ZOJ 1312 题解这是一道简单题但容易出错，不需要使用任和算法就可做出来，而且很快。我的AC 0ms

#include<cstdio>
#include<iostream>
#include<cmath>

using namespace std;

int Prime(int x)
{
    int i=2,flag = 1;
    while(i<=sqrt(double(x)) && flag==1)
    {
        if(x%i==0)
        {
           flag = 0;
           break;
        }
        i++;
    }
    return flag;
}

int main()
{
    int N, C, i, j;
    int a[500],count,k;
    
    while (cin>>N>>C)
    {
        j = 2;
        a[1] = 1;
        count = 1;
        for(i=2; i<=N; i++)
        {
            if(Prime(i))
            {
               a[j++] = i;
               count++;
            }
        }
        printf("%d %d:",N,C);
        if(2*C>count || 2*C-1>count)
        {
           for(i=1; i<=count; i++)
           {
               printf(" %d",a[i]);
           }
        }
       else
       {  
          if(count%2 == 0)
          {
             k = count/2;       
             for(i=k-C+1; i<=k+C; i++)
             { 
                printf(" %d",a[i]);
             }
          } 
          else
          {
             k = count/2+1;     
             for(i=k-C+1; i<=k+C-1; i++)
             {
                printf(" %d",a[i]);
             }
         }
      }
      printf("\n\n");
   }
  return 0;
}