Число e

#include <iostream>
using namespace std;

double factorial(int n){
  double res = 1;
    int i = 1;
    while (i <= n){
        res *= i;
        i++;
    }
    return 1.0/res;
}


void fill(double a[],int n){
    double sum=0;
    for (int i = 0; i < n+1; i++) {

        a[i] = factorial(i);
         sum=sum+a[i];
    }
cout<<sum<<endl;
}



int main()


{
    int n;
    cout << "Введите количество элементов  : ";
    cin >> n;
    double * a = new double[n+1];

    fill(a, n);
    delete [] a;

  }