count no.of subsequences with sum==k

#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<string,int> psi;
typedef unordered_map<int,int> mii;
typedef unordered_map<long long,long long> mll;
typedef unordered_map<string,int> msi;
typedef unordered_map<char,int> mci;
typedef unordered_set<int> si;
typedef unordered_set<long long> sll;
typedef unordered_set<string> ss;
typedef unordered_set<char> sc;
typedef map<int,int> ormii;
typedef map<long long,long long> ormll;
typedef map<string,int> ormsi;
typedef map<char,int> ormci;
typedef set<int> orsi;
typedef set<long long> orsll;
typedef set<string> orss;
typedef set<char> orsc;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<ll> vll;
typedef vector<vector<int>> vvi;
typedef vector<vector<string>> vvs;
typedef vector<vector<ll>> vvll;

#define FOR(i, a, b) for (auto i=a; i<=(b); i++)
#define FORd(i,b,a) for (int i =b; i >= a; i--)
#define sortinc(v)  sort(v.begin(),v.end())
#define sortdec(v)  sort(v.rbegin(),v.rend())
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define pob pop_back
#define fi first
#define se second
#define ins insert

const int MOD = 1000000007;
//type functions here
int  recurr(vi &v,int idx,int sum,int k)
{
    if(idx==v.size()){
        if(sum==k){
            return 1;
        }
        return 0;
    }

       int l,r;
        l=recurr(v,idx+1,sum+v[idx],k);

        r=recurr(v,idx+1,sum,k);

        return l+r;
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int tc=1;
    //cin>>tc;
    FOR(w,1,tc)
    {
       vi v={1,2,3},temp;
       int k=3;
       int c=recurr(v,0,0,k);
       cout<<c;
    }
    return 0;
}