23 lines
534 B
Markdown
23 lines
534 B
Markdown
---
|
|
title: factorial
|
|
tags: math,recursion,beginner
|
|
---
|
|
|
|
Calculates the factorial of a number.
|
|
|
|
- Use recursion.
|
|
- If `num` is less than or equal to `1`, return `1`.
|
|
- Otherwise, return the product of `num` and the factorial of `num - 1`.
|
|
- Throws an exception if `num` is a negative or a floating point number.
|
|
|
|
```py
|
|
def factorial(num):
|
|
if not ((num >= 0) and (num % 1 == 0)):
|
|
raise Exception("Number can't be floating point or negative.")
|
|
return 1 if num == 0 else num * factorial(num - 1)
|
|
```
|
|
|
|
```py
|
|
factorial(6) # 720
|
|
```
|