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sayan sompre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>Christian Clausscclauss* Add recursive factorial implementation * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * updating DIRECTORY.md * Fix docstring and update input for factorial functions Corrected docstring and improved input handling. --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: cclauss <cclauss@users.noreply.github.com>
73 lines
2.0 KiB
Python
73 lines
2.0 KiB
Python
"""
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Factorial of a positive integer -- https://en.wikipedia.org/wiki/Factorial
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"""
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def factorial(number: int) -> int:
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"""
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Calculate the factorial of the specified number.
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>>> import math
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>>> all(factorial(i) == math.factorial(i) for i in range(20))
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True
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>>> factorial(0)
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1
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>>> factorial(1)
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1
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>>> factorial(5)
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120
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>>> factorial(0.1)
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Traceback (most recent call last):
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...
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ValueError: factorial() only accepts integral values
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>>> factorial(-1)
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Traceback (most recent call last):
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...
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ValueError: factorial() not defined for negative values
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"""
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if number != int(number):
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raise ValueError("factorial() only accepts integral values")
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if number < 0:
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raise ValueError("factorial() not defined for negative values")
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value = 1
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for i in range(1, number + 1):
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value *= i
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return value
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def factorial_recursive(number: int) -> int:
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"""
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Calculate the factorial of a number using recursion.
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>>> import math
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>>> all(factorial_recursive(i) == math.factorial(i) for i in range(20))
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True
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>>> factorial_recursive(0)
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1
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>>> factorial_recursive(1)
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1
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>>> factorial_recursive(5)
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120
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>>> factorial_recursive(0.1)
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Traceback (most recent call last):
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...
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ValueError: factorial_recursive() only accepts integral values
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>>> factorial_recursive(-1)
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Traceback (most recent call last):
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...
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ValueError: factorial_recursive() not defined for negative values
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"""
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if not isinstance(number, int):
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raise ValueError("factorial_recursive() only accepts integral values")
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if number < 0:
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raise ValueError("factorial_recursive() not defined for negative values")
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return 1 if number in {0, 1} else number * factorial_recursive(number - 1)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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n = int(input("Enter a positive integer: ").strip() or 0)
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print(f"{n = } {factorial(n) = } {factorial_recursive(n) = }")
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