hdu 5391 Zball in Tina Town (素数的判断）

Problem Description

Tina Town is a friendly place. People there care about each other.
Tina has a ball called zball. Zball is magic. It grows larger every day. On the first day, it becomes

Input

The first line of input contains an integer

Output

For each test case, output an integer representing the answer.

Sample Input

2

3

10

Sample Output

2

0

题意：求从1乘到n-1模n的结果。

只要判断n是否是素数，如果是就输出n-1,否则输出0。n=4，不满足这规律，要特判。

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<map>
 4 #include<cmath>
 5 using namespace std;
 6 int zj[100000];
 7 int ssb[100000];
 8 int pn;
 9 void p()
10 {
11     int i,j;
12     zj[1]=0;
13     zj[0]=0;
14     pn=0;
15     for (i=2;i<=100000;i++)
16     {
17         if (!zj[i]) ssb[pn++]=i;
18         for (j=0;j<pn;j++)
19         {
20             if (i*ssb[j]>100000) break;
21             zj[i*ssb[j]]=1;
22             if (i%ssb[j]==0) break;
23         }
24     }
25 }
26 int main()
27 {
28     p();
29     int n,m,t,i,flag;
30     scanf("%d",&t);
31     while (t--)
32     {
33         flag=0;
34         scanf("%d",&n);
35         if (n==3||n==4) {printf("2\n");continue;}
36         if (n<=100000)
37         {
38             if (zj[n]) printf("0\n");
39             else printf("%d\n",n-1);
40             continue;
41         }
42         flag=0;
43         for (i=0;i<pn;i++)
44         {
45             if (ssb[i]*ssb[i]>n||flag) break;
46             if (n%ssb[i]==0) flag=1;
47         }
48         if (flag) printf("0\n");
49         else printf("%d\n",n-1);
50     }
51 }

posted on 2015-08-16 11:09 pb2016 阅读(373) 评论(0) 编辑收藏举报