HDU 4002 Find the maximum(欧拉函数)

题目链接

猜了一个结论，题面跟欧拉函数有关系。

 import java.util.*;
 import java.math.*;
 import java.text.*;
 import java.io.*;

 public class Main {

     public static void main(String[] args) {
         Scanner cin = new Scanner(System.in);
         int p[] = new int[1001];
         int prim[] = new int[1001];
         int i, j, num, t;
         BigInteger n, temp;
         BigInteger s[] = new BigInteger[201];
         num = 0;
         for (i = 0; i <= 1000; i++)
             p[i] = 0;
         for (i = 2; i <= 1000; i++) {
             if (p[i] == 0) {
                 prim[num++] = i;
                 for (j = i + i; j <= 1000; j += i) {
                     p[j] = 1;
                 }
             }
         }
         s[0] = BigInteger.valueOf(prim[0]);
         for (i = 1; i < 150; i++) {
             temp = BigInteger.valueOf(prim[i]);
             s[i] = s[i - 1].multiply(temp);

         }
         t = cin.nextInt();
         while (t > 0) {
             n = cin.nextBigInteger();
             for (i = 1; i < num; i++) {
                 if (n.compareTo(s[i]) == -1) {
                     break;
                 }
             }
             System.out.println(s[i-1]);
             t--;
         }
     }
 }