#include <bits/stdc++.h>
using namespace std;
void f(vector<int>&v,vector<int>&ds,int idx, int sum, int k, int& cnt){
	if(idx>=v.size() || sum==k){
		if(sum==k)
		{cnt++; return;}
		return;
	}
	sum=sum+v[idx]; ds.push_back(v[idx]);
	f(v,ds,idx+1,sum,k,cnt);
	sum=sum-v[idx]; ds.pop_back();
	f(v,ds,idx+1,sum,k,cnt);
}
int main() {
	vector<int>v= {3,1,2};
	vector<int>ds; int sum=0; int idx=0; int k=6; int cnt=0;
	f(v,ds,idx,sum,k,cnt);
	cout<<" count is "<<cnt<<endl;
}

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