Solve Monty Hall problem (AKA Three Door problem)

main.cpp

#include <iostream>
#include <random>

typedef std::mt19937 EngineType;
typedef std::uniform_int_distribution<std::mt19937::result_type> GeneratorType;

bool GetIt(EngineType& engine, const GeneratorType& generator3, bool change) {
    int correct_door = generator3(engine);
    int first_choice = generator3(engine);

    if(first_choice == correct_door) {
        if(change) return false;
        else return true;
    } else {
        if(change) return true;
        else return false;
    }
}

int main() {
    EngineType eng;
    eng.seed(std::random_device()());
    GeneratorType dist3(1, 3);
    int change_sum = 0, unchange_sum = 0;
    long loop = 100000000;
    for(long i = 0; i < loop; ++i) {
        if(GetIt(eng, dist3, true))
            ++change_sum;
        if(GetIt(eng, dist3, false))
            ++unchange_sum;
    }

    std::cout << "Testing times: " << loop << std::endl;

    std::cout << "Always change choice, hit: " << change_sum
              << ", percentage: " << static_cast<double>(change_sum) / loop
              << std::endl;

    std::cout << "Always unchange choice, hit: " << unchange_sum
              << ", percentage: " << static_cast<double>(unchange_sum) / loop
              << std::endl;
}