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98e9d6bdb6
* Fix style of the first ten solutions for Project Euler - Unify the header docstring, and add reference URLs to wikipedia or similar - Fix docstrings to be properly multilined - Add newlines where appropriate - Add doctests where they were missing - Remove doctests that test for the correct solution - fix obvious spelling or grammar mistakes in comments and exception messages - Fix line endings to be UNIX. This makes two of the files seem to have changed completely - no functional changes in any of the solutions were done (except for the spelling fixes mentioned above) * Fix docstrings and main function as per Style Guide
65 lines
1.5 KiB
Python
65 lines
1.5 KiB
Python
"""
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Project Euler Problem 3: https://projecteuler.net/problem=3
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Largest prime factor
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The prime factors of 13195 are 5, 7, 13 and 29.
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What is the largest prime factor of the number 600851475143?
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References:
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- https://en.wikipedia.org/wiki/Prime_number#Unique_factorization
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"""
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def solution(n: int = 600851475143) -> int:
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"""
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Returns the largest prime factor of a given number n.
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>>> solution(13195)
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29
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>>> solution(10)
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5
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>>> solution(17)
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17
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>>> solution(3.4)
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3
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>>> solution(0)
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Traceback (most recent call last):
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...
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ValueError: Parameter n must be greater than or equal to one.
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>>> solution(-17)
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Traceback (most recent call last):
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...
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ValueError: Parameter n must be greater than or equal to one.
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>>> solution([])
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Traceback (most recent call last):
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...
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TypeError: Parameter n must be int or castable to int.
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>>> solution("asd")
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Traceback (most recent call last):
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...
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TypeError: Parameter n must be int or castable to int.
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"""
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try:
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n = int(n)
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except (TypeError, ValueError):
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raise TypeError("Parameter n must be int or castable to int.")
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if n <= 0:
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raise ValueError("Parameter n must be greater than or equal to one.")
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prime = 1
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i = 2
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while i * i <= n:
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while n % i == 0:
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prime = i
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n //= i
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i += 1
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if n > 1:
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prime = n
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return int(prime)
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if __name__ == "__main__":
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print(f"{solution() = }")
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