Update quicksort.py

Author: OmMahajan29

divide_and_conquer/quicksort.py

@@ -1,17 +1,25 @@
 from __future__ import annotations
 
-
 def partition(array: list, low: int, high: int) -> int:
-    """Helper function for quicksort to partition the array.
+    """
+    Helper function for quicksort to partition the array.
+
     >>> array = [3, 2, 1]
-    >>> partition(array, 0, len(array) - 1)
+    >>> idx = partition(array, 0, len(array) - 1)
+    >>> idx
     0
     >>> array
     [1, 2, 3]
+
     >>> array = [12, 4, 5, 2, 3]
     >>> idx = partition(array, 0, len(array) - 1)
     >>> array[:idx], array[idx], array[idx+1:]
     ([2, 3, 4], 5, [12])
+
+    >>> array = [2, 1]
+    >>> idx = partition(array, 0, len(array) - 1)
+    >>> array
+    [1, 2]
     """
     pivot = array[high]
     i = low - 1  # Pointer for the smaller element
@@ -24,18 +32,38 @@ def partition(array: list, low: int, high: int) -> int:
     array[i + 1], array[high] = array[high], array[i + 1]
     return i + 1
 
-
 def quicksort(array: list, low: int = 0, high: int | None = None) -> list:
+    """
+    Returns a sorted list using the quicksort algorithm.
+
+    >>> quicksort([-2, 3, -10, 11, 99, 100000, 100, -200])
+    [-200, -10, -2, 3, 11, 99, 100, 100000]
+
+    >>> quicksort([1, 2, 3, 4, 5])
+    [1, 2, 3, 4, 5]
+
+    >>> quicksort([5, 4, 3, 2, 1])
+    [1, 2, 3, 4, 5]
+
+    >>> quicksort([-200])
+    [-200]
+
+    >>> quicksort([])
+    []
+
+    >>> quicksort([10000000, 1, -1111111111, 101111111112, 9000002])
+    [-1111111111, 1, 9000002, 10000000, 101111111112]
+    """
     if high is None:
         high = len(array) - 1
+
     if low < high:
         pivot_index = partition(array, low, high)
         quicksort(array, low, pivot_index - 1)
         quicksort(array, pivot_index + 1, high)
-    return array
 
+    return array
 
 if __name__ == "__main__":
     import doctest
-
     doctest.testmod()