（数论）51NOD 1106 质数检测

 1 #include <stdio.h>
 2 #define MAXN 31623
 3 
 4 int vis[MAXN], pri[MAXN], m = 0;
 5 
 6 void phi()
 7 {
 8     vis[0] = vis[1] = 0;
 9     for (int i = 2; i < MAXN; i++)
10     {
11         if (!vis[i]) pri[m++] = i;
12         for (int j = 0; j < m; j++)
13         {
14             if (i*pri[j] > MAXN) break;
15             vis[i*pri[j]] = 1;
16             if (i%pri[j] == 0) break;
17         }
18     }
19     return;
20 }
21 
22 int main()
23 {
24     int n;
25     phi();
26     while (scanf_s("%d", &n) != EOF)
27     {
28         while (n--)
29         {
30             int temp;
31             scanf_s("%d", &temp);
32             if (temp < MAXN) 
33                 printf("%s\n", vis[temp]? "NO" : "YES");
34             else
35             {
36                 int flag = 0;
37                 for (int j = 0; j < m; j++)
38                     if (temp % pri[j] == 0)
39                     {
40                         flag = 1;
41                         break;
42                     }
43                 printf("%s\n", flag ? "NO" : "YES");
44             }
45         }
46     }
47 }