vector<vector<int>> v;

    void f(int i, int tar, vector<int>& nums, vector<int>& can) {
        if ( tar == 0) {
            v.push_back(nums);
            return;
        }
        if (i == can.size() || tar < 0)
            return;
     

        nums.push_back(can[i]);
        f(i, tar - can[i], nums, can);
        nums.pop_back();

        f(i + 1, tar, nums, can);
        
    }

    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        vector<int> ds;
        f(0, target, ds, candidates);
        return v;
    }