Birthday Problem

main.py

import random

days_in_year = 365
trials_size = 1000
group_sizes = range(10, 30)


def is_match_in_trial(group_size):
    bdays = [random.randint(1, days_in_year) for _ in range(group_size)]
    return len(set(bdays)) != group_size


def run_trials(group_size, number_of_trials):
    number_of_matches = len([_ for _ in range(number_of_trials) if is_match_in_trial(group_size)])
    percent = int(100.0 * number_of_matches / number_of_trials)
    print "Found matching birthdays amongst {} people in {} out of {} trials, or {}% of the time.".format(
        group_size, number_of_matches, number_of_trials, percent)


for group_size in group_sizes:
    run_trials(group_size, trials_size)
    
# Found matching birthdays amongst 10 people in 113 out of 1000 trials, or 11% of the time.
# Found matching birthdays amongst 11 people in 146 out of 1000 trials, or 14% of the time.
# Found matching birthdays amongst 12 people in 176 out of 1000 trials, or 17% of the time.
# Found matching birthdays amongst 13 people in 186 out of 1000 trials, or 18% of the time.
# Found matching birthdays amongst 14 people in 228 out of 1000 trials, or 22% of the time.
# Found matching birthdays amongst 15 people in 248 out of 1000 trials, or 24% of the time.
# Found matching birthdays amongst 16 people in 279 out of 1000 trials, or 27% of the time.
# Found matching birthdays amongst 17 people in 329 out of 1000 trials, or 32% of the time.
# Found matching birthdays amongst 18 people in 367 out of 1000 trials, or 36% of the time.
# Found matching birthdays amongst 19 people in 393 out of 1000 trials, or 39% of the time.
# Found matching birthdays amongst 20 people in 376 out of 1000 trials, or 37% of the time.
# Found matching birthdays amongst 21 people in 444 out of 1000 trials, or 44% of the time.
# Found matching birthdays amongst 22 people in 500 out of 1000 trials, or 50% of the time.
# Found matching birthdays amongst 23 people in 493 out of 1000 trials, or 49% of the time.
# Found matching birthdays amongst 24 people in 546 out of 1000 trials, or 54% of the time.
# Found matching birthdays amongst 25 people in 556 out of 1000 trials, or 55% of the time.
# Found matching birthdays amongst 26 people in 613 out of 1000 trials, or 61% of the time.
# Found matching birthdays amongst 27 people in 624 out of 1000 trials, or 62% of the time.
# Found matching birthdays amongst 28 people in 622 out of 1000 trials, or 62% of the time.
# Found matching birthdays amongst 29 people in 699 out of 1000 trials, or 69% of the time.