poj2635

高精度，java快要忘没了。java使用文件输入要抛出异常。

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

public class Main {
    static int[] prm = new int[1000000];
    static boolean[] is = new boolean[1000000];

    static int getprm(int n) {
        int i, j, k = 0;
        int s, e = (int) (Math.sqrt(0.0 + n) + 1);
        for (i = 0; i < 1000000; i++)
            is[i] = true;
        prm[k++] = 2;
        is[0] = is[1] = false;
        for (i = 4; i < n; i += 2)
            is[i] = false;
        for (i = 3; i < e; i += 2)
            if (is[i]) {
                prm[k++] = i;
                for (s = i * 2, j = i * i; j < n; j += s)
                    is[j] = false;
                // 因为j是奇数,所以+奇数i后是偶数,不必处理!
            }
        for (; i < n; i += 2)
            if (is[i])
                prm[k++] = i;
        return k;
        // 返回素数的个数
    }

    public static void main(String args[]) throws FileNotFoundException {
        Scanner cin = new Scanner(new BufferedInputStream(System.in));
        //Scanner cin =new Scanner (new FileInputStream("t.txt"));
        String st;
        int count = getprm(1000000);
        boolean found = false;
        BigInteger zero = new BigInteger("0");
        while (cin.hasNext()) {
            st = cin.next();
            found = false;
            BigInteger a = new BigInteger(st);
            int b = cin.nextInt();
            if (a.equals(zero) && b == 0)
                break;
            for (int i = 0; i < count && prm[i] < b; i++)
                if (a.mod(BigInteger.valueOf(prm[i])).equals(zero)) {
                    System.out.println("BAD " + prm[i]);
                    found = true;
                    break;
                }
            if (!found)
                System.out.println("GOOD");
        }
    }
}