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66 lines
1.7 KiB
Python
66 lines
1.7 KiB
Python
'''
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This is a pure python implementation of the heap sort algorithm.
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For doctests run following command:
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python -m doctest -v heap_sort.py
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or
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python3 -m doctest -v heap_sort.py
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For manual testing run:
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python heap_sort.py
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'''
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from __future__ import print_function
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def heapify(unsorted, index, heap_size):
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largest = index
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left_index = 2 * index + 1
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right_index = 2 * index + 2
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if left_index < heap_size and unsorted[left_index] > unsorted[largest]:
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largest = left_index
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if right_index < heap_size and unsorted[right_index] > unsorted[largest]:
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largest = right_index
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if largest != index:
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unsorted[largest], unsorted[index] = unsorted[index], unsorted[largest]
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heapify(unsorted, largest, heap_size)
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def heap_sort(unsorted):
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'''
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Pure implementation of the heap 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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>>> heap_sort([0, 5, 3, 2, 2])
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[0, 2, 2, 3, 5]
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>>> heap_sort([])
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[]
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>>> heap_sort([-2, -5, -45])
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[-45, -5, -2]
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'''
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n = len(unsorted)
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for i in range(n // 2 - 1, -1, -1):
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heapify(unsorted, i, n)
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for i in range(n - 1, 0, -1):
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unsorted[0], unsorted[i] = unsorted[i], unsorted[0]
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heapify(unsorted, 0, i)
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return unsorted
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if __name__ == '__main__':
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import sys
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if sys.version_info.major < 3:
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input_function = raw_input
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else:
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input_function = input
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user_input = input_function('Enter numbers separated by a comma:\n')
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unsorted = [int(item) for item in user_input.split(',')]
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print(heap_sort(unsorted))
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