monty_hall_chinese_edition.py

#!/usr/bin/env python3

import random

DOORS = 4
EPOCH = 10000
KEY_POINT_TIME = 2

# ENUM
result = {
        'win': 0,
        'lose': 1,
        'none': 2
        }

# global variable
game_history = []


def main():
    customize()
    for _ in range(EPOCH):
        run_the_test()
    cal_probability()


def do_guess(car, now_doors) -> (int, int, int):
    """Participant makes decision here"""

    choose_this_time = random.choice(now_doors)
    # remove the "car door" and the "door choose this time"
    now_doors.remove(car)
    if car != choose_this_time:
        now_doors.remove(choose_this_time)
    
    if len(now_doors) == 0: # choose_this_time != car
        return None, choose_this_time, result['lose']
    elif len(now_doors) == 1 and choose_this_time == car: # choose_this_time == car
        return None, choose_this_time, result['win']
    else:
        now_open = random.choice(now_doors)

    return now_open, choose_this_time, result['none']


def judge(r, choose_history) -> None:
#    if r:
#        print("lose")
#    else:
#        print("win")
    game_history.append({'choose': choose_history, 'result': r})


def run_the_test() -> None:
    """Run the test for 1 time"""

    # initialize the doors
    now_doors = [i for i in range(DOORS)]
    # choose which door has car
    car = random.choice(now_doors)
    # initialize the guess history
    choose_history = []

    while len(now_doors) > 1:
        now_open, choose_this_time, r = do_guess(car, now_doors.copy())
        choose_history.append(choose_this_time)

        if r == result['none']: # not win, not lose, the game continues
            now_doors.remove(now_open)
        else:
            judge(r, choose_history)
            return


def cal_probability() -> None:
    """calculate the probability"""

    change_win = 0
    change_lose = 0
    unchange_win = 0
    unchange_lose = 0
    for game in game_history:
        # change
        if game['choose'][KEY_POINT_TIME] != game['choose'][KEY_POINT_TIME - 1]:
            if game['result'] == result['win']:
                change_win += 1
            else:
                change_lose += 1
        # unchange
        else:
            if game['result'] == result['win']:
                unchange_win += 1
            else:
                unchange_lose += 1
            
    print(f"第 {str(KEY_POINT_TIME)} 次時換：")
    if change_win + change_lose == 0: # prevent ZeroDivisionError
        change_win_ratio = 100
    else:
        change_win_ratio = round(change_win / (change_win+change_lose), 2) * 100
    print(f"   贏：{change_win_ratio}%")
    print(f"   輸：{100 - change_win_ratio}%")

    print(f"第 {str(KEY_POINT_TIME)} 次時不換：")
    if unchange_win + unchange_lose == 0: # prevent ZeroDivisionError
        unchange_win_ratio = 100
    else:
        unchange_win_ratio = round(unchange_win / (unchange_win+unchange_lose), 2) * 100
    print(f"   贏：{unchange_win_ratio}%")
    print(f"   輸：{100 - unchange_win_ratio}%")


def validate() -> None:
    if KEY_POINT_TIME > (DOORS - 2):
        print(f"**錯誤：{DOORS} 扇門時最多 {DOORS - 2} 次**")
        exit()
        

def customize() -> None:
    """Customize input parameter"""

    global DOORS, EPOCH, KEY_POINT_TIME
    try:
        # Doors
        q_doors = input(f"要有幾扇門？[預設 {DOORS}] ")
        if q_doors != '' and int(q_doors) > 2:
            DOORS = int(q_doors)
        # Epoch
        q_epoch = input(f"測試幾次？[預設 {EPOCH}] ")
        if q_epoch != '' and int(q_epoch) > 0:
            EPOCH = int(q_epoch)
        # Key point time
        q_key = input(f"第幾次問要不要換？[預設 {KEY_POINT_TIME}] ")
        if q_key != '' and int(q_key) > 0:
            KEY_POINT_TIME = int(q_key)

        print("\n--------\n")
        validate()
        print(f"{DOORS} 扇門、測試 {EPOCH} 次、第 {KEY_POINT_TIME} 問要不要換\n")
    except ValueError:
        print("**錯誤：請輸入數字**")
        exit()


main()