public class jieSum {
    public static void main(String[] args){
        double sum=0;double k=1;
        for(int i=1;i<=20;i++){
            k=1;
            for(int j=1;j<=i;j++) {
                k*=j;
            }
 

            sum+=1/k;
        }
        System.out.printf("%f",sum);
    }
}

---

相關推薦