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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
40 lines
1002 B
Python
40 lines
1002 B
Python
"""
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Project Euler Problem 4: https://projecteuler.net/problem=4
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Largest palindrome product
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A palindromic number reads the same both ways. The largest palindrome made
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from the product of two 2-digit numbers is 9009 = 91 × 99.
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Find the largest palindrome made from the product of two 3-digit numbers.
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References:
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- https://en.wikipedia.org/wiki/Palindromic_number
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"""
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def solution(n: int = 998001) -> int:
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"""
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Returns the largest palindrome made from the product of two 3-digit
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numbers which is less than n.
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>>> solution(20000)
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19591
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>>> solution(30000)
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29992
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>>> solution(40000)
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39893
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"""
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answer = 0
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for i in range(999, 99, -1): # 3 digit numbers range from 999 down to 100
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for j in range(999, 99, -1):
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product_string = str(i * j)
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if product_string == product_string[::-1] and i * j < n:
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answer = max(answer, i * j)
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return answer
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if __name__ == "__main__":
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print(f"{solution() = }")
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