[LeetCode]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.

思考：求二叉树高的变形，加上判断即可。

/**

 * Definition for binary tree

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

private:

    bool flag;

public:

    int DFS(TreeNode *root)

    {

        if(root)

        {

            int height1=DFS(root->left);

            int height2=DFS(root->right);

            if(abs(height1-height2)>1) flag=false;

            return max(height1,height2)+1;

        }

        else return 0;

    }

    bool isBalanced(TreeNode *root) {

        flag=true;

        int height=DFS(root);//树高

        return flag;

    }

};