description: Luntik came out for a morning stroll and found an array a of length n. He calculated the sum s of the elements of the array (s= ∑_{i=1}^{n} a_i). Luntik calls a subsequence of the array a nearly full if the sum of the numbers in that subsequence is equal to s-1.
  
  Luntik really wants to know the number of nearly full subsequences of the array a. But he needs to come home so he asks you to solve that problem!
  
  A sequence x is a subsequence of a sequence y if x can be obtained from y by deletion of several (possibly, zero or all) elements.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 1000) — the number of test cases. The next 2 ⋅ t lines contain descriptions of test cases. The description of each test case consists of two lines.
  
  The first line of each test case contains a single integer n (1 ≤ n ≤ 60) — the length of the array.
  
  The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ 10^9) — the elements of the array a.
  
  Output
  
  For each test case print the number of nearly full subsequences of the array.
  
  Example
  
  Input
  
  
  5
  5
  1 2 3 4 5
  2
  1000 1000
  2
  1 0
  5
  3 0 2 1 1
  5
  2 1 0 3 0
  
  
  Output
  
  
  1
  0
  2
  4
  4
  
  Note
  
  In the first test case, s=1+2+3+4+5=15, only (2,3,4,5) is a nearly full subsequence among all subsequences, the sum in it is equal to 2+3+4+5=14=15-1.
  
  In the second test case, there are no nearly full subsequences.
  
  In the third test case, s=1+0=1, the nearly full subsequences are (0) and () (the sum of an empty subsequence is 0).
solution: #include <bits/stdc++.h>
  using namespace std;
  vector<long long> adj1[(long long)1002];
  vector<bool> visit1((long long)1002, false);
  vector<long long> adj2[(long long)1002];
  vector<bool> visit2((long long)1002, false);
  void _print(long long t) { cerr << t; }
  void _print(string t) { cerr << t; }
  void _print(char t) { cerr << t; }
  void _print(long double t) { cerr << t; }
  void _print(double t) { cerr << t; }
  void _print(unsigned long long t) { cerr << t; }
  template <class T, class V>
  void _print(unordered_map<T, V> v) {
    cerr << "[ ";
    for (auto i : v) {
      _print(i);
      cerr << " ";
    }
    cerr << "]";
  }
  template <class T, class V>
  void _print(pair<T, V> p);
  template <class T>
  void _print(vector<T> v);
  template <class T>
  void _print(set<T> v);
  template <class T, class V>
  void _print(map<T, V> v);
  template <class T>
  void _print(multiset<T> v);
  template <class T, class V>
  void _print(pair<T, V> p) {
    cerr << "{";
    _print(p.first);
    cerr << ",";
    _print(p.second);
    cerr << "}";
  }
  template <class T>
  void _print(vector<T> v) {
    cerr << "[ ";
    for (T i : v) {
      _print(i);
      cerr << " ";
    }
    cerr << "]";
  }
  template <class T>
  void _print(set<T> v) {
    cerr << "[ ";
    for (T i : v) {
      _print(i);
      cerr << " ";
    }
    cerr << "]";
  }
  template <class T>
  void _print(multiset<T> v) {
    cerr << "[ ";
    for (T i : v) {
      _print(i);
      cerr << " ";
    }
    cerr << "]";
  }
  template <class T, class V>
  void _print(map<T, V> v) {
    cerr << "[ ";
    for (auto i : v) {
      _print(i);
      cerr << " ";
    }
    cerr << "]";
  }
  void intext() {}
  long long gcd(long long a, long long b) {
    if (b > a) {
      return gcd(b, a);
    }
    if (b == 0) {
      return a;
    }
    return gcd(b, a % b);
  }
  long long expo(long long a, long long b, long long mod) {
    long long res = 1;
    while (b) {
      if (b & 1) res = (res * a) % mod;
      a = (a * a) % mod;
      b >>= 1;
    }
    return res;
  }
  void extendgcd(long long a, long long b, long long *v) {
    if (b == 0) {
      v[0] = 1;
      v[1] = 0;
      v[2] = a;
      return;
    }
    extendgcd(b, a % b, v);
    long long x = v[1];
    v[1] = v[0] - v[1] * (a / b);
    v[0] = x;
    return;
  }
  long long mminv(long long a, long long b) {
    long long arr[3];
    extendgcd(a, b, arr);
    return arr[0];
  }
  long long mminvprime(long long a, long long b) { return expo(a, b - 2, b); }
  bool revsort(long long a, long long b) { return a > b; }
  void swap(long long &x, long long &y) {
    long long temp = x;
    x = y;
    y = temp;
  }
  long long combination(long long n, long long r, long long m,
                        vector<long long> &fact, vector<long long> &ifact) {
    long long val1 = fact[n];
    long long val2 = ifact[n - r];
    long long val3 = ifact[r];
    return (((val1 * val2) % m) * val3) % m;
  }
  void google(long long t) { cout << "Case #" << t << ": "; }
  vector<long long> sieve(long long n) {
    vector<long long> arr(n + 1, true);
    vector<long long> vect;
    for (long long i = 2; i <= n; i++)
      if (arr[i] == 1) {
        vect.push_back(i);
        for (long long j = 2 * i; j <= n; j += i) arr[j] = 0;
      }
    return vect;
  }
  long long mod_add(long long a, long long b, long long m) {
    a = a % m;
    b = b % m;
    return (((a + b) % m) + m) % m;
  }
  long long mod_mul(long long a, long long b, long long m) {
    a = a % m;
    b = b % m;
    return (((a * b) % m) + m) % m;
  }
  long long mod_sub(long long a, long long b, long long m) {
    a = a % m;
    b = b % m;
    return (((a - b) % m) + m) % m;
  }
  long long mod_div(long long a, long long b, long long m) {
    a = a % m;
    b = b % m;
    return (mod_mul(a, mminvprime(b, m), m) + m) % m;
  }
  long long phin(long long n) {
    long long number = n;
    if (n % 2 == 0) {
      number /= 2;
      while (n % 2 == 0) n /= 2;
    }
    for (long long i = 3; i <= sqrt(n); i += 2) {
      if (n % i == 0) {
        while (n % i == 0) n /= i;
        number = (number / i * (i - 1));
      }
    }
    if (n > 1) number = (number / n * (n - 1));
    return number;
  }
  long long binary_expo(long long a, long long b) {
    long long res = 1;
    while (b) {
      if (b & 1) res *= a;
      a *= a;
      b >>= 1;
    }
    return res;
  }
  vector<long long> factor_(long long n) {
    vector<long long> factor;
    for (long long i = 1; i * i <= n; i++) {
      if (n % i == 0) {
        factor.push_back(i);
        if (i != n / i) factor.push_back(n / i);
      }
    }
    return factor;
  }
  signed main() {
    intext();
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    long long tcc;
    cin >> tcc;
    while (tcc--) {
      long long n;
      cin >> n;
      vector<long long> v(n);
      map<long long, long long> mp;
      for (long long i = 0; i < n; i++) {
        cin >> v[i];
        mp[v[i]]++;
      }
      long long ans;
      if (mp[0] != 0)
        ans = binary_expo(2, mp[0]) * mp[1];
      else
        ans = mp[1];
      cout << ans << "\n";
    }
  }
  