monty.py

import sys
import random
results = []

strategy = 'stay'
if len(sys.argv) > 1:
    strategy = sys.argv[1]

for i in range(0, 100):
    # Shuffle doors
    doors = ['car', 'goat', 'goat']
    random.shuffle(doors)
    print('Doors: {}'.format(', '.join(doors)))

    # Monty knows the goats
    goats = [i for i, door in enumerate(doors) if door == 'goat']

    # Player chooses
    choice = random.randrange(0, 3)
    print('Player chooses door {}'.format(choice + 1))

    # Monty reveals one of the goats
    revealed = random.choice(list(set(goats) - set([choice])))
    print('Monty reveals goat behind door {}'.format(revealed + 1))

    if strategy == 'switch':
        choice = list(set([0, 1, 2]) - set([revealed]) - set([choice]))[0]

    print('Player chooses door {}, a {}.'.format((choice + 1), doors[choice]))

    results.append(doors[choice])
    print()


num_cars = len([r for r in results if r == 'car'])
print('Success rate: {}%'.format(int(num_cars / len(results) * 100)))