Update cocktail_shaker_sort.py

sorts/cocktail_shaker_sort.py

@@ -1,40 +1,62 @@
-""" https://en.wikipedia.org/wiki/Cocktail_shaker_sort """
+"""
+An implementation of the cocktail shaker sort algorithm in pure Python.
 
+https://en.wikipedia.org/wiki/Cocktail_shaker_sort
+"""
 
-def cocktail_shaker_sort(unsorted: list) -> list:
+
+def cocktail_shaker_sort(arr: list[int]) -> list[int]:
     """
-    Pure implementation of the cocktail shaker sort algorithm in Python.
+    Sorts a list using the Cocktail Shaker Sort algorithm.
+
+    :param arr: List of elements to be sorted.
+    :return: Sorted list.
+
     >>> cocktail_shaker_sort([4, 5, 2, 1, 2])
     [1, 2, 2, 4, 5]
-
     >>> cocktail_shaker_sort([-4, 5, 0, 1, 2, 11])
     [-4, 0, 1, 2, 5, 11]
-
     >>> cocktail_shaker_sort([0.1, -2.4, 4.4, 2.2])
     [-2.4, 0.1, 2.2, 4.4]
-
     >>> cocktail_shaker_sort([1, 2, 3, 4, 5])
     [1, 2, 3, 4, 5]
-
     >>> cocktail_shaker_sort([-4, -5, -24, -7, -11])
     [-24, -11, -7, -5, -4]
+    >>> cocktail_shaker_sort(["elderberry", "banana", "date", "apple", "cherry"])
+    ['apple', 'banana', 'cherry', 'date', 'elderberry']
+    >>> cocktail_shaker_sort((-4, -5, -24, -7, -11))
+    Traceback (most recent call last):
+        ...
+    TypeError: 'tuple' object does not support item assignment
     """
-    for i in range(len(unsorted) - 1, 0, -1):
+    start, end = 0, len(arr) - 1
+
+    while start < end:
         swapped = False
 
-        for j in range(i, 0, -1):
-            if unsorted[j] < unsorted[j - 1]:
-                unsorted[j], unsorted[j - 1] = unsorted[j - 1], unsorted[j]
+        # Pass from left to right
+        for i in range(start, end):
+            if arr[i] > arr[i + 1]:
+                arr[i], arr[i + 1] = arr[i + 1], arr[i]
                 swapped = True
 
-        for j in range(i):
-            if unsorted[j] > unsorted[j + 1]:
-                unsorted[j], unsorted[j + 1] = unsorted[j + 1], unsorted[j]
+        if not swapped:
+            break
+
+        end -= 1  # Decrease the end pointer after each pass
+
+        # Pass from right to left
+        for i in range(end, start, -1):
+            if arr[i] < arr[i - 1]:
+                arr[i], arr[i - 1] = arr[i - 1], arr[i]
                 swapped = True
 
         if not swapped:
             break
-    return unsorted
+
+        start += 1  # Increase the start pointer after each pass
+
+    return arr
 
 
 if __name__ == "__main__":