站在巨人肩膀上的答案

一般遇到判断质数的题，样例往往会有个特别大的质数，所以for遍历的时候要遍历sqrt(num)；

import java.util.*;
public class Main{
public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long num = sc.nextInt();
    long sqr = (long)Math.sqrt(num);
    for (long i = 2; i <= sqr; ++i) {
        while (num % i == 0) {
            System.out.print(i + " ");
            num /= i;
        }
    }
    if(num != 1)
        System.out.println(num);
}
}