计算阶乘和怎么写教练

Question

Answer 1

#include <stdio.h>
int main()
{
    int i,n;
    double r = 1,s = 0;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        r*=i;
        s += r;
    }
    printf("%g",s);
    return 0;
}