Implementing fundamental operations: insertion (at head, tail, middle) and deletion.
A solid understanding of a linked list requires proficiency in its fundamental operations: insertion, deletion, and traversal. Traversal is the simplest, involving starting at the head and following the `next` pointers until you reach a null pointer. Insertion can happen at three main locations. Inserting at the head is an O(1) operation: create a new node, set its `next` pointer to the current head, and then update the head to point to the new node. Inserting at the tail requires traversing the entire list to find the last node, making it an O(n) operation (unless a separate tail pointer is maintained, which makes it O(1)). Inserting in the middle requires traversing to the node just before the desired insertion point, and then adjusting pointers to link the new node into the list. Deletion also varies. Deleting the head node is O(1). Deleting a node in the middle or at the end requires finding the node *before* the one to be deleted to adjust its `next` pointer, which is an O(n) operation. For a doubly linked list, deletion is more efficient if you have a pointer to the node to be deleted, as you can access its previous node in O(1) time to update pointers. These basic operations are the building blocks for solving more complex linked list problems.