:rheight+1;
	}
};