tuesday-child-puzzle.py

# The Tuesday Child Puzzle!

# I have two children.
# One of them is a girl born on a Tuesday.
# What is the probability that I have two girls?

from enum import Enum
from random import randint

class Child():
    def __init__(self, sex, day):
        self.sex = sex
        self.day = day

class Days(Enum):
    MONDAY = 0
    TUESDAY = 1
    WEDNESDAY = 2
    THURSDAY = 3
    FRIDAY = 4
    SATURDAY = 5
    SUNDAY = 6

class Sex(Enum):
    BOY = 0
    GIRL = 1

def birth_child():
    birth_sex = Sex(randint(Sex.BOY.value, Sex.GIRL.value))
    birth_day = Days(randint(Days.MONDAY.value, Days.SUNDAY.value))
    print("Birthing a " + str(birth_sex) + " on a " + str(birth_day))
    return Child(birth_sex, birth_day)

def has_tuesday_girl(trial):
    for child in trial:
        if child.sex is Sex.GIRL and child.day is Days.TUESDAY:
            return True
    return False
    
def both_are_girls(trial):
    return trial[0].sex is Sex.GIRL and trial[1].sex is Sex.GIRL

def do_trial():
    return birth_child(), birth_child()
        
def main():
    max_trials = 100000
    total_trials = 0
    
    trials = [do_trial() for trial in range(0, max_trials)]
    has_tuesday_girls = [trial for trial in trials if has_tuesday_girl(trial)]
    result = [trial for trial in has_tuesday_girls if both_are_girls(trial)]
    
    per_born_on_tuesday = round(100 * len(has_tuesday_girls) / max_trials, 2)
    per_result = round(100 * len(result) / len(has_tuesday_girls), 2)
    per_error = round(100 * (abs(per_result - (100 * (13/27))) / (100 * (13/27))), 2)
    print("\nOut of " + str(max_trials) + " trials:")
    print(str(len(has_tuesday_girls)) + " have girls born on a Tuesday (" + str(per_born_on_tuesday) + "%)")
    print(str(len(result)) + " of those have two girls (" + str(per_result) + "%)")
    print("Expected probability: 13/27 (" + str(per_error) + "% error)")
main()