（HDOJ 1012）u Calculate e

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

 

Recommend

JGShining

 

 AC code:

#include <stdio.h>
#include<math.h>

long int f(int n)
{
    if(n==0||n==1)
     return 1;
    else
     return n*f(n-1);
}

double sum(int n)
{
    int i;
    double s=0.000000000;
    for(i=0; i<=n;i++)
    {
        s+=(double)1/f(i);
    }
    return s;
}

int main()
{
    int i;
   printf("n e\n");
   printf("- -----------\n");
   for(i=0;i<=9;i++)
   {
     if(i==0)
     {
         printf("%d %d\n",i,1);
        }
     
     else if(i==1)
     {
         printf("%d %d\n",i,2);
        }
        else if(i==2)
     {
         printf("%d %.1f\n",i,2.5);
        }
        else 
        {
     printf("%d %.9lf\n",i,sum(i));
     }
    }

    return 0;

}