## Python, sort, heap_sort.py

``````"""
This is a pure Python implementation of the heap sort algorithm.

For doctests run following command:
python -m doctest -v heap_sort.py
or
python3 -m doctest -v heap_sort.py

For manual testing run:
python heap_sort.py
"""

def heapify(unsorted, index, heap_size):
largest = index
left_index = 2 * index + 1
right_index = 2 * index + 2
if left_index < heap_size and unsorted[left_index] > unsorted[largest]:
largest = left_index

if right_index < heap_size and unsorted[right_index] > unsorted[largest]:
largest = right_index

if largest != index:
unsorted[largest], unsorted[index] = unsorted[index], unsorted[largest]
heapify(unsorted, largest, heap_size)

def heap_sort(unsorted):
"""
Pure implementation of the heap sort algorithm in Python
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending

Examples:
>>> heap_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]

>>> heap_sort([])
[]

>>> heap_sort([-2, -5, -45])
[-45, -5, -2]
"""
n = len(unsorted)
for i in range(n // 2 - 1, -1, -1):
heapify(unsorted, i, n)
for i in range(n - 1, 0, -1):
unsorted[0], unsorted[i] = unsorted[i], unsorted[0]
heapify(unsorted, 0, i)
return unsorted

if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(heap_sort(unsorted))
``````