Linked List - An Intro

A linked list is a sequence of elements, where each element has a reference to the next element in the list. This type of data structure is useful for storing collections of data that don't need to be in a specific order and where the size of the collection is not predetermined.

To understand linked lists, it's important to familiarize oneself with the following terms:

• Link: Each link in a linked list can hold a piece of data called an element.
• Next: Each link in a linked list has a reference to the next link, known as Next.
• LinkedList: A linked list consists of a connection to the first link, known as First.

Real Life Example of Linked List

One real-life example of a linked list is a chain of paper clips, where each paper clip is linked to the next paper clip by a small piece of wire. This chain of paper clips is an example of a singly linked list, with each paper clip representing an element in the list and the wire representing the reference to the next element.

Other real-life examples of linked lists include a list of tasks on a to-do list, where each task is linked to the next task, and a list of items on a grocery list, where each item is linked to the next item. In each of these examples, the linked list allows for flexible and efficient insertion and deletion of elements, as well as efficient access to elements based on their position in the list.

Linked list and Arrays

Linked lists and arrays are both data structures that are used to store and manipulate collections of data. However, they have some significant differences that make them suitable for different use cases.

One major difference between linked lists and arrays is the way they are stored in memory. Arrays are stored in contiguous blocks of memory, while linked lists are made up of a series of nodes that are scattered throughout memory. This means that arrays are more efficient for accessing elements based on their position, while linked lists are more efficient for inserting and deleting elements.

Another difference between linked lists and arrays is the way they handle changes in size. Arrays have a fixed size, which means that once an array is created, it cannot be resized. Linked lists, on the other hand, can be resized dynamically, as they do not have a fixed size. This makes linked lists more flexible than arrays when it comes to handling changes in the size of the collection.

Despite these differences, linked lists and arrays have some similarities as well. Both data structures are used to store and manipulate collections of data, and they both provide efficient access to elements based on their position in the collection.

There are several reasons why a linked list might be preferred over an array in certain situations:

1. Dynamic size: Linked lists can be resized dynamically, as they do not have a fixed size like arrays do. This makes them more flexible than arrays when it comes to handling changes in the size of the collection.

2. Insertion and deletion: Linked lists are more efficient than arrays for inserting and deleting elements, as they do not require the shifting of elements to make room for new elements or to fill the gap left by deleted elements.

3. Memory efficiency: Linked lists are more memory efficient than arrays in some cases, as they do not require contiguous blocks of memory like arrays do. This can be beneficial when dealing with large collections of data.

Advantages of linked lists:

1. Dynamic size: Linked lists can be resized dynamically, as they do not have a fixed size like arrays do. This makes them more flexible than arrays when it comes to handling changes in the size of the collection.

2. Insertion and deletion: Linked lists are more efficient than arrays for inserting and deleting elements, as they do not require the shifting of elements to make room for new elements or to fill the gap left by deleted elements.

3. Memory efficiency: Linked lists are more memory efficient than arrays in some cases, as they do not require contiguous blocks of memory like arrays do. This can be beneficial when dealing with large collections of data.

Disadvantages of linked lists

1. Access time: Linked lists are not as efficient as arrays for accessing elements based on their position. This is because linked lists do not have a fixed size and elements are scattered throughout memory, while arrays are stored in contiguous blocks of memory and can be accessed using an index.

2. Memory overhead: Linked lists require more memory than arrays to store the same number of elements, as each element in a linked list requires an additional reference to the next element in the list.

3. Complexity: Linked lists can be more complex to implement and work with than arrays, as they require the use of pointers and require more care when inserting and deleting elements.

Applications of linked list

Linked lists are a useful data structure for storing and manipulating collections of data in a flexible and efficient manner. They are often used in the following applications:

1. Dynamic memory allocation: Linked lists are commonly used in memory allocation schemes, where they are used to track available blocks of memory and to allocate and deallocate blocks as needed.
2. Stacks and queues: Linked lists are often used to implement stacks and queues, as they allow for efficient insertion and deletion of elements at the front and back of the list.
3. Graphs and trees: Linked lists are often used to represent graphs and trees, as they allow for the efficient insertion and deletion of nodes and edges in these data structures.
4. List-based searching: Linked lists are useful for list-based searching algorithms, as they allow for efficient insertion and deletion of elements and provide efficient access to elements based on their position in the list.
5. Database systems: Linked lists are used in database systems to store data and to implement index structures, as they allow for efficient insertion and deletion of elements and provide efficient access to elements based on their position in the list.
6. Polynomials and sparse matrices: Linked lists can be used to represent and perform operations on polynomials, and to represent sparse matrices.

Representation of Linked List

To declare a linked list in C, you can use a structure to represent each node in the list and a pointer to the first node in the list. Here is an example of how you might declare a linked list of integers in C:

struct node {
   int value;
   struct node *next;
};

struct node *head;

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