Monty Hall Problem

monty2.py

# Monty Hall Problem Simulation
# Author: Ryan Sturmer
#

import random

def play_round(doors, switch):

    # Choose the location of the car
    car = random.randint(1, doors)

    # Contestant chooses a door 
    initial_choice = random.randint(1, doors)

    # Monty opens ALL the other doors except one
    if initial_choice != car:
        monty_leaves = car # If the car wasn't chosen, Monty is forced to reveal its location
    else:
        while True:
            monty_leaves = random.randint(1, doors)
            if monty_leaves != initial_choice:
                break

    # monty_leaves is now the door that Monty DIDN'T open
    if switch:
        final_choice = monty_leaves
    else:
        final_choice = initial_choice

    victory = (final_choice == car)

    return victory, initial_choice, final_choice, car

def simulation(iterations, doors=3):
    games_won_switch = 0
    games_won_noswitch = 0
    games_won_random = 0
    for i in range(iterations):
        won_game, intial_choice, final_choice, car = play_round(doors, False)
        if(won_game):
            games_won_noswitch += 1
        won_game, intial_choice, final_choice, car = play_round(doors, True)

        if(won_game):
            games_won_switch += 1

        won_game, initial_choice, final_choice, car  = play_round(doors, random.choice([False, True]))
        if(won_game):
            games_won_random += 1

    print("")
    print("            Monty Hall Simulation")
    print("---------------------------------------------")
    print("                        Iterations: %d" % iterations)
    print("    Games won when switching doors: %d (%g%%)" % (games_won_switch, 100*float(games_won_switch)/float(iterations)))
    print("Games won when NOT switching doors: %d (%g%%)" % (games_won_noswitch, 100*float(games_won_noswitch)/float(iterations)))
    print("Games won when random switching doors: %d (%g%%)" % (games_won_random, 100*float(games_won_random)/float(iterations)))

if __name__ == '__main__':
    simulation(100000)