From 99ebd1a01820cefb7bdf169168131289d71158fc Mon Sep 17 00:00:00 2001 From: Pooja Date: Sat, 18 Jan 2020 18:36:48 +0530 Subject: [PATCH] Create factorial_iterative.py (#1693) * Create factorial_iterative.py * Update factorial_iterative.py * Update factorial_iterative.py * Update factorial_iterative.py * print(f"factorial{n} is {factorial(n)}") * Update factorial_recursive.py Co-authored-by: Christian Clauss --- maths/factorial_iterative.py | 30 ++++++++++++++++++++++++++++++ maths/factorial_recursive.py | 24 +++++++++++------------- 2 files changed, 41 insertions(+), 13 deletions(-) create mode 100644 maths/factorial_iterative.py diff --git a/maths/factorial_iterative.py b/maths/factorial_iterative.py new file mode 100644 index 000000000..249408cb5 --- /dev/null +++ b/maths/factorial_iterative.py @@ -0,0 +1,30 @@ +# factorial of a positive integer -- https://en.wikipedia.org/wiki/Factorial + + +def factorial(n: int) -> int: + """ + >>> import math + >>> all(factorial(i) == math.factorial(i) for i in range(20)) + True + >>> factorial(0.1) + Traceback (most recent call last): + ... + ValueError: factorial() only accepts integral values + >>> factorial(-1) + Traceback (most recent call last): + ... + ValueError: factorial() not defined for negative values + """ + if n != int(n): + raise ValueError("factorial() only accepts integral values") + if n < 0: + raise ValueError("factorial() not defined for negative values") + value = 1 + for i in range(1, n + 1): + value *= i + return value + + +if __name__ == "__main__": + n = int(input("Enter a positivve integer: ").strip() or 0) + print(f"factorial{n} is {factorial(n)}") diff --git a/maths/factorial_recursive.py b/maths/factorial_recursive.py index 4f7074d16..137112738 100644 --- a/maths/factorial_recursive.py +++ b/maths/factorial_recursive.py @@ -1,26 +1,24 @@ def factorial(n: int) -> int: """ - Calculate the factorial of specified number + Calculate the factorial of a positive integer + https://en.wikipedia.org/wiki/Factorial - >>> factorial(1) - 1 - >>> factorial(6) - 720 - >>> factorial(0) - 1 - >>> factorial(-1) - Traceback (most recent call last): - ... - ValueError: factorial() not defined for negative values + >>> import math + >>> all(factorial(i) == math.factorial(i) for i in range(20)) + True >>> factorial(0.1) Traceback (most recent call last): ... ValueError: factorial() only accepts integral values + >>> factorial(-1) + Traceback (most recent call last): + ... + ValueError: factorial() not defined for negative values """ - if n < 0: - raise ValueError("factorial() not defined for negative values") if not isinstance(n, int): raise ValueError("factorial() only accepts integral values") + if n < 0: + raise ValueError("factorial() not defined for negative values") return 1 if n == 0 or n == 1 else n * factorial(n - 1)