gcd_prob.cpp

gcd_prob.cpp

#include <iostream>
#include <random>
#include <bits/stdc++.h>

using namespace std;

int main()
{
    std::random_device m_device{};
    std::mt19937 m_generator{m_device()};
    std::uniform_int_distribution<int64_t> distribution(1, 100'000'000'000'000);
    int total = 100'000'000, num = 0;
    for (int var = 0; var < total; ++var) {
        int64_t a1 = distribution(m_generator);
        int64_t a2 = distribution(m_generator);
        if (std::__gcd(a1, a2) == 1) {
            num++;
        }
    }
    cout << 1.0 * num / total << "\t" << 6.0 / (M_PI * M_PI) << endl;

    return 0;
}
// https://stackoverflow.com/questions/30898575/inbuilt-gcda-b-function-in-c