What is the Difference Between Singly Linked List and Doubly Linked List?

The main difference between a singly linked list and a doubly linked list lies in the structure of their nodes and the way they allow you to traverse and manipulate the list. Here are some key differences between the two:

1. Structure: A singly linked list consists of a collection of nodes, where each node has two fields - data and a link to the next node. In contrast, a doubly linked list has three fields per node - data, a link to the next node, and a link to the previous node.
2. Traversal: In a singly linked list, traversal can be done only in one direction, using the next node link. In a doubly linked list, traversal can be done in both directions, using both the next and previous node links.
3. Insertion and Deletion Complexity: In a singly linked list, the complexity of insertion and deletion is O(n), while in a doubly linked list, the complexity of insertion and deletion is O(1).
4. Memory Consumption: A doubly linked list consumes more memory than a singly linked list, as it requires two pointers per node instead of one.
5. Applications: Singly linked lists are preferred when memory is a concern and searching operations are not needed, such as in the implementation of stacks. Doubly linked lists are preferred when better implementation and searching are required, and they can be used to implement binary trees, heaps, and stacks.
6. Examples: Singly linked lists are used in scenarios like dynamically changing lists, where insertion and deletion of elements occur frequently. A doubly linked list is used in scenarios like a cache, where a pointer to a previous node can be used to invalidate the cache.

Comparative Table: Singly Linked List vs Doubly Linked List

The main differences between singly linked lists and doubly linked lists are as follows: