HDU1012

u Calculate e

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 32294 Accepted Submission(s): 14471


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
using namespace std;
double fun(int n)
{
	double e = 0;
	int sum = 0;
	for (int i=0 ; i <= n; i++)
	{
		if (i == 0)
			sum = 1;
		else
			sum *= i;
		e = e + (1.0 / sum);
	}
	return e;
}
int main()
{
	cout << "n e" << endl;
	cout << "- -----------" << endl;
	double e;
	for (int i = 0; i < 10; i++)
	{
		e = fun(i);
		cout.precision(10);
		if (i>3)
			cout.setf(ios::showpoint);
		cout << i << " " << e << endl;
	}
	return 0;
}