from random import randint, choice
 
successes, attempts = 0, 0
 
while attempts < 1000:
    correct_door = randint(0, 2)
    players_door = randint(0, 2)
    unchosen_losing_doors = [ x for x in [0,1,2] if x != correct_door and x != players_door ]
    opened_door = choice(unchosen_losing_doors)
    door_to_which_we_switch = 3 - players_door - opened_door
    attempts += 1
    if correct_door == door_to_which_we_switch: successes += 1
 
print(successes)

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