fix(sorts): support comparable items in pancake sort

Author: berlin880

sorts/pancake_sort.py

@@ -1,3 +1,4 @@
+# sorts/pancake_sort.py   
 """
 This is a pure Python implementation of the pancake sort algorithm
 For doctests run following command:
@@ -14,37 +15,49 @@
 T = TypeVar("T")
 
 
-def pancake_sort[T](arr: Sequence[T]) -> list[T]:
+def pancake_sort(arr: Sequence[T]) -> list[T]:
     """Sort Array with Pancake Sort.
+
     :param arr: Collection containing comparable items
     :return: Collection ordered in ascending order of items
+
     Examples:
     >>> pancake_sort([0, 5, 3, 2, 2])
     [0, 2, 2, 3, 5]
     >>> pancake_sort([])
     []
     >>> pancake_sort([-2, -5, -45])
     [-45, -5, -2]
+    >>> pancake_sort(["banana", "apple", "orange"])
+    ['apple', 'banana', 'orange']
 
-    Time Complexity: (O(n^2))
-    Space Complexity: (O(n))
+    Time Complexity: O(n^2)
+    Space Complexity: O(n)
     """
     cur = len(arr)
+
     while cur > 1:
-        # Find the maximum number in arr
-        mi = arr.index(max(arr[0:cur]))
-        # Reverse from 0 to mi
-        arr = arr[mi::-1] + arr[mi + 1 : len(arr)]
-        # Reverse whole list
-        arr = arr[cur - 1 :: -1] + arr[cur : len(arr)]
+        # Find the maximum item in the unsorted portion.
+        maximum = max(arr[:cur])
+        mi = arr.index(maximum)
+
+        # Move the maximum item to the front.
+        arr = arr[mi::-1] + arr[mi + 1 :]
+
+        # Move the maximum item to its final position.
+        arr = arr[cur - 1 :: -1] + arr[cur:]
+
         cur -= 1
-    return arr
+
+    return list(arr)
 
 
 if __name__ == "__main__":
     import doctest
 
     doctest.testmod()
+
     user_input = input("Enter numbers separated by a comma:\n").strip()
     unsorted = [int(item) for item in user_input.split(",")]
     print(f"{pancake_sort(unsorted) = }")
+