HDU2161

解题思路：判断素数模板题。

 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 using namespace std;
 const int maxn = ;
 int vis[maxn];

 void Init()
 {
     memset(vis, , sizeof(vis));
     vis[] = ;
     for(int i = ; i <= maxn; i++)
     {
         for(int j = i+i; j <= maxn; j +=i)
             vis[j] = ;
     }
     return ;
 }
 int main()
 {
     Init();
     int n, kase = ;
     while(~scanf("%d", &n))
     {
         if(n <= ) break;
         if(n ==  || n == )
         {
             printf("%d: no\n", kase++);
             continue;
         }
         if(!vis[n]) printf("%d: yes\n", kase++);
         else printf("%d: no\n", kase++);
     }
     return ;
 }