mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-25 04:30:15 +00:00
33 lines
914 B
Python
33 lines
914 B
Python
def polygonal_num(num: int, sides: int) -> int:
|
|
"""
|
|
Returns the `num`th `sides`-gonal number. It is assumed that `num` >= 0 and
|
|
`sides` >= 3 (see for reference https://en.wikipedia.org/wiki/Polygonal_number).
|
|
|
|
>>> polygonal_num(0, 3)
|
|
0
|
|
>>> polygonal_num(3, 3)
|
|
6
|
|
>>> polygonal_num(5, 4)
|
|
25
|
|
>>> polygonal_num(2, 5)
|
|
5
|
|
>>> polygonal_num(-1, 0)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: Invalid input: num must be >= 0 and sides must be >= 3.
|
|
>>> polygonal_num(0, 2)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: Invalid input: num must be >= 0 and sides must be >= 3.
|
|
"""
|
|
if num < 0 or sides < 3:
|
|
raise ValueError("Invalid input: num must be >= 0 and sides must be >= 3.")
|
|
|
|
return ((sides - 2) * num**2 - (sides - 4) * num) // 2
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|