Singly, Doubly, Circular

Linked lists come in several variations, each with its own advantages and disadvantages. The Singly Linked List is the simplest form. Each node contains data and a single pointer, `next`, which points to the subsequent node. The last node's `next` pointer is null. They are memory-efficient but can only be traversed in one direction, making operations like finding the predecessor of a node an O(n) task. The Doubly Linked List enhances this by adding a second pointer, `prev`, to each node, which points to the preceding node. This allows for traversal in both forward and backward directions. Operations like deleting a node are more efficient if you have a pointer to the node itself, as you can easily access its previous node in O(1) time. The tradeoff is the extra memory required for the `prev` pointer in each node. A Circular Linked List is a variation where the `next` pointer of the last node points back to the head of the list instead of being null. This can be useful for applications where you need to cycle through a list of items, such as managing a round-robin scheduling queue. A circular list can be singly or doubly linked. Choosing the right type of linked list depends on the specific requirements of the problem, such as traversal direction, ease of deletion, and memory constraints.