Simulation to the Monty Hall Paradox

monty_hall.cpp

/*
    Simulation to the Monty Hall Paradox
    https://es.wikipedia.org/wiki/Problema_de_Monty_Hall
*/

#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;


int main() 
{
    srand (time(NULL));
    unsigned int num_of_games = 100000;
    unsigned int common_winners = 0;
    unsigned int smart_winners = 0;

    // monty hall - 100000 simulations
    for (unsigned int i=0; i<num_of_games; i++ ) 
    {
    int door_prize = 1+rand()%3;
    int common_decision =  1+rand()%3;
    int revealed_door;
    int smart_decision;
    do
    {
        revealed_door = 1+rand()%3;
    }while(revealed_door == door_prize || revealed_door == common_decision);
                                                    /*
                                                    the second decision must be different from
                                                    the first door chosen and also different from
                                                    the revealed door.
                                                    */ 
    do
    {
        smart_decision = 1+rand()%3;
    } while (common_decision == smart_decision || revealed_door == smart_decision); 
                                                    /*
                                                    the second decision must be different from the
                                                    first door chosen and also different from the
                                                    door revealed.
                                                    */  


    unsigned int random_participant_type = rand() % 2 + 1;
    switch (random_participant_type)
        {
        case 1: // common participant
            if (common_decision == door_prize) common_winners++;
            break;
        
        case 2: // smart participant
            if (smart_decision == door_prize) smart_winners++;
            break;
        }
    
    } // end simulations, results:
    
    cout<<endl<<".:SMARTS:."<<endl;
    cout<< "winners: "<<smart_winners<<endl;
    cout<< "percentage of success: "<<smart_winners*100/num_of_games<<" %"<<endl;
    cout<<endl;
    cout<<endl<<".:COMMONS:."<<endl;
    cout<< "winners: "<<common_winners<<endl;
    cout<< "percentage of success: "<<common_winners*100/num_of_games<<" %"<<endl;
    cout<<endl;

    system("pause");
    
}