#!/usr/bin/env python
"""
Created on 7 Jan 2018

@author: David Doblas Jiménez
@email: daviddoji@pm.me

Solution for problem 15 of Project Euler
https://projecteuler.net/problem=15
"""

from math import factorial

from utils import timeit


@timeit("Problem 15")
def compute():
    """
    Starting in the top left corner of a 2x2 grid, and only being able to
    move to the right and down, there are exactly 6 routes to the bottom
    right corner.

    How many such routes are there through a 20x20 grid?
    """

    n = 20
    return int(factorial(2 * n) / (factorial(n) * factorial(2 * n - n)))


if __name__ == "__main__":
    print(f"Result for Problem 15 is {compute()}")