birthday_paradox.py

#!/usr/bin/env python3
"""
@file      birthday_paradox.py
@brief     Solves the birthday paradox.

@author    Evan Elias Young
@date      2017-07-18
@date      2022-02-04
@copyright Copyright 2022 Evan Elias Young. All rights reserved.
"""

from decimal import getcontext as setprec, Decimal
from math import factorial as fct


def get_percent(ppl: int) -> Decimal:
    """Will calculate the percent chance of matching birthdays.

    Args:
        ppl (integer): The amount of people.

    Returns:
        float: The percent chance of a match.
    """
    if ppl > 365:
        return Decimal(1 - 0)
    frac_top: Decimal = Decimal(fct(365))
    frac_bot: Decimal = Decimal((365**ppl) * fct(365 - ppl))

    return 1 - Decimal(frac_top / frac_bot)


if __name__ == "__main__":
    from random import randint

    print("Hello Console!")

    setprec().prec = 1000
    r: int = randint(1, 360)
    print(f"{r} People : {get_percent(r):0.4%}")