How to write Combination and Permutation from 2 numbers n and k in Ruby/Python?

Question

For example, if I have 100 distinguishable dogs and I want to randomly pick 3 of them. With a pocket-size calculator, I would do 100C3 or something similar. How can I do this in Ruby and Python?

Edition 1: My questions were solved from Razvans and Riccardo Bucco solutions. (I flipped a fair coin once to decide to whom I give a check mark and to whom I give an upvote).

Thank you, everyone.

Answer 1

You would do this in python:

from math import comb

n_combinations = comb(100, 3)

Similarly, for permutations:

from math import perm

n_permutations = perm(100, 3)

perm and comb can be used only with python > 3.8. For older versions of python please use these functions:

from math import factorial

def comb(n, k):
    return factorial(n) // factorial(k) // factorial(n - k)

def perm(n, k=None):
    return factorial(n) // factorial(n - (k or n))