class Solution {

 public:

     vector<vector<int>> subNumbers(TreeNode *root) {

         vector<vector<int>> sums;

         if(root == NULL)

             return sums;

         if(root->left == NULL && root->right == NULL){

             vector<int> seq;

             seq.push_back(root->val);

             sums.push_back(seq);

             return sums;

         }

         vector<vector<int>> left_sums = subNumbers(root -> left);

         for(auto item: left_sums) {

             item.insert(item.begin(), root->val);

             sums.push_back(item);

         }

         vector<vector<int>> right_sums = subNumbers(root -> right);

         for(auto item: right_sums) {

             item.insert(item.begin(), root->val);

             sums.push_back(item);

         }

         return sums;

     }

     int pow10(int n) {

         int ret = ;

         for(int i = ; i < n; i++)

             ret = ret * ;

         return ret;

     }

     int sumNumbers(TreeNode *root) {

         // Note: The Solution object is instantiated only once and is reused by each test case.

         int sum = ;

         vector<vector<int>> sums = subNumbers(root);

         for(auto v : sums){

             int tmp_sum = ;

             for(int i = v.size() - ; i >= ; i -- ) {

                 tmp_sum += v[i] * pow10(v.size() -  - i);

             }

             sum += tmp_sum;

         }

         return sum;

     }

 };