【LeetCode】110. Balanced Binary Tree

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 1.

递归来做很简单。

一棵树要满足平衡条件必须同时满足以下三个全部条件：

1、左子树满足平衡条件

2、右子树满足平衡条件

3、左右子树深度差不超过1

/**
 * Definition for binary tree
 * 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;
        return isBalanced(root->left) && isBalanced(root->right) && (abs(maxDepth(root->left)-maxDepth(root->right))<=1);
    }
    int maxDepth(TreeNode* root)
    {
        if(!root)
            return 0;
        else
            return 1+max(maxDepth(root->left), maxDepth(root->right));
    }
};