class Solution {
public:
vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
vector<vector<int>> res;
vector<int> out;
DFS(candidates, target, 0, out, res);
return res;
}
void DFS(vector<int>& candidates, int target, int start, vector<int>& out, vector<vector<int>>& res){
if(target < 0) return;
if(target == 0){
res.push_back(out);
return;
}
for(int i = start; i < candidates.size(); i++){
out.push_back(candidates[i]);
DFS(candidates, target - candidates[i], i, out, res);
out.pop_back();
}
}
};