Introduction to Data Structure

Data structure refers to the way data is organized and stored in a computer. It includes a wide variety of concepts and techniques used to organize data so that it can be accessed and manipulated efficiently. Data structure is very important in software development because it affects the performance and reliability of the system being built.

B. Motivation for Using Linked List

Linked list is one of the data structures that is very flexible and useful in situations where the size and structure of the data can change dynamically. When we use a linked list, we don't need to allocate memory continuously as it happens with arrays. Moreover, linked lists allow easy insertion or deletion of elements without the need to move other elements, which makes it suitable for various applications such as queues, stacks, and many more.

C. Tutorial Objectives

The objective of this tutorial is to provide a comprehensive understanding of linked lists, including basic definitions, types of linked lists, basic implementation, and advantages and disadvantages of using them. By understanding the basic concepts and techniques of linked lists, the reader is expected to be able to use these data structures efficiently in software development and understand when and how to use linked lists in various contexts.

Definition of Linked List

In this section, we will define a linked list, discuss the main characteristics that distinguish it from other data structures, and compare it to an array to understand the advantages and disadvantages of each.

A. Definition of Linked List

Linked list is a linear data structure consisting of a series of elements called “nodes”, where each node is connected to the next node in a specific order. Each node consists of two main parts: the data being stored and a reference to the next node in the sequence. This allows dynamic memory allocation and does not require static memory allocation as is the case with arrays.

B. Characteristics of Linked List

The main characteristics of a linked list are its flexibility in memory allocation and deallocation, and its ability to store and access data sequentially without requiring sequential memory allocation. Linked lists are also dynamic, which means new elements can be added or removed from the linked list easily.

C. Comparison with Arrays

The comparison between linked lists and arrays is a common debate in the programming world. Arrays are static data structures that allocate memory sequentially to their elements, whereas linked lists use a dynamically connected node structure. The advantages of arrays include random access to elements, while the advantages of linked lists include the ability to insert and remove elements efficiently without moving other elements. The decision to use either one depends on the specific needs and characteristics of the application being developed.

Types of Linked List

Linked lists have several types, each of which has different characteristics and uses. In this section, we will discuss the three main types of linked lists: single linked list, double linked list, and circular linked list.

A. Single Linked List

Single linked list is the most basic type of linked list where each node is connected to the next node in a linear order. Each node has two parts: the data stored and a reference to the next node in the sequence. Single linked lists have no reference back to the previous node, so navigation can only be done from front to back. It is a simple and efficient data structure for applications that require insertion or deletion of elements at the end of the linked list.

B. Double Linked List

A double linked list is an extension of a single linked list where each node has two references: one to the previous node and one to the next node in the sequence. By having a reference to the previous node, the double linked list allows both forward and backward navigation, which makes it more flexible than the single linked list. However, it also requires additional memory allocation to store the additional references, so it can increase memory overhead.

C. Circular Linked List

Circular linked list is a linked list where the last node is connected back to the first node, forming a closed circle. In a circular linked list, there is no last element, and navigation operations continue to loop from the first node to the last node and vice versa. This makes it possible to create cyclic data structures and can be used in applications such as scheduling or circular buffers.

Each type of linked list has different uses and applications depending on the specific needs of the application being developed. By understanding the differences between these types of linked lists, developers can choose the type that best suits the needs and characteristics of their application.

Basic Implementation of Single Linked List

The basic implementation of a single linked list involves some basic operations such as creation of an empty linked list, addition and deletion of elements at the beginning and end, and insertion and deletion of elements in the middle of the linked list. The following is a further discussion on this implementation:

A. Node Structure

In the basic implementation of a single linked list, the node structure plays a key role. Each node in a single linked list stores a data element and has a reference to the next node in the sequence. This node structure is usually defined as a structure or class in the programming language used. In general, a node consists of two main components: the desired data, such as an integer, string, or object, and a reference to the next node in the linked list.

At a minimum level, the node structure in a single linked list has two data fields: one to store the actual data to be stored in the linked list, and the other to point to the next node in the sequence. In programming languages such as C or C++, a node structure can be defined as a struct that has two data fields: one to store the data element (for example, an integer, character, or object), and the other to store the address of the next node in the linked list.

In object-oriented programming languages such as Java or Python, a node structure is usually defined as a class that has member variables to store data and references to the next node. For example, in Java, a Node class can be defined with member variables to store data and references to the next node, while in Python, a Node class can be defined with a data attribute and a next attribute for the same purpose.

The node structure must be carefully designed to ensure the efficiency of data storage and access to linked list elements. Understanding the node structure is an important step in understanding how linked lists work and allows developers to properly implement basic linked list operations in their code.

B. Empty Linked List Creation

Creating an empty linked list is an important first step in implementing a single linked list. When creating an empty linked list, we must initialize a variable or object that points to the first node in the linked list as a value indicating that the linked list has no elements. This step is important because it determines the initial state of the linked list before elements are added.

In programming languages such as C or C++, the creation of an empty linked list involves the declaration of a pointer variable that points to a predefined node data type. This pointer is then set to a null value or a special value that indicates an empty linked list. For example, in C, we can declare a pointer to a node as follows: struct Node* head = NULL;.

While in object-oriented programming languages such as Java or Python, creating an empty linked list often involves creating an object of a previously defined linked list class. This object represents the linked list and has a member variable that points to the first node in the linked list. In Java, we can create an empty linked list object with this syntax: LinkedList myList = new LinkedList();. Whereas in Python, we can create an empty linked list by using the constructor of the linked list class: myList = LinkedList().

This step of creating an empty linked list provides the foundation for subsequent operations, such as adding or removing elements. By having an empty linked list, we can start the process of building and managing linked lists according to our application needs.