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51 lines
1.4 KiB
Python
51 lines
1.4 KiB
Python
"""
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This is a pure Python implementation of the merge sort algorithm
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For doctests run following command:
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python -m doctest -v merge_sort.py
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or
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python3 -m doctest -v merge_sort.py
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For manual testing run:
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python merge_sort.py
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"""
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def merge_sort(collection: list) -> list:
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"""Pure implementation of the merge 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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Examples:
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>>> merge_sort([0, 5, 3, 2, 2])
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[0, 2, 2, 3, 5]
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>>> merge_sort([])
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[]
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>>> merge_sort([-2, -5, -45])
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[-45, -5, -2]
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"""
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def merge(left: list, right: list) -> list:
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"""merge left and right
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:param left: left collection
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:param right: right collection
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:return: merge result
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"""
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def _merge():
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while left and right:
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yield (left if left[0] <= right[0] else right).pop(0)
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yield from left
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yield from right
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return list(_merge())
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if len(collection) <= 1:
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return collection
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mid = len(collection) // 2
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return merge(merge_sort(collection[:mid]), merge_sort(collection[mid:]))
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if __name__ == "__main__":
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import doctest
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doctest.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(*merge_sort(unsorted), sep=",")
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