Combination Sum

/*

Combination Sum

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
The same repeated number may be chosen from C unlimited number of times.
Note:

• All numbers (including target) will be positive integers.
• Elements in a combination (a₁, a₂, � , a_k) must be in non-descending order. (ie, a₁ ? a₂ ? � ? a_k).
• The solution set must not contain duplicate combinations.

For example, given candidate set 2,3,6,7 and target 7,
A solution set is:
[7]
[2, 2, 3]

*/
class Solution {
public:
    vector<vector<int>> findSum(vector<int> candidates, int size, int target){
       vector<vector<int>> result;
       if(size==-1) return result;
       result = findSum(candidates, size-1, target);
       int elem = candidates[size];
       int num;
       vector<int> newComb;
       if(elem > target) return result;
      
       num = target/elem;
       if(target%elem == 0){
          newComb.insert(newComb.begin(), num, elem);
          result.push_back(newComb);
       }
       vector<vector<int>> inter;
      
       int j;
       int i;
       for(j=1; j<=num; j++){
       inter = findSum(candidates, size-1, target-j*elem);
       for(i=0; i<inter.size(); i++){
         inter[i].insert(inter[i].begin()+inter[i].size(), j, elem);
       }
       result.insert(result.begin()+result.size(), inter.begin(), inter.end());
       }
      
       return result;
    }
    vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int>> result;
        if(target<=0) return result;
        int size = candidates.size();
        int i;
        set<int> inter;
        for(i=0; i<size; i++){
         inter.insert(candidates[i]);
        }
        candidates.clear();
        set<int>::iterator it;
        for(it=inter.begin(); it!=inter.end(); it++){
         candidates.push_back(*it);
        }
        return  findSum(candidates, size-1, target);
    }
};