From f1cbfd7097216f97fd76282971959c3e8501e5a6 Mon Sep 17 00:00:00 2001 From: Pradhyut21 Date: Mon, 14 Sep 2026 19:34:04 +0530 Subject: [PATCH] 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 --- sorts/shell_sort.py | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/sorts/shell_sort.py b/sorts/shell_sort.py index b65609c974b7..0a25d83f40e2 100644 --- a/sorts/shell_sort.py +++ b/sorts/shell_sort.py @@ -2,28 +2,46 @@ https://en.wikipedia.org/wiki/Shellsort#Pseudocode """ +from typing import Any, Protocol, TypeVar + + +class Comparable(Protocol): + def __lt__(self, other: Any, /) -> bool: ... + + +T = TypeVar("T", bound=Comparable) + + +def shell_sort(collection: list[T]) -> list[T]: + """Pure implementation of shell sort algorithm in Python. -def shell_sort(collection: list[int]) -> list[int]: - """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 collection[j - gap] > insert_value: + while j >= gap and insert_value < collection[j - gap]: collection[j] = collection[j - gap] j -= gap if j != i: