TheAlgorithms-Python

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"""
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Project Euler Problem 8: https://projecteuler.net/problem=8
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Largest product in a series
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The four adjacent digits in the 1000-digit number that have the greatest
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product are 9 × 9 × 8 × 9 = 5832.
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    73167176531330624919225119674426574742355349194934
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    96983520312774506326239578318016984801869478851843
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    85861560789112949495459501737958331952853208805511
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    12540698747158523863050715693290963295227443043557
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    66896648950445244523161731856403098711121722383113
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    62229893423380308135336276614282806444486645238749
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    30358907296290491560440772390713810515859307960866
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    70172427121883998797908792274921901699720888093776
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    65727333001053367881220235421809751254540594752243
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    52584907711670556013604839586446706324415722155397
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    53697817977846174064955149290862569321978468622482
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    83972241375657056057490261407972968652414535100474
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    82166370484403199890008895243450658541227588666881
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    16427171479924442928230863465674813919123162824586
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    17866458359124566529476545682848912883142607690042
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    24219022671055626321111109370544217506941658960408
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    07198403850962455444362981230987879927244284909188
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    84580156166097919133875499200524063689912560717606
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    05886116467109405077541002256983155200055935729725
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    71636269561882670428252483600823257530420752963450
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Find the thirteen adjacent digits in the 1000-digit number that have the
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greatest product. What is the value of this product?
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"""
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from functools import reduce
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N = (
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    "73167176531330624919225119674426574742355349194934"
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    "96983520312774506326239578318016984801869478851843"
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    "85861560789112949495459501737958331952853208805511"
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    "12540698747158523863050715693290963295227443043557"
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    "66896648950445244523161731856403098711121722383113"
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    "62229893423380308135336276614282806444486645238749"
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    "30358907296290491560440772390713810515859307960866"
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    "70172427121883998797908792274921901699720888093776"
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    "65727333001053367881220235421809751254540594752243"
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    "52584907711670556013604839586446706324415722155397"
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    "53697817977846174064955149290862569321978468622482"
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    "83972241375657056057490261407972968652414535100474"
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    "82166370484403199890008895243450658541227588666881"
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    "16427171479924442928230863465674813919123162824586"
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    "17866458359124566529476545682848912883142607690042"
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    "24219022671055626321111109370544217506941658960408"
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    "07198403850962455444362981230987879927244284909188"
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    "84580156166097919133875499200524063689912560717606"
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    "05886116467109405077541002256983155200055935729725"
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    "71636269561882670428252483600823257530420752963450"
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)
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def solution(n: str = N) -> int:
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    """
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    Find the thirteen adjacent digits in the 1000-digit number n that have
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    the greatest product and returns it.
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    >>> solution("13978431290823798458352374")
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    609638400
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    >>> solution("13978431295823798458352374")
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    2612736000
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    >>> solution("1397843129582379841238352374")
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    209018880
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    """
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    return max(
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        # mypy cannot properly interpret reduce
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        int(reduce(lambda x, y: str(int(x) * int(y)), n[i : i + 13]))
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        for i in range(len(n) - 12)
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    )
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if __name__ == "__main__":
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    print(f"{solution() = }")
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