Day34: [LeetCode简单] 110. 平衡二叉树

题源：

来自leetcode题库：

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

代码：

dirty code凑合看吧

/**
 * 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 flag;
    int f(TreeNode* root){
        if(flag==false) return -1;
        if(root){
            int x=f(root->left),y=f(root->right);
            if(x-y>1||y-x>1) flag=false;
            return (x>y?x:y)+1;
        }else{
            return 0;
        }
    }
    bool isBalanced(TreeNode* root) {
        if(!root) return 1;
        flag=true;
        f(root);
        return flag;
    }
};