算法-求n的阶乘相加

/*计算阶乘：N!+（N-1）!+(N-2)!.....1*/
public class Code02Factorial {

    public static void main(String[] args) {
        int n = 4;
        factorial(n);
    }

    private static void factorial(int n) {
        long sum = 0; //所以阶乘求和的数
        long fac = 1;  //当前数的阶乘

        for (int i = 1; i <= n; i++) {
            fac = fac * i;
            sum = sum + fac;
        }

        System.out.println(n + "的阶乘之和是：" + sum);

    }


}

运行效果