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* seperation between description and docstrings * Update maths/factorial.py --------- Co-authored-by: sarayu sree <sarayusreeyadavpadala@gmail.com> Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
69 lines
1.8 KiB
Python
69 lines
1.8 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 specified number (n!).
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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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>>> factorial(1)
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1
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>>> factorial(6)
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720
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>>> factorial(0)
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1
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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(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 in {0, 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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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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