题目描述

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.

思路

判断一棵树是不是平衡二叉树，递归的求每个结点的左子树和右子树的树高，判断左子树和右子树的高度之差不超过1

代码实现

class Solution
{
public:
    bool isBalanced(TreeNode *root)
        {
            return balancedHeight (root)>=0;
        }
        int balancedHeight (TreeNode* root)
        {
            if  (root==NULL)      return 0;
            int left=balancedHeight (root->left);
            int right=balancedHeight(root->right);

            if(left<0 || right<0 ||abs(left - right)>1)   return -1;

            return max(left,right)+1;
        } 
};