counting combinations and permutations efficiently

Question

I have some code to count permutations and combinations, and I\'m trying to make it work better for large numbers.

I\'ve found a better algorithm for permutations th

Answer 1

from numpy import prod

def nCr(n,r):
    numerator = range(n, max(n-r,r),-1)
    denominator = range(1, min(n-r,r) +1,1)
    return int(prod(numerator)/prod(denominator))