【Balanced Binary Tree】cpp

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.

代码：

/**
 * 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)
        {
            if (!root) return true;
            if ( abs(Solution::height(root->left)-Solution::height(root->right)) <= 1 )
            {
                return Solution::isBalanced(root->left) && Solution::isBalanced(root->right);
            }
            else
            {
                return false;
            }
        }
        static int height(TreeNode* p)
        {
            if (!p) return 0;
            return max(Solution::height(p->left),Solution::height(p->right))+1; 
        }
};

tips：

第一次刷这leetcode把此题漏掉了。

注意balanced tree是指every node：

（1）判断每个节点left和right深度是否相等

（2）再判断left和right分别是不是balanced的