20. 求阶乘序列前N项和

求阶乘序列前N项和

#include <stdio.h>
double fact(int n);

int main()
{
    int i, n;
    double item, sum;
    while (scanf("%d", &n) != EOF)
    {
        sum = 0;
        if (n <= 12)
        {
            for (i = 1; i <= n; i++)
            {
                item = fact(i);
                sum = sum + item;
            }
        }
        printf("%.0f\n", sum);
    }
    return 0;
}

double fact(int n)
{
    int i;
    double product;
    product = 1;
    for (i = 1; i <= n; i++)
    {
        product = product*i;
    }
    return product;
}