[编程入门]阶乘求和-题解(Java代码)

import java.util.Scanner;
/*注意：这里需要用long,int可能精度不够*/
public class Main {
public static void main(String[] args) {
    Scanner sc=new Scanner(System.in);
    long n=sc.nextInt();
    if (n>20) {
        return;
    }
    long sn=0;
    for (long i = 1; i <=n; i++) {
        long sum=1;
        for (long j = 1; j <=i; j++) {
            sum*=j;
        }
        sn+=sum;
    }
    System.out.println(sn);
}
}