7.Sum root to leaf numbers

class Solution {
public:
    void  helper(TreeNode* root , vector <int> &ans , vector < vector <int> >&res)
    {
        if(root == NULL)
        {
            return ; 
        }
       
        if(root->right == NULL && root->left == NULL)
        {
            ans.push_back(root->val) ;
            res.push_back(ans) ;
            ans.pop_back() ;
        }
        ans.push_back(root->val) ;
        helper(root->left , ans , res) ; 
        helper(root->right , ans , res ) ;
        ans.pop_back() ;
    } 
    int sumNumbers(TreeNode* root) {
         vector < vector <int> > res ; 
         vector <int> ans ; 
         helper(root , ans , res) ;
         int tsum = 0 ; 
         for(int i = 0 ;  i < res.size() ; i++)
         {
             int s = 0 ; 
             for(int j = 0 ; j < res[i].size() ; j++)
             {

                 s = s * 10 + res[i][j] ;  
             }
             tsum = tsum + s ; 
             //cout << tsum ; 
         }
        return tsum; 
        
    }
};