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Optimization for shell sort (#4038)

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* fixed shell sort

* udpate code style

* Update sorts/shell_sort.py

Co-authored-by: John Law <johnlaw.po@gmail.com>

Co-authored-by: John Law <johnlaw.po@gmail.com>
This commit is contained in:
Du Yuanchao 2020-12-18 17:39:51 +08:00 committed by GitHub
parent ae8a5f8675
commit 53371b2381
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1 changed files with 9 additions and 14 deletions
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sorts/shell_sort.py
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@ -1,13 +1,5 @@
""" """
This is a pure Python implementation of the shell sort algorithm https://en.wikipedia.org/wiki/Shellsort#Pseudocode
For doctests run following command:
python -m doctest -v shell_sort.py
or
python3 -m doctest -v shell_sort.py
For manual testing run:
python shell_sort.py
""" """
@ -19,26 +11,29 @@ def shell_sort(collection):
>>> shell_sort([0, 5, 3, 2, 2]) >>> shell_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5] [0, 2, 2, 3, 5]
>>> shell_sort([]) >>> shell_sort([])
[] []
>>> shell_sort([-2, -5, -45]) >>> shell_sort([-2, -5, -45])
[-45, -5, -2] [-45, -5, -2]
""" """
# Marcin Ciura's gap sequence # Marcin Ciura's gap sequence
gaps = [701, 301, 132, 57, 23, 10, 4, 1]
gaps = [701, 301, 132, 57, 23, 10, 4, 1]
for gap in gaps: for gap in gaps:
for i in range(gap, len(collection)): for i in range(gap, len(collection)):
insert_value = collection[i]
j = i j = i
while j >= gap and collection[j] < collection[j - gap]: while j >= gap and collection[j - gap] > insert_value:
collection[j], collection[j - gap] = collection[j - gap], collection[j] collection[j] = collection[j - gap]
j -= gap j -= gap
collection[j] = insert_value
return collection return collection
if __name__ == "__main__": if __name__ == "__main__":
from doctest import testmod
testmod()
user_input = input("Enter numbers separated by a comma:\n").strip() user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")] unsorted = [int(item) for item in user_input.split(",")]
print(shell_sort(unsorted)) print(shell_sort(unsorted))