牛客寒假算法基础集训营2 处女座的测验（一） （数论+构造）

 1 import java.util.Scanner;
 2  
 3 public class Main { 
 4     static final int maxn = 1000005;
 5     static long [] prime = new long [maxn];
 6     static int [] book = new int [maxn];
 7     static int cnt = 0;
 8     static void getprime() {
 9         for(int i=2;i<maxn;i++) {
10             if(book[i]==0) {
11                 prime[cnt++] = (long)i;
12                 if(cnt>4000)
13                     break;
14                 for(int j=i+i;j<maxn;j+=i) {
15                     book[j] = 1;
16                 }
17             }
18         }
19     }
20     public static void main(String[] args) {
21         Scanner cin = new Scanner(System.in);
22         getprime();
23         
24         for(int i=0;i<cnt/2;i++) {
25             System.out.println(prime[i]*prime[cnt-1-i]);
26         }
27     }
28 }