Untitled

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)

Problem Description

There is an integer a and n integers b1,…,bn.
After selecting some numbers from b1,…,bn in
any order, say c1,…,cr,
we want to make sure that a mod c1 mod c2 mod… mod cr=0 (i.e., a will
become the remainder divided by ci each
time, and at the end, we want a to
become 0).
Please determine the minimum value of r.
If the goal cannot be achieved, print ?1 instead.

Input

The first line contains one integer T≤5,
which represents the number of testcases.

For each testcase, there are two lines:

1. The first line contains two integers n and a (1≤n≤20,1≤a≤106).

2. The second line contains n integers b1,…,bn (?1≤i≤n,1≤bi≤106).

Output

Print T answers
in T lines.

Sample Input

2
2 9
2 7
2 9
6 7

Sample Output

2
-1

Source

BestCoder Round #49 ($)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int INF=0x3f3f3f3f;

int n,a;
int b[30];

int main()
{
  int T_T;
  scanf("%d",&T_T);
  while(T_T--)
    {
      scanf("%d%d",&n,&a);
      for(int i=0;i<n;i++)
        {
          scanf("%d",b+i);
        }
      sort(b,b+n,greater<int>());

      int ans=INF;
      for(int i=0;i<(1<<n);i++)
        {
          int ta=a;
          int cnt=0;
          for(int j=0;j<n;j++)
            {
              if((i>>j)&1)
                {
                  cnt++;
                  ta%=b[j];
                }
            }
          if(ta==0)
            {
              ans=min(ans,cnt);
            }
        }
      if(ans==INF) ans=-1;
      printf("%d\n",ans);
    }
  return 0;
}

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