A Comprehensive Guide To Linked List Data Structure

Linked List is a type of data structure used in the C++ language. It stores elements in individual containers called nodes. These elements are not assigned contiguous memory locations.

Linked List is predominantly used when there is a dynamic data whose volume is hard to decipher since it tends to change during the execution of the program. And generally, a linked list data structure is implemented with the help of pointers.

In order to (easily) implement Linked List and perform different operations using C++, C or any other languages, one must understand the anatomy, working concept, advantages and applications of it.

So here, we have created this comprehensive guide on Linked List In Data Structure which will help you understand all the concepts behind it.

Understanding Linked List Data Structure

Anatomy of Linked List 

The interconnection of nodes forms a linked list. Each of these nodes consists of two components: ‘data’ and ‘next’.

The data component holds the element you define as the input while the next component stores the address of the next node. The first node in the linked list data structure is called the head and the last node is called the tail.

It must be understood that the last node wouldn’t point to another node and thus its address field would be null, that is, the tail node’s next component would be null.

Also, as mentioned earlier, the length of the linked list can either shrink or increase with the execution of the program.

Types Of Linked List Data Structure

There are basically three different types of linked list data structures. They are as follows:

  • Singly Linked List
  • Doubly Linked List
  • Circular Linked List

In a singly linked list, every node has a link only to the next subsequent node.

Singly Linked List Data Structure

On the flip side, in a doubly linked list, every node has a link to both the forward and backward nodes.

Doubly Linked List Data Structure

In much contrast to the two, the circular linked list form a loop between the defined nodes. That is, the nodes that are linked by pointers such that they form a circle, are what comprise the circular linked list. Here, the tail node’s next component addresses the head node’s address to form the circle.

Circular Linked List Data Structure

Basic Operations of Linked List

  • Creation
  • Insertion
    • At the start
    • At the end
    • At a particular position
  • Deletion
    • At the start
    • At the end
    • At a particular position
  • Displaying
  • Searching

Have a quick look at these basic operations of Linked List.

Merits of Linked List

Since linked list data structure is dynamic in nature, you needn’t allocate memory before execution, rather during the run time, the memory would be allocated depending on the behavior of the linked list (shrinks or expands).

Also, creating linked list data structures and inserting and deleting elements are much flexible. You can add a node at your position of interest and even remove it when you deem. Unlike an array, here you needn’t shift the nodes. You can just update the list.

And most importantly, since you needn’t allocate memory during compilation, the required memory is allocated adeptly during the run time. Thus, memory utilization is efficient here.

Basic Application Of A Linked List

Consider a scenario where you are writing a program that stores the revenue generated by selling Classmate notes for the year 2020. Now, assume that you’ve forgotten that it’s a leap year.

So, you simply go ahead with the memory allocation logic of int revenue[365].

So, let’s say that at run time you realize that there are 366 days in the year 2020. Now, how will you store the revenue for February 29, 2020? You’re lacking a memory space here.

Now, let’s take this situation where you need to only store the quarterly revenue records. Here you’re wasting memory.

This is precisely why you need to implement linked list for your programs as required by your application. By implementing a linked list data structure, you can either create a memory or even free memory.

There are a few more applications:

  • Implementation of Stack.
  • Implementation of Queue.
  • Representation and arithmetic operations of polynomials.
  • Dynamic memory allocation.

Limitations of Linked List

Despite its functional benefit as mentioned above, linked list data structure has certain limitations which we shall look into.

We saw above that memory allocation can be made efficient. Nevertheless, to store a node you need to allocate extra memory due to the interlinking by pointers. Thus, compared to arrays, linked lists utilize more memory.

It is also quite hard to traverse a linked list. This is because random accessing of nodes is prohibited, unlike array where we can access an array element via index. For instance, to access the node ‘j’ we would have to traverse all the way from node ‘a’ to node ‘j’. Therefore, the time complexity is increased.

Winding Up

Linked lists are dynamic data structures whose memory can be manipulated at run time. They are of three types: singly-linked lists, doubly linked lists, and circular linked lists. Some of the basic operations you can try with linked lists are creating, inserting, deleting, displaying and searching. While memory allocation is deemed merit, memory utilization by linked list has been deemed a demerit. Nevertheless, you can implement a linked list for a wide range of dynamic applications.

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