HDU 1008 u Calculate e

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

 

Source

Greater New York 2000

 

 

简单题

#include<stdio.h>
int fact(int n)
{
    int res=1;
    while(n>=1)
    {
        res*=n;
        n--;
    }
    return res;
}
int main()
{
    printf("n e
- -----------
0 1
1 2
2 2.5
3 2.666666667
4 2.708333333
");
    int n,i;
    double e;
    for(n=5;n<=9;n++)
    {
        e=0.0;
        for(i=0;i<=n;i++)
        {
            e+=1.0/double(fact(i));
        }
        printf("%d %.9lf
",n,e);
    }
    return 0;
}