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

You could input two integers and import math library to find the factorial and then apply the nCr formula

import math
n,r=[int(_)for _ in raw_input().split()]
f=math.factorial
print f(n)/f(r)/f(n-r)