A Doubly Linked List(DLL) is a linear data structure that contains an extra pointer, typically called the previous pointer, together with the next pointer and data which are there in a singly linked list. Below is the image to illustrate the same.
Advantages Of DLL:
- Reversing the doubly linked list is very easy.
- It can allocate or reallocate memory easily during its execution.
- As with a singly linked list, it is the easiest data structure to implement.
- The traversal of this doubly linked list is bidirectional which is not possible in a singly linked list.
- Deletion of nodes is easy as compared to a Singly Linked List. A singly linked list deletion requires a pointer to the node and previous node to be deleted but in the doubly linked list, it only required the pointer which is to be deleted.’
- Doubly linked lists have a low overhead compared to other data structures such as arrays.
- Implementing graph algorithms.
Disadvantages Of DLL:
- It uses extra memory when compared to the array and singly linked list.
- Since elements in memory are stored randomly, therefore the elements are accessed sequentially no direct access is allowed.
- Traversing a doubly linked list can be slower than traversing a singly linked list.
- Implementing and maintaining doubly linked lists can be more complex than singly linked lists.
Uses Of DLL:
- It is used in the navigation systems where front and back navigation is required.
- It is used by the browser to implement backward and forward navigation of visited web pages that is a back and forward button.
- It is also used to represent a classic game deck of cards.
- It is also used by various applications to implement undo and redo functionality.
- Doubly Linked List is also used in constructing MRU/LRU (Most/least recently used) cache.
- Other data structures like stacks, Hash Tables, Binary trees can also be constructed or programmed using a doubly-linked list.
- Also in many operating systems, the thread scheduler(the thing that chooses what process needs to run at which time) maintains a doubly-linked list of all processes running at that time.
- Implementing LRU Cache.
- Implementing Graph algorithms.