void combinationSumUtils(int indx, int sum, vector<int> &candidates, vector<int> &solution, vector<vector<int> > &result) {

if(sum == 0) {

result.push_back(solution);

return;

}

if(sum < 0) {

return;

}

for(int i = indx; i < candidates.size(); ++i) {

if(candidates[i] > sum) { break; }

solution.push_back(candidates[i]);

combinationSumUtils(i, sum - candidates[i], candidates, solution, result);

solution.pop_back();

}

}

vector<vector<int> > combinationSum(vector<int> &candidates, int target) {

vector<vector<int> > result;

vector<int> solution;

if(candidates.empty()) return result;

sort(candidates.begin(), candidates.end());

combinationSumUtils(0, target, candidates, solution, result);

return result;

}