What is a stack in data structure?

A stack in data structure is a linear data structure that follows the Last In, First Out (LIFO) principle. This means the last element inserted into the stack is the first one to be deleted. It allows operations like push (adding elements), pop (removing top elements), and peek or top (viewing top element) to be performed. It is commonly used in programming for function calls, parsing expressions and memory management.

What is a data structure?

A data structure is a specialised format for organising, processing, retrieving and storing data. It refers to a system of organising data in a computer so that it can be used effectively. Examples of such data structures include arrays, linked lists, and trees. These structures enable data to be processed in various ways, such as searching or sorting, depending on the needs of the program or task.

What is structured data?

Structured data is information that is arranged in a highly-organised and predictable manner, following a specific model or schema. It is usually stored in relational databases, where the relationships between various data elements can be effectively exploited. Examples of structured data include numbers, dates, and groupings of words (such as a sentence). This type of data is easy to search and analyse, which makes it highly valuable in fields such as data analysis and machine learning.

What are the differences between structured and unstructured data?

Structured data is organised and formatted in a way that it's easily searchable in relational databases, typically arranged in rows and columns like a spreadsheet. Examples include names, dates and customer data. On the other hand, unstructured data is not organised in a pre-defined manner or does not have a pre-defined data model, making it more difficult to collect, process, and analyse. It includes data like text files, emails, social media posts, video and audio files.

What are types of data structure?

Data structures are categorised into two types: primitive and non-primitive. Primitive types include integers, float, character, and boolean. Non-primitive types can be divided further into linear and non-linear structures. Linear structures consist of arrays, linked lists, stacks, and queues while non-linear structures include trees and graphs.

What is the role of data structures in computer science?

Data structures organise data within a system for efficient use and manipulation. They enable different operations like searching, insertion, deletion, and sorting. Their selection impacts software performance, time, and space savings.

What is an algorithm in the context of data structures?

An algorithm is a step-by-step procedural instruction that interacts with data structures. They define the steps needed to carry out various operations on given data structures, such as sorting, searching, insertion, and deletion.

How do different data structures organise and manage data?

Different data structures manage and organise data in ways matching their nature. For example, an array stores data based on an orderly index number, a stack uses a Last-In-First-Out method, trees and graphs are used for hierarchical data organisation.

What does structured data refer to in the context of data structures?

Structured data refers to formally organised, easy-to-understand data that is highly-organised, easily searchable, and can be readily classified.

What are arrays, stacks, and queues in data structures?

Arrays are fixed-size sequenced collections of same-type elements. Stacks follow a LIFO or FILO order for operations. Queues are containers that follow the FIFO rule for inserting and removing elements.

What are linked lists, trees, and graphs in data structures?

Linked Lists are collections where each element refers to the next. Trees are data structures used to represent hierarchical structures. Graphs are non-linear data structures representing a set of connected objects.

Data Structures: Types, Algorithms & Examples

A closer look at trees as a data structure and their applications will help you comprehend concepts such as binary trees and advanced trees. To emphasise its relevance, the applications of data structures in today's world, notably in software development, will be examined.

Finally, the article will explore structured versus unstructured data, discussing the benefits, hurdles, and impact on data analytics. Together, this comprehensive insight will expand your understanding of the fundamental and complex aspects of data structures in computer science.

Understanding Data Structures in Computer Science

Understanding data structures is a fundamental aspect of learning computer science. In essence, data structures help to organise the data within a system for efficient usage and manipulation. Here, you'll understand the basics of data structures and their essential roles in the realm of computer science.

Introduction to Data Structures and Algorithm

Data Structures, simply put, are different ways to store and organise data to facilitate access and modification. They possess operations like searching, insertion, deletion, and sorting, to name a few. Algorithms, on the other hand, are step-by-step procedural instructions that interact with these data structures. Different types of data structures differ based on the operations you can perform on them and the efficiency of these operations. Here are some common types:

Array
Linked List
Stack
Queue
Tree
Graph

An algorithm is a sequence of instructions or a set of rules that are followed to complete a task. This task can be anything, so long as you can give clear instructions for it.

Consider a bookshelf - When you organize your books by their genre or by author's name, and each time you add or remove a book, you can quickly tell where the book should be placed or removed from. This is an everyday example of Data Structures in action.

Importance and Function of Data Structures

Data structures play an essential role in programming and application development. The usage of data structures allows programmers to write efficient codes that enhance the software's performance. Moreover, choosing the right data structure can lead to significant time and space savings.

