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52 lines
1.3 KiB
Python
52 lines
1.3 KiB
Python
import operator
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def strand_sort(arr: list, reverse: bool = False, solution: list | None = None) -> list:
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"""
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Strand sort implementation
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source: https://en.wikipedia.org/wiki/Strand_sort
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:param arr: Unordered input list
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:param reverse: Descent ordering flag
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:param solution: Ordered items container
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Examples:
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>>> strand_sort([4, 2, 5, 3, 0, 1])
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[0, 1, 2, 3, 4, 5]
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>>> strand_sort([4, 2, 5, 3, 0, 1], reverse=True)
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[5, 4, 3, 2, 1, 0]
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"""
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_operator = operator.lt if reverse else operator.gt
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solution = solution or []
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if not arr:
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return solution
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sublist = [arr.pop(0)]
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for i, item in enumerate(arr):
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if _operator(item, sublist[-1]):
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sublist.append(item)
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arr.pop(i)
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# merging sublist into solution list
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if not solution:
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solution.extend(sublist)
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else:
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while sublist:
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item = sublist.pop(0)
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for i, xx in enumerate(solution):
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if not _operator(item, xx):
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solution.insert(i, item)
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break
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else:
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solution.append(item)
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strand_sort(arr, reverse, solution)
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return solution
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if __name__ == "__main__":
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assert strand_sort([4, 3, 5, 1, 2]) == [1, 2, 3, 4, 5]
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assert strand_sort([4, 3, 5, 1, 2], reverse=True) == [5, 4, 3, 2, 1]
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