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

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 
 5 using namespace std;
 6 
 7 int Prime(int x)
 8 {
 9     int i=2,flag = 1;
10     while(i<=sqrt(double(x)) && flag==1)
11     {
12         if(x%i==0)
13         {
14            flag = 0;
15            break;
16         }
17         i++;
18     }
19     return flag;
20 }
21 
22 int main()
23 {
24     int N, C, i, j;
25     int a[500],count,k;
26     
27     while (cin>>N>>C)
28     {
29         j = 2;
30         a[1] = 1;
31         count = 1;
32         for(i=2; i<=N; i++)
33         {
34             if(Prime(i))
35             {
36                a[j++] = i;
37                count++;
38             }
39         }
40         printf("%d %d:",N,C);
41         if(2*C>count || 2*C-1>count)
42         {
43            for(i=1; i<=count; i++)
44            {
45                printf(" %d",a[i]);
46            }
47         }
48        else
49        {  
50           if(count%2 == 0)
51           {
52              k = count/2;       
53              for(i=k-C+1; i<=k+C; i++)
54              { 
55                 printf(" %d",a[i]);
56              }
57           } 
58           else
59           {
60              k = count/2+1;     
61              for(i=k-C+1; i<=k+C-1; i++)
62              {
63                 printf(" %d",a[i]);
64              }
65          }
66       }
67       printf("\n\n");
68    }
69   return 0;
70 }   
71  
72