Data structures	Functions
Arrays/Lists	Stores data elements based on an orderly index number
Stacks & Queues	Provides access and storage to data in a specific order (Last-In-First-Out or First-In-First-Out)
Trees & Graphs	Used in hierarchical data organization, mapping relationships and connections

How Data Structures organise and manage data

The way data structures manage and organise data varies greatly depending on their nature. They help serve as a blueprint for different types of data, how the data should be stored, and how different operations can be performed on the data.

A Stack, for example, uses a Last-In-First-Out (LIFO) method to organise and manage data. This means the last element added to the stack is the first one to be removed.

The role of Algorithm in Data Structure

Algorithms in data structures play vital roles that aim at performing various operations like searching for data, sorting data elements, inserting and deleting data, etc. Algorithms and data structures go hand in hand because an algorithm defines the steps needed to interact with the data structure. They determine how different operations should be performed on a given data structure. For instance, in searching operation, \[ Binary\ Search\ Algorithm: log_{2} n \] This formula is a mathematical representation for the time complexity of binary search algorithm.

Time complexity is a concept in computer science that deals with the quantification of the amount of time taken by a set of codes or algorithms to process or run as a function of the amount of input. In this case, the binary search algorithm runs in a logarithmic time complexity in the worst case which implies it is highly efficient.

Types of Data Structures

Data structures have been instrumental in giving us the modern digital age that we all enjoy so much. By understanding the data and its representation, we can discover many ways to simplify complex problems. Before diving into different types of data structures, it's essential to distinguish between Structured and Unstructured Data.

Structured Data versus Unstructured Data

In computer science, data is usually classified into structured and unstructured types. The distinction between these two types has critical implications for how the data can be used effectively.

Structured data is formally organised and easy to understand – think of a database filled with names and email addresses. This data is highly-organised, easily searchable and can be readily classified.

On the other hand, unstructured data encompasses data that is not organised in a pre-defined manner or does not have a pre-defined data model, making it much more challenging to collect, process, and analyse. Common examples include social media posts, surveillance footage, or other user-generated content.

It's important to note that:

Structured data is easy to analyse and query using standard programming tools
Unstructured data often requires more complex, advanced tools and processes to analyse effectively

Overview of Common Types of Data Structures

Now that we have an understanding of the basic types of data, let's explore some of the most common types of data structures used in computer science:

Exploring Arrays, Stacks, and Queues

A closer look at these data structures gives us insights into why they are vital tools in any programmer's toolkit.

An array is a fixed-size, sequenced collection of elements of the same data type where each element's location is identified by an indexing system. The simplicity and ease of accessing data make arrays very useful, especially in operations that require random (or direct) access to elements.

Suppose you're creating a simple attendance system. You can use an array to store the names of all students, where each slot in the array represents a seat in the classroom.

A Stack is a type of data structure that follows a specific order in which operations are performed. The order may be LIFO(Last In First Out) or FILO (First In Last Out). Queues, on the other hand, are containers that follow the FIFO rule (First In First Out). An element is inserted at one end and removed from the other end.

In practical terms, Stacks are used in solutions for problems like Backtracking, Expression Evaluation, while Queues are essential in CPU scheduling, Disk Scheduling, and more

Understanding the concept of Linked Lists, Trees, and Graphs

These are more complex data structures that allow us to represent and solve more advanced problems.

Linked Lists are collections of elements where each element has a reference to the next element, making them ideal for representing sequences.

An example of a Linked List can be a Train, where each component car (element) of the train is connected (linked) to the next one.

A Tree data structure is a collection of entities called nodes where each node is a data element. Trees are used for representing hierarchical structures. Lastly, graphs are a non-linear data structure that represents a pictorial structure of a set of objects where some pairs of the objects are connected by links.

In a real-world context, Trees are useful for representing hierarchical relationships like organization structures or file systems, while Graphs are handy for representing networks such as traffic flow, social networks, or web pages.

Tree Data Structures

Tree Data Structures in computer science are hierarchical structures with a specific order of organization. Their main feature is the ability to represent relationships between different nodes or components in a system. In this section, you'll dig deeper into the basics and application of Tree Data Structures, as well as advanced types.

Basics of Tree Data Structure

In simple terms, a tree data structure is a non-linear data structure that emulates a tree structure, with a set of linked nodes. A typical tree structure has a topmost node called the root, and the other nodes are connected by edges to form a parent-child relationship. Every node beneath the root node forms subtrees. Here are some essential terminologies you will encounter in Tree Data Structures:

Node: A single element in a tree data structure.
Root: The one topmost node in the tree with no parent node.
Child Node: A node directly connected to another node when moving away from the root.
Parent Node: The converse concept of a child node.

