编写一个java应用程序，在键盘上输入数20，计算并输出1！+2！+..+n！的结果。

Question

如题所述

Answer 1

用递归实现：
定义main.java:
public static void main(String[] args)

{
System.out.println("Please enter a positive integer");
Scanner x=new Scanner(System.in);
int f=x.nextInt();
for (int i = 1; i < f; i++) {
System.out.println("第"+ i+"个累加因素，和是："+ sum_fac(i, 1));
}
}
private static int sum_fac(int target, int counter) {
return (target == counter) ? target : counter * (1 + sum_fac(target, counter + 1));
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