Advantages and Disadvantages of Doubly Linked List (DLL): A Doubly Linked List (DLL) is a straight information structure that contains an additional a pointer, regularly called the past pointer, along with the following pointer and information which are there in an independently connected list. It tends to be utilized to carry out different information structures like hash-tables, stacks, double trees and so on. DLL can be utilized to execute functionalities, for example, fix/re-try. DLL can be utilized in any product which expects forward and in reverse routes, for example, music players, internet browsers to move between recently visited and current pages and so on. Utilized by a string scheduler in many working frameworks to keep a rundown of every single running interaction. DLL can likewise be utilized in games, for example, addressing a deck of cards.
Students can also find more Advantages and Disadvantages articles on events, persons, sports, technology, and many more.
A linked list is a sequence of data structures that are connected via a link. There are mainly four types of linked lists they are:
- Singly-linked list: Unidirectional linked list that can be traversed in one direction from beginning to end.
- Doubly linked list: a bidirectional linked list that can be traversed in both directions.
- Circular linked list: It is also a type of singly linked list that means unidirectional but the last note heads towards the head node.
- Circular doubly linked list: It is also a type of doubly linked list that means it is bidirectional. It can traverse in both directions.
What is a Doubly linked list?
Doubly linked lists are common for computer science students. A doubly linked list is a linked data structure that consists of nodes that are a set of sequentially linked records. Each node has three fields, two of them are linked fields as they are previous to and next to the nodes in sequence and one of them is a data field. The beginning and end nodes point to the terminator which is a node or null that facilitates traversal of the list. In case there is one sentinel node then the list is circularly linked through it. It can be said as two singly linked lists formed from the same data but in opposite sequences. A doubly linked list is a complex type of linked list.
- Advantages of Doubly linked list
- Disadvantages of Doubly Linked list
- Comparison Table for Advantages And Disadvantages of the Doubly Linked List
- FAQs on Pros and Cons of Doubly linked list
Important Terms Of The Doubly Linked List
Given are a few important terms of the doubly linked list:
- Link: Each link of a linked list can store data.
- Next: Each link of a linked list consists of a link to the next link which is called Next.
- Prev: Each link consists of a link to the previous link which is called Prev.
- Linked lists: It is a connection link.
Few important points to be considered
- A doubly linked list consists of a link element called the First and Last.
- Each link carries one data field and two link fields called Next and Prev.
- Each link is linked with its next link using the Next link.
- Each link is linked with its previous link using the Prev link.
- The last link is null, which is the end of the list.
The Basic Operation of a Doubly Linked List
Following are the basic operations that are supported by a list:
- Deletion: Elements at the beginning of the list will be deleted.
- Insertion: Element is added at the beginning of the list.
- Delete last: The element at the end will be deleted.
- Insert last: Element at the end will be inserted
- Delete: Element will be deleted from the list using a key.
- Insert after: Adds an element after an item on the list.
- Display backward: Display the complete list in a backward manner.
- Display forward: Display the complete list in a forward manner.
Advantages of Doubly Linked List
Listed below are a few advantages of a doubly-linked list.
Let us briefly discuss the advantages of a doubly linked list.
It can be traversed on both sides: It can be traversed from beginning to end and end to the beginning. The doubly linked list name implies that it can be traversed on both sides of the link.
Nodes can be easily deleted: It is easy to delete the nodes for which there are three cases
- Case 1) head node can be deleted
- Case 2) middle node can be deleted
- Case 3) bottom node can be deleted
To delete a node in a doubly-linkedlist follow the given step:
Step 1: Find the previous node of a node to be deleted
Step 2: Change the next of the previous node
Step 3: free memory for the node to be deleted.
Can grow and shrink in size: A linked list has a dynamic structure that can be changed by allocating and deallocating the memory. The size of the array is mostly pre-decided but the size can be changed anytime. So there is no need to give an initial size to the link. The size of the list is generally equal to the nodes in the link.
Help in the implementation of various other data structures: A doubly linked list consist of a link element that helps in establishing various data structure. As we have already seen that each link has a data field and two link fields next and prev. Each link is linked with the next or previous link using the next or previous link.
Easy insertion of new nodes: Insertion in a linked list can be in three ways :
- Insertion in specific nodes
- Insertion in front of the nodes
- Insertion at the end of the node
There are two scenarios for the insertion of nodes either the nodes will be empty or there will be some element in the list.
Reversing is easy: It is easy to reverse the doubly linked list just by swapping the previous with the next pointer of all the nodes. This makes the process simple and easy.
Disadvantages of Doubly Linked List
Let us briefly discuss the above points.
- Consumes extra memory: As there are two pointers previous and next thus it has to consume more memory for working. This is because it has to store the address of the previous node as well as for the next node.
- Random access to elements is not possible: This is because a doubly linked list has to be accessed sequentially either starting from the first node or reversing from the end. Therefore random access to the elements is not possible in doubly-linked lists.
- Require more time: As singly-linked lists have only one pointer this processing takes very less time but a doubly-linked list requires more time as there are two points that not only consume memory but also consume time.
Comparison Table for Advantages And Disadvantages of the Doubly Linked List
| Advantages of doubly linked list | Disadvantages of doubly linked list |
| It can be traversed on both sides | Consumes extra memory. |
| easily deleted | Random access to elements is not possible |
| Can grow and shrink in size | Require more time |
| Help in implementation of various other data structure | – |
| Easy insertion of new nodes | – |
| Reversing is easy | – |
FAQs on Pros and Cons of Doubly linked list
Question 1.
What is a Single linked list?
Answer:
It is a unidirectional list that cannot be traversed in reverse; it can only be traversed one directionally from the head to the last node.
Question 2.
State differently-linked linked lists.
Answer:
Types of linked lists are:
- Singly-linked list
- Doubly linked list
- Circular linked list
- Circular doubly linked list