HDU 1012 u Calculate e

水题~

Problem Description

A simple mathematical formula for e is



where n is allowed to go to infinity. This can actually yield very accurate approximations of e using relatively small values of n.

 

 

Output

Output the approximations of e generated by the above formula for the values of n from 0 to 9. The beginning of your output should appear similar to that shown below.

 

 

Sample Output

n e

- -----------

0 1

1 2

2 2.5

3 2.666666667

4 2.708333333

#include<stdio.h>

__int64 func(int n)
{
    int i, s=1;
    if (n == 0)
        return 1;
    else
    {
        for (i=1; i<=n; i++)
        {
            s*=i;
        }
        return s;
    }
}

int main()
{
    int i, j;
    double e;
    printf("n e\n");
    printf("- -----------\n");
    printf("0 1\n");
    printf("1 2\n");
    printf("2 2.5\n");
    for (i=3; i<=9; i++)
    {
        e=0;
        for (j=0; j<=i; j++)
        {
            e+=1.0/func(j);
        }
        printf("%d %.9lf\n", i, e);
    }
    return 0;
}