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51 lines
1.1 KiB
Python
51 lines
1.1 KiB
Python
"""
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Stalin Sort algorithm: Removes elements that are out of order.
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Elements that are not greater than or equal to the previous element are discarded.
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Reference: https://medium.com/@kaweendra/the-ultimate-sorting-algorithm-6513d6968420
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"""
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def stalin_sort(sequence: list[int]) -> list[int]:
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"""
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Sorts a list using the Stalin sort algorithm.
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>>> stalin_sort([4, 3, 5, 2, 1, 7])
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[4, 5, 7]
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>>> stalin_sort([1, 2, 3, 4])
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[1, 2, 3, 4]
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>>> stalin_sort([4, 5, 5, 2, 3])
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[4, 5, 5]
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>>> stalin_sort([6, 11, 12, 4, 1, 5])
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[6, 11, 12]
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>>> stalin_sort([5, 0, 4, 3])
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[5]
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>>> stalin_sort([5, 4, 3, 2, 1])
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[5]
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>>> stalin_sort([1, 2, 3, 4, 5])
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[1, 2, 3, 4, 5]
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>>> stalin_sort([1, 2, 8, 7, 6])
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[1, 2, 8]
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"""
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if any(x < 0 for x in sequence):
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raise ValueError("Sequence must only contain non-negative integers")
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result = [sequence[0]]
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for i in range(1, len(sequence)):
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if sequence[i] >= result[-1]:
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result.append(sequence[i])
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return result
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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