686 - Goldbach's Conjecture (II)

import java.util.*;

public class Main2 {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        boolean[] primeList = new boolean[33000];
        primeList[2] = true;
        primeList[3] = true;
        for (int i=4;i<33000;i++) {
            primeList[i] = isPrime(i);
        }
        while (scanner.hasNextInt()) {
            int num = scanner.nextInt();
            if (num == 0) break;
            int counter = 0;
            for (int i=2;i<=num/2;i++) {
                if (primeList[i] && primeList[num-i]) counter++;
            }

            System.out.println(counter);
        }
    }

    static boolean isPrime(int num) {
        for (int i=2;i<=num/2;i++) {
            if (num%i == 0) return false;
        }
        return true;
    }
}