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* Update factorial.py
* updating DIRECTORY.md
* Update dynamic_programming/factorial.py
* Update factorial.py
Co-authored-by: mateuszz0000 <mtszzwdzk@gmail.com>
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
28 lines
585 B
Python
28 lines
585 B
Python
# Factorial of a number using memoization
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from functools import lru_cache
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@lru_cache
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def factorial(num: int) -> int:
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"""
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>>> factorial(7)
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5040
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>>> factorial(-1)
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Traceback (most recent call last):
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...
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ValueError: Number should not be negative.
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>>> [factorial(i) for i in range(10)]
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[1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880]
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"""
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if num < 0:
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raise ValueError("Number should not be negative.")
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return 1 if num in (0, 1) else num * factorial(num - 1)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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