diff --git a/maths/combinations.py b/maths/combinations.py index a2324012c01f..f65155801b52 100644 --- a/maths/combinations.py +++ b/maths/combinations.py @@ -1,7 +1,6 @@ """ https://en.wikipedia.org/wiki/Combination """ -from math import factorial def combinations(n: int, k: int) -> int: @@ -35,7 +34,11 @@ def combinations(n: int, k: int) -> int: # to calculate a factorial of a negative number, which is not possible if n < k or k < 0: raise ValueError("Please enter positive integers for n and k where n >= k") - return factorial(n) // (factorial(k) * factorial(n - k)) + res = 1 + for i in range(k): + res = res * (n - i) + res = res // (i + 1) + return res if __name__ == "__main__":