/**

 * 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:

    vector<int> findFrequentTreeSum(TreeNode* root) {

        vector<int> res;

        int cnt=0;

        unordered_map<int,int> m;

        postorder(root,m,cnt,res);

        return res;

    }

    int postorder(TreeNode* node,unordered_map<int,int> &m,int &cnt,vector<int> &res)

    {

        if(!node)

        {

            return 0;

        }

        int left=postorder(node->left,m,cnt,res);

        int right=postorder(node->right,m,cnt,res);

        int sum=left+right+node->val;

        ++m[sum];

        if(m[sum]>=cnt)

        {

            if(m[sum]>cnt)

            {

                res.clear();

            }

            res.push_back(sum);;

            cnt=m[sum];

        }

        return sum;

    }

};