From d961217d5ff106244ca424495d927412d7c96080 Mon Sep 17 00:00:00 2001
From: Fayupable <90789180+Fayupable@users.noreply.github.com>
Date: Thu, 24 Sep 2026 17:08:14 +0300
Subject: [PATCH] sorts: type patience_sort's Stack for any comparable item
 (#15427)

Part of #15234.
---
 sorts/patience_sort.py | 26 ++++++++++++++++++++++----
 tests/test_sorts.py    |  1 +
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/sorts/patience_sort.py b/sorts/patience_sort.py
index 63c2c8ffe..56ee1b06d 100644
--- a/sorts/patience_sort.py
+++ b/sorts/patience_sort.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 from bisect import bisect_left
 from functools import total_ordering
 from heapq import merge
+from typing import Protocol
 
 """
 A pure Python implementation of the patience sort algorithm
@@ -19,16 +20,22 @@ python3 patience_sort.py
 """
 
 
+class Comparable(Protocol):
+    def __lt__(self, other: object, /) -> bool: ...
+
+
 @total_ordering
-class Stack(list):
-    def __lt__(self, other):
+class Stack[T: Comparable](list[T]):
+    def __lt__(self, other: Stack[T]) -> bool:
         return self[-1] < other[-1]
 
-    def __eq__(self, other):
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, Stack):
+            return NotImplemented
         return self[-1] == other[-1]
 
 
-def patience_sort(collection: list) -> list:
+def patience_sort[T: Comparable](collection: list[T]) -> list[T]:
     """A pure implementation of patience sort algorithm in Python
 
     :param collection: some mutable ordered collection with heterogeneous
@@ -44,6 +51,17 @@ def patience_sort(collection: list) -> list:
 
     >>> patience_sort([-3, -17, -48])
     [-48, -17, -3]
+
+    >>> patience_sort(['d', 'a', 'b', 'e']) == sorted(['d', 'a', 'b', 'e'])
+    True
+
+    >>> patience_sort([3.3, 1.1, 2.2])
+    [1.1, 2.2, 3.3]
+
+    >>> patience_sort([1, "a"])  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+        ...
+    TypeError: '<' not supported between instances of 'str' and 'int'
     """
     stacks: list[Stack] = []
     # sort into stacks
diff --git a/tests/test_sorts.py b/tests/test_sorts.py
index e0b77ac79..a4a8ed741 100644
--- a/tests/test_sorts.py
+++ b/tests/test_sorts.py
@@ -158,6 +158,7 @@ def test_rec_insertion_sort(case) -> None:
         odd_even_sort,
         odd_even_transposition,
         pancake_sort,
+        patience_sort,
         reversort,
         selection_sort,
         shrink_shell_sort,