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merge double_factorial (#9431)

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* merge double_factorial

* fix ruff error

* fix merge issues

* change test case

* fix import error
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dekomori_sanae09 2023-10-03 19:23:27 +05:30 committed by GitHub
parent e60779c202
commit b60a94b5b3
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3 changed files with 60 additions and 64 deletions
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60
maths/double_factorial.py Normal file
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def double_factorial_recursive(n: int) -> int:
"""
Compute double factorial using recursive method.
Recursion can be costly for large numbers.
To learn about the theory behind this algorithm:
https://en.wikipedia.org/wiki/Double_factorial
>>> from math import prod
>>> all(double_factorial_recursive(i) == prod(range(i, 0, -2)) for i in range(20))
True
>>> double_factorial_recursive(0.1)
Traceback (most recent call last):
...
ValueError: double_factorial_recursive() only accepts integral values
>>> double_factorial_recursive(-1)
Traceback (most recent call last):
...
ValueError: double_factorial_recursive() not defined for negative values
"""
if not isinstance(n, int):
raise ValueError("double_factorial_recursive() only accepts integral values")
if n < 0:
raise ValueError("double_factorial_recursive() not defined for negative values")
return 1 if n <= 1 else n * double_factorial_recursive(n - 2)
def double_factorial_iterative(num: int) -> int:
"""
Compute double factorial using iterative method.
To learn about the theory behind this algorithm:
https://en.wikipedia.org/wiki/Double_factorial
>>> from math import prod
>>> all(double_factorial_iterative(i) == prod(range(i, 0, -2)) for i in range(20))
True
>>> double_factorial_iterative(0.1)
Traceback (most recent call last):
...
ValueError: double_factorial_iterative() only accepts integral values
>>> double_factorial_iterative(-1)
Traceback (most recent call last):
...
ValueError: double_factorial_iterative() not defined for negative values
"""
if not isinstance(num, int):
raise ValueError("double_factorial_iterative() only accepts integral values")
if num < 0:
raise ValueError("double_factorial_iterative() not defined for negative values")
value = 1
for i in range(num, 0, -2):
value *= i
return value
if __name__ == "__main__":
import doctest
doctest.testmod()

33
maths/double_factorial_iterative.py
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def double_factorial(num: int) -> int:
"""
Compute double factorial using iterative method.
To learn about the theory behind this algorithm:
https://en.wikipedia.org/wiki/Double_factorial
>>> import math
>>> all(double_factorial(i) == math.prod(range(i, 0, -2)) for i in range(20))
True
>>> double_factorial(0.1)
Traceback (most recent call last):
...
ValueError: double_factorial() only accepts integral values
>>> double_factorial(-1)
Traceback (most recent call last):
...
ValueError: double_factorial() not defined for negative values
"""
if not isinstance(num, int):
raise ValueError("double_factorial() only accepts integral values")
if num < 0:
raise ValueError("double_factorial() not defined for negative values")
value = 1
for i in range(num, 0, -2):
value *= i
return value
if __name__ == "__main__":
import doctest
doctest.testmod()

31
maths/double_factorial_recursive.py
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@ -1,31 +0,0 @@
def double_factorial(n: int) -> int:
"""
Compute double factorial using recursive method.
Recursion can be costly for large numbers.
To learn about the theory behind this algorithm:
https://en.wikipedia.org/wiki/Double_factorial
>>> import math
>>> all(double_factorial(i) == math.prod(range(i, 0, -2)) for i in range(20))
True
>>> double_factorial(0.1)
Traceback (most recent call last):
...
ValueError: double_factorial() only accepts integral values
>>> double_factorial(-1)
Traceback (most recent call last):
...
ValueError: double_factorial() not defined for negative values
"""
if not isinstance(n, int):
raise ValueError("double_factorial() only accepts integral values")
if n < 0:
raise ValueError("double_factorial() not defined for negative values")
return 1 if n <= 1 else n * double_factorial(n - 2)
if __name__ == "__main__":
import doctest
doctest.testmod()