sorts: make recursive bubble sort support comparable items (#15339)

sorts/bubble_sort_recursive.py

@@ -1,6 +1,17 @@
-def bubble_sort_recursive(arr: list[int]) -> list[int]:
+"""
+A pure Python implementation of the recursive bubble sort algorithm.
+"""
+
+from typing import Protocol
+
+
+class Comparable(Protocol):
+    def __lt__(self, other: object, /) -> bool: ...
+
+
+def bubble_sort_recursive[T: Comparable](arr: list[T]) -> list[T]:
     """
-    Sorts a list of integers using the recursive Bubble Sort algorithm.
+    Sorts a list of comparable items using the recursive Bubble Sort algorithm.
 
     >>> bubble_sort_recursive([5, 1, 4, 2, 8])
     [1, 2, 4, 5, 8]
@@ -12,6 +23,14 @@ def bubble_sort_recursive(arr: list[int]) -> list[int]:
     [1, 2, 3, 3]
     >>> bubble_sort_recursive([-1, 5, 0, -2])
     [-2, -1, 0, 5]
+    >>> bubble_sort_recursive(["banana", "apple", "cherry"])
+    ['apple', 'banana', 'cherry']
+    >>> bubble_sort_recursive([3.14, 1.5, 2.7])
+    [1.5, 2.7, 3.14]
+    >>> bubble_sort_recursive([1, "two"])  # doctest: +ELLIPSIS
+    Traceback (most recent call last):
+    ...
+    TypeError: ...
     """
     n = len(arr)
     if n <= 1:
@@ -19,7 +38,7 @@ def bubble_sort_recursive(arr: list[int]) -> list[int]:
 
     swapped = False
     for i in range(n - 1):
-        if arr[i] > arr[i + 1]:
+        if arr[i + 1] < arr[i]:
             arr[i], arr[i + 1] = arr[i + 1], arr[i]
             swapped = True