Files
Python/sorts/shell_sort.py
K M PRADHYUT 92fa11bd39 sorts: make shell_sort work with any Comparable, not just int (#15326)
* sorts: make shell_sort work with any Comparable, not just int

Use a Comparable Protocol + TypeVar bound so that shell_sort
correctly expresses it can sort any orderable type, not just
integers. Adds string and float doctest examples.

Part of #15234

* fix: use PEP 695 type params, remove TypeVar import
2026-09-18 02:41:47 +02:00

56 lines
1.5 KiB
Python

"""
https://en.wikipedia.org/wiki/Shellsort#Pseudocode
"""
from typing import Any, Protocol
class Comparable(Protocol):
def __lt__(self, other: Any, /) -> bool: ...
def shell_sort[T: Comparable](collection: list[T]) -> list[T]:
"""Pure implementation of shell sort algorithm in Python.
:param collection: Some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> shell_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> shell_sort([])
[]
>>> shell_sort([-2, -5, -45])
[-45, -5, -2]
>>> shell_sort(["c", "a", "b"])
['a', 'b', 'c']
>>> shell_sort([2.5, -1.0, 0.0])
[-1.0, 0.0, 2.5]
>>> shell_sort([0, 5, 3, 2, 2]) == sorted([0, 5, 3, 2, 2])
True
>>> shell_sort(["c", "a", "b"]) == sorted(["c", "a", "b"])
True
"""
# Marcin Ciura's gap sequence
gaps = [701, 301, 132, 57, 23, 10, 4, 1]
for gap in gaps:
for i in range(gap, len(collection)):
insert_value = collection[i]
j = i
while j >= gap and insert_value < collection[j - gap]:
collection[j] = collection[j - gap]
j -= gap
if j != i:
collection[j] = insert_value
return collection
if __name__ == "__main__":
from doctest import testmod
testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(shell_sort(unsorted))