HDOJ 5339 Untitled 水

Untitled

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 481    Accepted Submission(s): 245

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;
}