Enhance double_linear_search doctests with comprehensive examples

Author: JesunAhmadUshno

searches/double_linear_search.py

@@ -5,6 +5,10 @@ def double_linear_search(array: list[int], search_item: int) -> int:
     """
     Iterate through the array from both sides to find the index of search_item.
 
+    This algorithm searches for a target value from both the start and end of the
+    array simultaneously, converging toward the middle. It returns the index of the
+    first match found (prioritizing from the start when both ends match simultaneously).
+
     :param array: the array to be searched
     :param search_item: the item to be searched
     :return the index of search_item, if search_item is in array, else -1
@@ -18,6 +22,45 @@ def double_linear_search(array: list[int], search_item: int) -> int:
     -1
     >>> double_linear_search([1, 5, 5, 10], 10)
     3
+
+    >>> double_linear_search([], 1)
+    -1
+
+    >>> double_linear_search([42], 42)
+    0
+
+    >>> double_linear_search([42], 99)
+    -1
+
+    >>> double_linear_search([1, 2, 3, 4, 5], 3)
+    2
+
+    >>> double_linear_search([1, 2, 3, 4, 5], 1)
+    0
+
+    >>> double_linear_search([1, 2, 3, 4, 5], 5)
+    4
+
+    >>> double_linear_search([10, 10, 10, 10], 10)
+    0
+
+    >>> double_linear_search([-5, -2, 0, 3, 7], -5)
+    0
+
+    >>> double_linear_search([-5, -2, 0, 3, 7], 0)
+    2
+
+    >>> double_linear_search([-5, -2, 0, 3, 7], 7)
+    4
+
+    >>> double_linear_search([1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
+    4
+
+    >>> double_linear_search([1, 2, 3, 4, 5, 6, 7, 8, 9], 9)
+    8
+
+    >>> double_linear_search([100, 200, 300, 400], 250)
+    -1
     """
     # define the start and end index of the given array
     start_ind, end_ind = 0, len(array) - 1