Update quicksort.py

Author: OmMahajan29

divide_and_conquer/quicksort.py

@@ -1,43 +1,12 @@
 from __future__ import annotations
 
-
-def partition(array: list, low: int, high: int) -> int:
-    """
-    Helper function for quicksort to partition the array.
-
-    >>> array = [3, 2, 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
-
-    for j in range(low, high):
-        if array[j] <= pivot:
-            i += 1
-            array[i], array[j] = array[j], array[i]
-
-    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:
+def quicksort(array: list) -> list:
     """
     Returns a sorted list using the quicksort algorithm.
 
+    Quicksort uses a divide-and-conquer approach to sort the elements
+    by selecting a pivot and partitioning the array.
+
     >>> quicksort([-2, 3, -10, 11, 99, 100000, 100, -200])
     [-200, -10, -2, 3, 11, 99, 100, 100000]
 
@@ -55,19 +24,19 @@ def quicksort(array: list, low: int = 0, high: int | None = None) -> list:
 
     >>> 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)
+    >>> quicksort([2, 1])
+    [1, 2]
+    """
+    if len(array) <= 1:
+        return array
 
-    return array
+    pivot = array[-1]  # Choose the last element as the pivot
+    left = [x for x in array[:-1] if x <= pivot]
+    right = [x for x in array[:-1] if x > pivot]
 
+    return quicksort(left) + [pivot] + quicksort(right)
 
 if __name__ == "__main__":
     import doctest
-
     doctest.testmod()