8.1.5(1-4)

#include <iostream>
#include <string>
using namespace std;

long EuclidRecursive(long a, long b) {

    if (a == b) {
        return a;
    }
    if (a > b) {
        long tmp = a;
        a = b;
        b = tmp;
    }
    return EuclidRecursive(a, b - a);
}

long EuclidIterated(long a, long b) {
    long tmp;
    while (a != b) {
        if (a > b) {
            tmp = a;
            a = b;
            b = tmp;
        }
        b = b - a;
    }
    return a;
}

void reduceFraction(long& a, long& b, long nod = 0) {
    if (!nod)
        nod = EuclidIterated(a, b);

    a = a / nod;
    b = b / nod;
}

long nok(long a, long b, long nod = 0) {
    if (!nod)
        nod = EuclidIterated(a, b);

    return a / nod * b;
}

void solveFractionPlus(long& a, long& b, long c, long d) {
    long nodBC = EuclidIterated(b, c);
    long nokBC = nok(b, c, nodBC);

    long mult1 = nokBC / b, mult2 = nokBC / c;

    a = a * mult1 + d * mult2;
    b = nokBC;

    reduceFraction(a, b);
}


int main() {
    cout << endl << " a     d ";
    cout << endl << "--- + ---";
    cout << endl << " b     c ";
    cout << endl << "Enter values a, b, c, d: ";
    long a, b, c, d;
    cin >> a >> b >> c >> d;

    solveFractionPlus(a, b, c, d);

    cout << " " << a << endl;
    cout << "-----" << endl;
    cout << " " << b;

}