O#1

#include "stdafx.h"
#include <iostream>
#include "math.h"

using namespace std;

int fact(int n) {
    switch (n) {
    case 0: return 1;
    case 1: return 1;
    default: {
        int k = 1;
        for (int i = 1; i <= n; i++)
            k *= i;
        return k;
    }
    }
}

void main()
{
    double e;
    cout << "Input accuracy of calculation" << endl;
    cin >> e;
    double x;
    cout << "Input point of equation" << endl;
    cin >> x;
    double r, t = INT32_MAX;
    int i = 1;
    while (t > e) {
        t = pow(-1, i + 1) * pow(x, 2 * i - 1) * (2 * i + 1 + x) / (fact(2 * i + 1) * 1.0);
        r += t;
        i++;
    }
    cout.precision(15);
    cout << "r = " << r << endl;
    system("pause");
}