C语言程序设计教程（第三版）课后习题6.4 （Java代码）

解题思路:





注意事项:





参考代码:

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

while (scanner.hasNext()) {

long n = scanner.nextInt();

if (n <= 20) {

long Sn = 0;

long a = 1;

for (int i = 1; i <= n; i++) {

a = a * i;

Sn = Sn + a;

}

System.out.print(Sn);

}

}

}

}