TheAlgorithms-Python

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"""
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https://en.wikipedia.org/wiki/Shellsort#Pseudocode
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"""
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def shell_sort(collection: list[int]) -> list[int]:
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    """Pure implementation of shell sort algorithm in Python
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    :param collection:  Some mutable ordered collection with heterogeneous
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    comparable items inside
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    :return:  the same collection ordered by ascending
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    >>> shell_sort([0, 5, 3, 2, 2])
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    [0, 2, 2, 3, 5]
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    >>> shell_sort([])
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    []
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    >>> shell_sort([-2, -5, -45])
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    [-45, -5, -2]
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    """
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    # Marcin Ciura's gap sequence
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    gaps = [701, 301, 132, 57, 23, 10, 4, 1]
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    for gap in gaps:
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        for i in range(gap, len(collection)):
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            insert_value = collection[i]
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            j = i
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            while j >= gap and collection[j - gap] > insert_value:
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                collection[j] = collection[j - gap]
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                j -= gap
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            if j != i:
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                collection[j] = insert_value
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    return collection
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if __name__ == "__main__":
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    from doctest import testmod
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    testmod()
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    user_input = input("Enter numbers separated by a comma:\n").strip()
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    unsorted = [int(item) for item in user_input.split(",")]
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    print(shell_sort(unsorted))
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