1 class Solution { 2 public: 3     void help(vector
     
       &a, int now, int sum, int target, vector
      
        &path, vector
       
        
          > &ans, bool last) { 4         if (sum > target) { 5             return ; 6         } 7         if (now >= a.size()) { 8             if (sum == target) { 9                 ans.push_back(path);10             }11             return ;12         }13         if ((now == 0) || (a[now - 1] != a[now]) || last) {14             path.push_back(a[now]);15             help(a, now + 1, sum + a[now], target, path, ans, true);16             path.pop_back();17         }18         help(a, now + 1, sum, target, path, ans, false);19     }20     /**21      * @param num: Given the candidate numbers22      * @param target: Given the target number23      * @return: All the combinations that sum to target24      */25     vector
         
          
            > combinationSum2(vector
           
             &num, int target) {26 // write your code here27 sort(num.begin(), num.end());28 vector
            
              path;29 vector
             
              
                > ans;30 help(num, 0, 0, target, path, ans, true);31 return ans;32 }33 };