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: 
  import java.io.*;
          import java.util.Stack;
          import java.util.Queue;
          import java.util.*;
  public class Solver {
      public static void main(String[] args) throws IOException {
          Deque<Integer> bl = new LinkedList<>();
          Deque<String> temp = new LinkedList<>();
          int t=nextInt();
          for (int i = 0; i <t; i++) {
              int n=nextInt();
              int a[]=new int[n];
              long s=0;
              long ans=0;
              for (int j = 0; j < n; j++) {
                  a[j] = nextInt();
                  if (a[j] == 1) {
                      s = 1;
                  }
              }
              if(s==1) {
                  int cnt=0;
                  s=0;
                  for (int j = 0; j <n; j++) {
                      if(a[j]==1){
                          s++;
                      }else if(a[j]==0){
                          cnt++;
                      }
                  }
                  for (int j = 0; j <cnt ; j++) {
                      s=s*2;
                  }
                  ans=s;
              }
              out.println(ans);
          }
          out.close();
      }
      static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      static PrintWriter out = new PrintWriter(System.out);
      static StringTokenizer in = new StringTokenizer("");
      static class Student implements Comparable<Student>{
          long a;
          long temp;
          Student(long a,long temp) {
              this.a = a;
              this.temp=temp;
          }
          public int compareTo(Student other) {
              return Long.compare(this.a,other.a);
          }
      }
      public static boolean hasNext() throws IOException {
          if (in.hasMoreTokens()) return true;
          String s;
          while ((s = br.readLine()) != null) {
              in = new StringTokenizer(s);
              if (in.hasMoreTokens()) return true;
          }
          return false;
      }
      public static String nextToken() throws IOException {
          while (!in.hasMoreTokens()) { in = new StringTokenizer(br.readLine()); }return in.nextToken();
      }
      public static int nextInt() throws IOException { return Integer.parseInt(nextToken());
      }
      public static double nextDouble() throws IOException { return Double.parseDouble(nextToken());
      }
      public static long nextLong() throws IOException { return Long.parseLong(nextToken());
      }
  }