Python/sorts/pigeon_sort.py
Christian Clauss 1f8a21d727
Tighten up psf/black and flake8 (#2024)
* Tighten up psf/black and flake8

* Fix some tests

* Fix some E741

* Fix some E741

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-05-22 08:10:11 +02:00

69 lines
1.7 KiB
Python

"""
This is an implementation of Pigeon Hole Sort.
For doctests run following command:
python3 -m doctest -v pigeon_sort.py
or
python -m doctest -v pigeon_sort.py
For manual testing run:
python pigeon_sort.py
"""
def pigeon_sort(array):
"""
Implementation of pigeon hole sort algorithm
:param array: Collection of comparable items
:return: Collection sorted in ascending order
>>> pigeon_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> pigeon_sort([])
[]
>>> pigeon_sort([-2, -5, -45])
[-45, -5, -2]
"""
if len(array) == 0:
return array
# Manually finds the minimum and maximum of the array.
min = array[0]
max = array[0]
for i in range(len(array)):
if array[i] < min:
min = array[i]
elif array[i] > max:
max = array[i]
# Compute the variables
holes_range = max - min + 1
holes = [0 for _ in range(holes_range)]
holes_repeat = [0 for _ in range(holes_range)]
# Make the sorting.
for i in range(len(array)):
index = array[i] - min
if holes[index] != array[i]:
holes[index] = array[i]
holes_repeat[index] += 1
else:
holes_repeat[index] += 1
# Makes the array back by replacing the numbers.
index = 0
for i in range(holes_range):
while holes_repeat[i] > 0:
array[index] = holes[i]
index += 1
holes_repeat[i] -= 1
# Returns the sorted array.
return array
if __name__ == "__main__":
user_input = input("Enter numbers separated by comma:\n")
unsorted = [int(x) for x in user_input.split(",")]
print(pigeon_sort(unsorted))