题解 | #质数因子#--利用递归方法

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            int num = in.nextInt();
            // 利用递归方法
            getPrime(num);
        }
    }

    // 获取质数因子
    private static void getPrime(int num) {
        if (isPrime(num)) {
            System.out.print(num + " ");
        }
        int sqrt = (int) Math.sqrt(num);
        // 是否能被小于等于sqrt的数整除
        for (int i = 2; i <= sqrt; i++) {
            if (num % i == 0) {
                System.out.print(i + " ");
                // 判断是否是质数
                if (isPrime(num / i)) {
                    System.out.print(num / i + " ");
                    break;
                }
                getPrime(num / i);
                break;
            }
        }
    }

    private static boolean isPrime(int num) {
        if (num <= 3) {
            return true;
        }
        int sqrt = (int) Math.sqrt(num);
        for (int i = 2; i <= sqrt; i++) {
            if (num % i == 0) {
                return false;
            }
        }
        return true;
    }
}