Add Stooge Sort implementation

sorts/stooge_sort.py

@@ -1,39 +1,55 @@
-def stooge_sort(arr: list[int]) -> list[int]:
-    """
-    Examples:
-    >>> stooge_sort([18.1, 0, -7.1, -1, 2, 2])
-    [-7.1, -1, 0, 2, 2, 18.1]
-
-    >>> stooge_sort([])
-    []
-    """
-    stooge(arr, 0, len(arr) - 1)
-    return arr
-
-
-def stooge(arr: list[int], i: int, h: int) -> None:
-    if i >= h:
-        return
-
-    # If first element is smaller than the last then swap them
-    if arr[i] > arr[h]:
-        arr[i], arr[h] = arr[h], arr[i]
-
-    # If there are more than 2 elements in the array
-    if h - i + 1 > 2:
-        t = (int)((h - i + 1) / 3)
-
-        # Recursively sort first 2/3 elements
-        stooge(arr, i, (h - t))
-
-        # Recursively sort last 2/3 elements
-        stooge(arr, i + t, (h))
-
-        # Recursively sort first 2/3 elements
-        stooge(arr, i, (h - t))
-
-
-if __name__ == "__main__":
-    user_input = input("Enter numbers separated by a comma:\n").strip()
-    unsorted = [int(item) for item in user_input.split(",")]
-    print(stooge_sort(unsorted))
+"""
+Stooge Sort - a recursive sorting algorithm.
+
+It is notably slow (worse than bubble sort) but is included here
+for educational purposes to illustrate recursive divide-and-conquer thinking.
+
+Time Complexity: O(n^(log3/log1.5)) ≈ O(n^2.71)
+Space Complexity: O(log n) due to recursion stack
+
+Reference: https://en.wikipedia.org/wiki/Stooge_sort
+"""
+
+
+def stooge_sort(arr: list[int], i: int = 0, j: int = -1) -> list[int]:
+    """
+    Sorts a list in-place using the stooge sort algorithm and returns it.
+
+    >>> stooge_sort([3, 1, 2])
+    [1, 2, 3]
+    >>> stooge_sort([5, 4, 3, 2, 1])
+    [1, 2, 3, 4, 5]
+    >>> stooge_sort([1])
+    [1]
+    >>> stooge_sort([])
+    []
+    >>> stooge_sort([2, 2, 1])
+    [1, 2, 2]
+    >>> stooge_sort([10, -1, 5, 0])
+    [-1, 0, 5, 10]
+    """
+    if len(arr) <= 1:
+        return arr
+
+    if j == -1:
+        j = len(arr) - 1
+
+    if arr[i] > arr[j]:
+        arr[i], arr[j] = arr[j], arr[i]
+
+    if (j - i + 1) > 2:
+        t = (j - i + 1) // 3
+        stooge_sort(arr, i, j - t)
+        stooge_sort(arr, i + t, j)
+        stooge_sort(arr, i, j - t)
+
+    return arr
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+    user_input = input("Enter numbers separated by commas: ")
+    nums = [int(x.strip()) for x in user_input.split(",")]
+    print(f"Sorted: {stooge_sort(nums)}")