class Solution {
    vector<vector<int>>ans;
    void fun(int i, int n , int target , vector<int>&a , vector<int>tp)
    {
        if(target < 0) return;
        if(target == 0)
        {
            ans.push_back(tp);
            return ;
        }
        if(i == n-1)
        {
           if(target % a[i] == 0)
           {
               int times = target/a[i];
               while(times>0)
               {
                   tp.push_back(a[i]); times--;
               }
               ans.push_back(tp);
           }
           return ;
        }
        tp.push_back(a[i]); fun(i,n,target - a[i],a,tp);
        tp.pop_back();
        fun(i+1,n,target,a,tp);
    }
public:
    vector<vector<int>> combinationSum(vector<int>& a, int target) {
        int n = a.size();
        vector<int>tp;
        fun(0,n,target,a,tp);
        return ans;
    }
};