Added an add at position subroutiune to linked list (#9020)

* added addAtPosition to simple linked list

* added addAtPosition to simple linked list

* modified the add function to take an optional position command

* fixed type safety errors:

* fixed type safety errors:

* fixed type safety errors:

* fixed type safety errors:

* fixed size error

* fixed size error

* added doctest and updates the else after checking if posiiton argument less than 0 or not

* added doctest and updates the else after checking if posiiton argument less than 0 or not

* fixed the contributing.md mistake

* added doctest for out of bounds position value, both negative and positive

data_structures/linked_list/__init__.py

@@ -21,8 +21,56 @@ class LinkedList:
         self.head: Node | None = None
         self.size = 0
 
-    def add(self, item: Any) -> None:
-        self.head = Node(item, self.head)
+    def add(self, item: Any, position: int = 0) -> None:
+        """
+        Add an item to the LinkedList at the specified position.
+        Default position is 0 (the head).
+
+        Args:
+            item (Any): The item to add to the LinkedList.
+            position (int, optional): The position at which to add the item.
+                Defaults to 0.
+
+        Raises:
+            ValueError: If the position is negative or out of bounds.
+
+        >>> linked_list = LinkedList()
+        >>> linked_list.add(1)
+        >>> linked_list.add(2)
+        >>> linked_list.add(3)
+        >>> linked_list.add(4, 2)
+        >>> print(linked_list)
+        3 --> 2 --> 4 --> 1
+
+        # Test adding to a negative position
+        >>> linked_list.add(5, -3)
+        Traceback (most recent call last):
+            ...
+        ValueError: Position must be non-negative
+
+        # Test adding to an out-of-bounds position
+        >>> linked_list.add(5,7)
+        Traceback (most recent call last):
+            ...
+        ValueError: Out of bounds
+        >>> linked_list.add(5, 4)
+        >>> print(linked_list)
+        3 --> 2 --> 4 --> 1 --> 5
+        """
+        if position < 0:
+            raise ValueError("Position must be non-negative")
+
+        if position == 0 or self.head is None:
+            new_node = Node(item, self.head)
+            self.head = new_node
+        else:
+            current = self.head
+            for _ in range(position - 1):
+                current = current.next
+                if current is None:
+                    raise ValueError("Out of bounds")
+            new_node = Node(item, current.next)
+            current.next = new_node
         self.size += 1
 
     def remove(self) -> Any: