Implement a Doubly Linked List

To implement a Doubly Linked List, I first define a Node class containing data, a reference to the next node, and a reference to the previous node. The list itself maintains references to both the head and the tail to optimize performance. For insertion at the head, I create a new node, set its next pointer to the current head, and update the old head's previous pointer to point back to the new node. Then, I update the list's head reference. If the list was empty, the new node also becomes the tail. Conversely, for insertion at the tail, I link the new node to the current tail, update the tail's next pointer, and move the tail reference forward. Deletion requires careful handling; if removing the head, I must ensure the new head's previous pointer is null. Similarly, removing the tail involves updating the new tail's next pointer to null. Throughout this process, I always check for null pointers to avoid runtime errors. This approach ensures O(1) complexity for head and tail operations, which aligns well with Cisco's focus on efficient network processing where low-latency data access is paramount. By maintaining bidirectional links, we enable flexible traversal in both directions, essential for complex networking algorithms.