Question

Link : https://leetcode.com/problems/balanced-binary-tree/

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

Code

一个比较挫的版本。（C++ ： 28ms）

/**
 * 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 == NULL)
            return true;

        int sub = abs(height(root->left) - height(root->right));
        if(sub > 1)
            return false;

        return isBalanced(root->left) && isBalanced(root->right);
    }

    int height(TreeNode* root){
        if (root == NULL)
            return 0;
        int lhs = height(root->left);
        int rhs = height(root->right);
        return 1 + (lhs > rhs ? lhs : rhs);
    }
};