题解 | #质数因子#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            int num = sc.nextInt();
            if(num < 2){//如果输入的数字小于2则不能进行质因子分解
                return;
            }
            int factor = 2;
            int maxFactor = (int)Math.sqrt(num);//只需要测试到sqrt(num)即可
            while(factor <= maxFactor){
                if (num % factor == 0) {
                    System.out.print(factor + " ");
                    num /= factor;
                    maxFactor = (int)Math.sqrt(num);
                } else {
                    factor++;
                }
            }
            if(num > 1) {
                System.out.print(num);
            }
        }
    }
}