真因數 => 從1..n/2

建議先寫 d010

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程式碼如下：

import java.util.Scanner;
class c184 {
    static final Scanner in = new Scanner(System.in);
    public static void main(String[] args) {
        boolean bool = true;
        while (bool) {
            int n = in.nextInt();
            if (n == 0) {
                bool = false;
                break;
            }
            if (num(n) == n) {
                System.out.println("=" + n);
            } else if (num(num(n)) == n) {
                System.out.println(num(n));
            } else {
                System.out.println(0);
            }
        }
    }
    static int num(int n) {
        int res = 0;
        for (int i = 1; i <= n / 2; i++) {
            if (n % i == 0) res += i;
        }
        return res;
    }
}