adding quicksort exercise solution

3.py

@@ -0,0 +1,66 @@
+def swap(a, b, arr):
+    if a!=b:
+        tmp = arr[a]
+        arr[a] = arr[b]
+        arr[b] = tmp
+
+# Sorts a (portion of an) array, divides it into partitions, then sorts those
+def quicksort(A, lo, hi):
+  if lo >= 0 and lo < hi:
+    lt, gt = partition(A, lo, hi) # Multiple return values
+    quicksort(A, lo, lt - 1)
+    quicksort(A, gt + 1, hi)
+
+# Divides array into three partitions
+def partition(A, lo, hi):
+  # Pivot value
+  pivot = A[(lo + hi) // 2] # Choose the middle element as the pivot (integer division)
+
+  # Lesser, equal and greater index
+  lt = lo
+  eq = lo
+  gt = hi
+
+  # Iterate and compare all elements with the pivot
+
+  while eq <= gt:
+    if A[eq] < pivot:
+        # Swap the elements at the equal and lesser indices
+        swap(eq, lt, A)
+        # Increase lesser index
+        lt += 1
+        # Increase equal index
+        eq += 1
+    elif A[eq] > pivot:
+        # Swap the elements at the equal and greater indices
+        swap(eq, gt, A)
+        # Decrease greater index
+        gt -= 1
+    else:  # A[eq] == pivot
+        # Increase equal index
+        eq += 1
+
+  # Return lesser and greater indices
+  return lt, gt
+
+elements = [11,9,29,7,2,15,28]
+# elements = ["mona", "dhaval", "aamir", "tina", "chang"]
+quicksort(elements, 0, len(elements)-1)
+print(elements)
+
+tests = [
+        [11,9,29,7,2,15,28],
+        [3, 7, 9, 11],
+        [25, 22, 21, 10],
+        [29, 15, 28],
+        [],
+        [6]
+]
+
+try:
+    # Your script's entry point, e.g., function calls
+    for elements in tests:
+        quicksort(elements, 0, len(elements)-1)
+        print(f'sorted array: {elements}')
+except Exception as e:
+    print(f"Error occurred: {e}")