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7f04e5cd34
* spelling corrections * review * improved documentation, removed redundant variables, added testing * added type hint * camel case to snake case * spelling fix * review * python --> Python # it is a brand name, not a snake * explicit cast to int * spaces in int list * "!= None" to "is not None" * Update comb_sort.py * various spelling corrections in documentation & several variables naming conventions fix * + char in file name * import dependency - bug fix Co-authored-by: John Law <johnlaw.po@gmail.com>
31 lines
875 B
Python
31 lines
875 B
Python
# factorial of a positive integer -- https://en.wikipedia.org/wiki/Factorial
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def factorial(n: int) -> int:
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"""
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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 n != int(n):
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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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value = 1
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for i in range(1, n + 1):
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value *= i
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return value
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if __name__ == "__main__":
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n = int(input("Enter a positive integer: ").strip() or 0)
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print(f"factorial{n} is {factorial(n)}")
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