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99ebd1a018
* 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 <cclauss@me.com>
29 lines
816 B
Python
29 lines
816 B
Python
def factorial(n: int) -> int:
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"""
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Calculate the factorial of a positive integer
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https://en.wikipedia.org/wiki/Factorial
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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(0.1)
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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 not isinstance(n, int):
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raise ValueError("factorial() only accepts integral values")
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if n < 0:
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raise ValueError("factorial() not defined for negative values")
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return 1 if n == 0 or n == 1 else n * factorial(n - 1)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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