monty.py

"""
A simple simulation of the Monty Hall problem
"""

import random


ROUNDS = 100_000
WINS = 0

for round in range(ROUNDS):
    # place the car uniformly at random
    car_door = random.randint(1, 3)
    # contestant picks a door uniformly at random
    pick = random.randint(1, 3)

    # host opens a door not picked by the user that contains a goat
    for i in [1,2,3]:
        if i == car_door or i == pick:
            continue
        open_door = i
        break

    # The user switches to the other non-opened door
    for i in [1,2,3]:
        if i == pick or i == open_door:
            continue
        pick = i
        break

    if pick == car_door:
        WINS += 1

print(f"played {ROUNDS} rounds won {WINS} ({100.0*WINS / ROUNDS}%)")