"""This module contains a code example related to
Think Python, 2nd Edition
by Allen Downey
http://thinkpython2.com
Copyright 2015 Allen Downey
License: http://creativecommons.org/licenses/by/4.0/
"""
from __future__ import print_function, division
import random
def has_duplicates(t):
"""Returns True if any element appears more than once in a sequence.
t: list
returns: bool
"""
# make a copy of t to avoid modifying the parameter
s = t[:]
s.sort()
# check for adjacent elements that are equal
for i in range(len(s)-1):
if s[i] == s[i+1]:
return True
return False
def random_bdays(n):
"""Returns a list of integers between 1 and 365, with length n.
n: int
returns: list of int
"""
t = []
for i in range(n):
bday = random.randint(1, 365)
t.append(bday)
return t
def count_matches(num_students, num_simulations):
"""Generates a sample of birthdays and counts duplicates.
num_students: how many students in the group
num_samples: how many groups to simulate
returns: int
"""
count = 0
for i in range(num_simulations):
t = random_bdays(num_students)
if has_duplicates(t):
count += 1
return count
def main():
"""Runs the birthday simulation and prints the number of matches."""
num_students = 23
num_simulations = 1000
count = count_matches(num_students, num_simulations)
print('After %d simulations' % num_simulations)
print('with %d students' % num_students)
print('there were %d simulations with at least one match' % count)
if __name__ == '__main__':
main()