From 6435da530ec38d61684b930a3a8264a10821f8c5 Mon Sep 17 00:00:00 2001
From: Gavin-Yau <2695188238@qq.com>
Date: Fri, 11 Sep 2026 18:15:47 +0800
Subject: [PATCH] sorts: type cocktail shaker sort for comparable items

---
 sorts/cocktail_shaker_sort.py | 12 +++++++++++-
 tests/test_sorts.py           |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/sorts/cocktail_shaker_sort.py b/sorts/cocktail_shaker_sort.py
index de126426d986..e802336e4321 100644
--- a/sorts/cocktail_shaker_sort.py
+++ b/sorts/cocktail_shaker_sort.py
@@ -4,8 +4,14 @@
 https://en.wikipedia.org/wiki/Cocktail_shaker_sort
 """
 
+from typing import Protocol
 
-def cocktail_shaker_sort(arr: list[int]) -> list[int]:
+
+class Comparable(Protocol):
+    def __lt__(self, other: object, /) -> bool: ...
+
+
+def cocktail_shaker_sort[T: Comparable](arr: list[T]) -> list[T]:
     """
     Sorts a list using the Cocktail Shaker Sort algorithm.
 
@@ -28,6 +34,10 @@ def cocktail_shaker_sort(arr: list[int]) -> list[int]:
     Traceback (most recent call last):
         ...
     TypeError: 'tuple' object does not support item assignment
+    >>> cocktail_shaker_sort([1, "a"])  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+        ...
+    TypeError: ...
     """
     start, end = 0, len(arr) - 1
 
diff --git a/tests/test_sorts.py b/tests/test_sorts.py
index 9bcec1f6b335..799ab5979dff 100644
--- a/tests/test_sorts.py
+++ b/tests/test_sorts.py
@@ -115,6 +115,7 @@ def test_sort_matches_builtin(sort, case):
         bubble_sort_iterative,
         bubble_sort_recursive,
         circle_sort,
+        cocktail_shaker_sort,
         gnome_sort,
         insertion_sort,
         merge_sort,