Dev - C++ - Ayuda con ejercicios del numero de Euler en C++

#include <iostream>

#include <iomanip>

int main()

{

    const double nE = 2.71828182845904525356;

    double e1 = 1.0, e2 = 1.0;

    double margen = 0.00000000001;

    double diferencia1 = nE - e1;

    double diferencia2 = nE - e2;

    double factorial = 1.0;

    int k = 1;

    int n = 1;

    while (margen < diferencia1 || margen < diferencia2)

    {

        e2 = e1;

        for (int j = n; j <= k; j++)

            factorial = factorial * j;

        k++;

        n++;

        e1 += (1 / factorial);

        diferencia1 = nE - e1;

        diferencia2 = nE - e2;

    }

    std::cout << std::setprecision(20) << std::fixed;

    std::cout << "\nValor de e = " << e1 << std::endl;

    return 0;

}

#include <iostream>

#include <iomanip>

#include <cmath>

long long int factorial(int n);

int main()

{

        int k = 3, i = 1;

        float x = 30.0f;

        long double seno;

        const double PI = 3.14159265359;

        x = 30 * PI / 180.0f;

        seno = x;

        do {

            if (i % 2 == 0)

                seno = seno + pow(x, k) / factorial(k);

            else

                seno = seno - pow(x, k) / factorial(k);

            k += 2; i++;

        } while (abs(pow(x, k) / factorial(k + 1)) > pow(10, -6));

        std::cout << std::setprecision(20) << std::fixed;

        std::cout << "\nSeno: " << seno << std::endl;

        return 0;

}

long long int factorial(int n)

{

    long long int fact = 1;

    for (int i = 1; i <= n; i++)

        fact = fact * i;

    return fact;

}