1582B - Luntik and Subsequences - CodeForces Solution

#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define loop(i,a,n) for(int i = a; i <= n; i++)
#define loopr(i,n,a) for(int i = n; i >= a; i--)
#define foor(i,n) for(int i = 0; i < n; i++)
#define fore(el,v) for(auto& el:v)
#define cin(v) for(auto& el:v) cin>>el;
#define cout(v) for(auto el:v) cout<<el<<" "; cout<<'\n';
#define undirected(m) for(int iii=0;iii<m;iii++){int aaa,bbb;cin >> aaa >> bbb;adj[aaa].push_back(bbb);adj[bbb].push_back(aaa);}
#define directed(m) for(int iii=0;iii<m;iii++){int aaa,bbb;cin >> aaa >> bbb;adj[aaa].push_back(bbb);}
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
#define YES cout << "YES\n";
#define NO cout << "NO\n";
#define Ones(n) __builtin_popcount(n)
#define Onesll(n) __builtin_popcountll(n)
#define PI acos(-1)
#define sin(a) sin((a)*PI/180)
#define cos(a) cos((a)*PI/180)
#define tan(a) tan((a)*PI/180)
#define fast ios::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);
#define endl '\n'

using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pi = pair<int,int>;
using pll = pair<ll,ll>;
using tiii = tuple<int,int,int>;
using tlll = tuple<ll,ll,ll>;
using vi = vector<int>;
using vb = vector<bool>;
using vll = vector<ll>;
using vpi = vector<pair<int,int>>;
using vvi = vector<vector<int>>;
using mii = map<int,int>;

const int MOD = 1e9+7;
const int OO = 2e9;
const int N = 1e6+5, M = 1e3+5, LG = 20;

ll powmod(ll x, ll y)
{
    x %= MOD;
    ll ans = 1;
    while(y)
    {
        if(y & 1) ans = ans * x % MOD;
        x = x * x % MOD;
        y >>= 1;
    }
    return ans;
}

ll fact[N], modInv[N];

void preprocess(){
    fact[0] = 1;
    loop(i,1,N-1){
        fact[i] = (fact[i-1] * i)%MOD;
    }
    modInv[N-1] = powmod(fact[N-1], MOD-2);
    loopr(i,N-2,0){
        modInv[i] = (modInv[i+1] * (i+1)) %MOD;
    }
}

ll nCr(int n,int r) {
    if (r > n)
        return 0;
    // return ( n! / ((n-r)! * r!) ) % mod
    return (((fact[n] * modInv[n - r]) % MOD) * modInv[r]) % MOD;
}

ll add(ll a, ll b) {
    a += b;
    if (a >= MOD) a -= MOD;
    return a;
}
ll sub(ll a, ll b) {
    a -= b;
    if (a < 0) a += MOD;
    return a;
}
ll mul(ll a, ll b) {
    return a * b % MOD;
}
ll inv(ll a) {
    return powmod(a, MOD - 2);
}

ll fastpow(ll b, ll p) {
    if (!p) return 1;
    ll ret = fastpow(b, p >> 1);
    ret *= ret;
    if (p & 1)
        ret *= b;
    return ret;
}


void TC()
{
    int n;
    cin >> n;
    ll x,l=0,o=0;
    foor(i,n){
        cin >> x;
        if(x==0) o++;
        else if(x==1) l++;
    }
    cout << fastpow(2,o) * l;
}

int32_t main()
{
#ifndef ONLINE_JUDGE
    freopen("input.in", "r", stdin); freopen("output.out", "w", stdout);
#endif
    fast
    int t = 1;
    cin >> t;
//    preprocess();
    while (t--)
    {
        TC();
        cout << '\n';
    }
    return 0;
}