Dynamic Data Allocation Made Easy with Linked Lists

Introduction

Linked lists are a common data structure in computer science that is used to store data collections. In this blog, we'll go over the fundamentals of linked lists, such as how they're built, how nodes and pointers are used, and the various types of linked lists. We'll also go over common linked list operations, as well as the benefits of using them in programming.

Linked lists are made up of nodes, each of which contains data as well as a reference to the next node in the list. Pointers are used to connect nodes in the list, indicating which node comes before or after a given node. There are three kinds of linked lists: singly linked lists, doubly linked lists, and circular linked lists.

Types Of Linked List

Singly Linked List: A singly linked list is a type of linked list in which each node points to the next node in the chain. Consider the following example of a singly linked list with four nodes:

In this illustration, head points to the list's root node. Data for the node and a pointer to the following node in the list are both present in each node of the list. The list's last node, which refers to None, denotes its conclusion.

The above-described single linked list's structure is depicted in the following block diagram:

In this figure, each box substitutes in for a node in the list, including the data and next pointer. The pointers between nodes are represented by the arrows. At the top of the graphic, the first node in the list is shown by the head pointer.

With each node pointing to the following node in the list, this block diagram illustrates the structure of a singly linked list. This makes it possible to traverse the list quickly in a single direction, from the head to the last node.

Doubly Linked List: A doubly linked list is a type of linked list in which each node points to both the next and previous nodes in the list. Consider the following example of a doubly linked list with four nodes:

The arrows in this diagram represent pointers between nodes. Each node in the list has two pointers: a next pointer that points to the node after it, and a prev pointer that points to the node before it. The None values at the beginning and end of the list represent the list's head and tail, respectively.

Circular Linked List: A circular linked list is a type of linked list in which the last node points back to the first, resulting in a loop. Here's an illustration of a circular linked list with four nodes:

In this example, the last node's next pointer (node4) points back to the first node (node1), forming a loop that connects the list's end to its beginning.

Representation Of Linked List

A linked list is a data structure made up of nodes, each of which contains a data element and a pointer to the next node in the sequence. The first node in the sequence is referred to as the head of the list, while the last node is referred to as the tail of the list.

A linked list in Java is represented by a class that defines the node structure and another class that defines the linked list structure. Here's an example of how to do it:

Linked Lists and Its Utilities

• Dynamic Data Structure: Unlike arrays, linked lists can expand and contract as needed. New nodes can be added to the list, and existing nodes can be removed, without affecting the overall size of the data structure. This makes linked lists useful in situations where the size of the data is unknown ahead of time or where the data must be changed frequently.

• Efficient Insertions and Deletions: Because linked list nodes are not stored in contiguous memory locations, inserting or deleting a node does not necessarily require shifting the positions of the other nodes. This means that insertions and deletions can be done faster than in arrays.

• Easy To Implement: Most programming languages, including Java, C, C++, Python, and others, can easily implement linked lists. The code for manipulating a linked list is frequently simpler and easier to understand than the code for manipulating arrays.

• Versatile: Other abstract data types, such as stacks, queues, and trees, can be implemented using linked lists. They can also be used to solve a variety of programming problems, such as text processing and graph traversal.

Time Complexity

The following table shows the time complexity of various operations on a singly linked list, assuming an n-node list:

Linked Lists and Its Applications

• Implementing Dynamic Data Structures: Linked lists are used to implement stacks, queues, trees, and graphs, among other dynamic data structures. Linked lists are an excellent choice for these applications due to their ease of adding and removing elements.

• Implementing Memory Allocation: Operating systems, compilers, and other software make use of dynamic memory allocation. Linked lists can be used to keep track of free memory blocks and allocate them to applications as needed.

• Implementing File Systems: In file systems, linked lists are used to keep track of files and directories. Each file or directory is represented by a node, and the linked list allows for efficient file system navigation.

• Implementing Hash Tables: In hash tables, linked lists are used to handle collisions. When two keys hash to the same index, the values associated with those keys are stored in a linked list.

• Managing Large Datasets: To manage large datasets that cannot fit in memory, linked lists are used in data structures such as streams and queues.

• Implementing Garbage Collection: In garbage collection algorithms, linked lists are used to keep track of which objects are no longer needed and can be deleted.

Advantages Of Linked Lists over Arrays

• Dynamic Size: Linked lists can expand and contract dynamically, whereas arrays have a fixed size i.e., set at the start. Because of this, linked lists are a good choice when the size of the data is unknown or changes over time.

• Insertion and Deletion: In a linked list, inserting or deleting an element is much faster than in an array. To fill the gap in an array, elements must be shifted up or down, which can be a time-consuming operation. Adding or removing an element from a linked list requires only a few pointers to be updated.

• Efficient Memory Allocation: Linked lists consume less memory than arrays. Memory must be allocated for the entire array upfront when using an array, even if some of the elements are unused. Only the elements that are actually used are allocated memory in linked lists.

• Easy To Implement Other Data Structures: Other data structures, such as stacks, queues, trees, and graphs, are built on linked lists. Using a linked list instead of an array makes it much easier to implement these data structures.

• Flexibility: Linked lists can be singly or doubly linked, and they are easily adaptable to the needs of the specific application. As a result, they are more adaptable than arrays.

This was all about some basic concepts regarding Linked List. In the upcoming blogs we will be covering about Linked Lists and its Implementation with code syntax.