# Applications of Different Linked Lists in Data Structure

## What is a Linked list?

A linked list is a data structure that consists of a sequence of elements, where each containing a reference or ("link") to the next element in the list. The first element is called the head and the last element is called the tail. Linked lists are often used in place of arrays when the size of the data set is unknown or when the data is frequently inserted or deleted. They can also be useful for implementing other data structures such as stacks and queues.

## Types of Linked Lists

**There are several types of linked lists. Some of them are as follows:**

**Singly Linked List:**In this type of linked list, each element (also known as a node) has a reference only to the next element in the list.**Doubly Linked List:**In this type of linked list, each element has a reference to both the next and previous elements in the list. This allows for easier traversal in both directions.**Circular Linked List:**In this type of linked list, the last element points back to the first element, effectively forming a circle. This can be implemented as either a singly or doubly linked list.**Skip List:**In this type of linked list, each element also has one or more forward pointers to elements further down the list, allowing for faster traversal of large lists.**XOR Linked List:**In this type of linked list, each element stores the memory address of the next element using the XOR operation. This allows for the reduction of memory usage and faster traversal.**Multi-linked List:**In this type of linked list, each element can have multiple links to other elements in the list. This can be useful in certain types of graph-based algorithms.

## Applications of Linked Lists

**Linked lists are a type of data structure that can be used in a variety of applications, such as:**

**Dynamic memory allocation:**Linked lists can be used to allocate and deallocate memory dynamically, as new elements can be added or removed from the list as needed.**Data traversal:**Linked lists can be used to traverse large amounts of data, as each element in the list contains a pointer to the next element.**Stacks and Queues:**Linked lists can be used to implement stacks and queues, which are commonly used in computer science and programming.**Reverse order traversing:**Linked list can be used to traverse elements in reverse order.**Multi-way branching:**Linked list can be used to implement multi-way branching.**Graph data structure:**Linked list can be used to implement graphs and represent the edges in graph data structures.**Hash Table:**Linked lists can be used in hash table implementation as a way to handle collisions.**Circular linked list:**Circular linked list can be used for implementation of circular queue.**Insertion and deletion:**Linked lists allow for efficient insertion and deletion of elements at any point in the list, as only the links between elements need to be updated.**Variable size:**Linked lists can be used when the size of the data set is unknown or when the size may change frequently, as the memory for a linked list is allocated as needed.**Sparse Matrix:**Linked lists can be used to represent large sparse matrix, where only non-zero elements are stored.**Polynomial Representation**: Linked lists can be used to represent polynomials, where each element represents a term in the polynomial.**LRU Cache:**Linked list can be used to implement LRU Cache where elements are always added and deleted from the head and tail of the list respectively.

### Applications of Singly Linked Lists

**Singly linked lists have a number of applications. Some of them are as follows:**

**Stacks:**Singly linked lists can be used to implement a last-in, first-out (LIFO) stack data structure, where elements are added and removed from the top of the stack.**Queues:**Singly linked lists can be used to implement a first-in, first-out (FIFO) queue data structure, where elements are added to the tail of the list and removed from the head.**Dynamic memory allocation:**Singly linked lists can be used for dynamic memory allocation, where new elements are added to the list as needed and de-allocated when they are no longer needed.**Hash tables:**Singly linked lists can be used to implement hash tables with chaining, where each element in the hash table is a linked list node that stores the key-value pair.**Sparse matrix representation**: Singly linked lists can be used to represent sparse matrices, where only the non-zero elements are stored.**Linked List based Merge Sort:**Singly linked lists can be used to implement Merge Sort, where the list is divided into two parts and then merge back by comparing the elements.**Graphs:**Singly linked lists can be used to represent the edges in a graph data structure.**Circular buffer:**Singly linked list can be used to implement a circular buffer where head and tail both points to the same element, and when buffer is full, it overwrites the oldest element.

### Applications of Doubly Linked List

**Doubly linked lists have a number of applications. Some of them are as follows:**

**Insertion and deletion:**Doubly linked lists allow for efficient insertion and deletion of elements at any point in the list, as only the links between elements need to be updated.**Stacks and Queues:**Doubly linked lists can be used to implement stack and queue data structures, which are commonly used in computer science.**Browser history:**Doubly linked lists can be used to implement the forward and backward navigation of web browsers.**LRU Cache:**Doubly linked list can be used to implement LRU Cache, where elements are always added and deleted from the head and tail of the list respectively.**Graphs:**Doubly linked lists can be used to represent the edges in a graph data structure.**Undo-Redo functionality:**Doubly linked lists can be used to implement undo-redo functionality in software, where each element in the list represents a state of the program.**Circular buffer:**Doubly linked list can be used to implement a circular buffer where head and tail both points to the same element, and when buffer is full, it overwrites the oldest element.

### Applications of Circular Linked Lists

**Circular linked lists have a number of applications. Some of them are as follows:**

**Queues:**Circular linked lists can be used to implement a first-in, first-out (FIFO) queue data structure, where elements are added to the tail of the list and removed from the head. This can be useful in situations where the queue needs to be circular, i.e. when the end of the list is reached; the next element is the first element.**LRU Cache:**Circular linked list can be used to implement LRU Cache, where elements are always added and deleted from the head and tail of the list respectively.**Music player:**A circular linked list can be used to implement a music player, where the next song plays after the last song.**Game development:**Circular linked list can be used in game development, where a circular linked list can be used to implement a circular queue for storing the inputs.**Token ring:**Circular linked list can be used to implement token ring networks, where the data is passed from one node to another in a circular fashion.**Round-robin scheduling:**Circular linked list can be used in round-robin scheduling, where the CPU time is allocated to each process in a circular fashion.