Then, there is a concept related to tree height and levels:

The height of a Tree is the longest path from the root to the farthest leaf node, whereas level refers to the distance of a node from the root. The root node sits at level 0.

Application and Examples of Tree Data Structure

Tree Data Structures find broad applications across computer systems and are fundamental to understanding the use cases.

Hierarchical Data Organization: Trees are ideal for organizing anything that involves a hierarchy. For example, a computer's file system is a representation of a tree data structure, where each directory represents a tree node, and files inside the directory represent leaf nodes.
HTML DOM: The architecture of HTML DOM (Document Object Model) is a perfect example of a tree data structure. Every HTML tag begins with a root and nests multiple nodes within itself to display structured web content.
Network Routing: Tree data structures are used in router algorithms to determine the quickest route between two networks.

Binary Trees

Binary Tree is a commonly used tree data structure where each node can have at most two children; typically one is referred to as the left child and the other as the right child.

In a binary tree, the maximum number of nodes at any level \(i\) (considering root level as 0), is given by \(2^{i}\). Thus, for a binary tree of height \(h\), the maximum number of nodes is given by the summation \(\sum_{i=0}^{h} {2^{i}}\) which simplifies to \(2^{(h+1)} - 1\).

Uses of Binary Trees:

Binary Search Trees are used in certain data storage applications to ensure quick data retrieval.
They are used in heap implementation, a data structure commonly applied for priority queues.

Advanced Trees: AVL Tree, B-Tree, and Red-Black Tree

These advanced forms of tree structures are enhanced versions designed to address specific problems and optimize performance.

AVL Trees, invented by GM Adelson-Velsky and EM Landis, are self-balancing binary trees where the difference between heights of left and right subtrees cannot be more than one for all nodes. This ensures the depth of the tree remains log proportional to the number of nodes, \(N\) (\( log_{2} N \)), thereby guaranteeing quicker search times.

B-Tree is a self-balancing search tree, commonly used in databases and file systems to maintain sorted data for rapid search, insertions, and deletions. B-Trees reduce the number of disk access since most data are stored in internal nodes and disk access time is considerably higher than main memory access time.

Imagine a library card catalogue. Each card can be thought of as a B-Tree node. Each card (node) can contain multiple entries, and each entry can point to another card (node). This system allows for rapid data access and insertion of new entries.

Finally, the Red-Black Tree is a type of self-balancing binary search tree where every node carries an extra bit of information for balancing after an insertion or removal. This structure helps the tree to maintain a good approximation of a balanced tree, resulting in efficient search, insertion, and deletion operations.

Red-Black Trees are widely used, including the Completely Fair Scheduler (used for CPU scheduling in many operating systems) and the nginx web server.

Practical Applications of Data Structures

Data structures are pivotal in computer science and are employed in virtually every software system or application you use today. From organising a simple set of integers on your computer to the procedural structure of your favourite video game, data structures come into play. Let's explore some practical applications and real-world examples of structured and unstructured data that you may encounter in everyday life.

Real-World Structured Data Examples

There are numerous examples of structured data that you interact with, most likely without even being aware. Here are a few notable ones:

Spreadsheet: A spreadsheet stores data in a structured format. Each cell in a grid corresponds to a particular piece of data, and the structure enables you to perform complex tasks such as calculations, graphs, and pivot tables.
RDBMS: Relational Database Management Systems (RDBMS) such as MySQL, Oracle Database, and MS SQL Server store structured data. This data is stored in well-defined tables with unique identifiers (keys), which can be used to find, update, or delete data rapidly.
Medical Records: A patient's medical records could be a well-structured format where every piece of information has a particular place. This data structure aids in an efficient search and organisation of medical information.
Online Forms: The online forms that you fill out, such as signup or survey forms, they capture structured data. Each field is designed to hold a specific type of data.

Unstructured Data Examples in Daily Life

Conversely, unstructured data is much more prevalent than most people realise. Unstructured data is pervasive in our daily lives, sometimes in very unexpected ways:

Social Media: User-generated content, such as posts, comments, likes, shares on social media platforms like Facebook, Instagram, Twitter, etc., are excellent examples of unstructured data.
Emails: While an email has some structure, its main content is unstructured and could be about anything.
Audio and Video Files: Multimedia files, such as movies, music, and podcasts, are examples of unstructured data as they do not have a pre-defined data model that organises the data.
Text Documents and PDFs: While they may contain internally structured information, as standalone entities, they are considered unstructured since they don't fit into database schemas or models.

How Data Structures drive modern technology

Modern technologies heavily depend on data structures for their successful operation.

For instance, search engines like Google use data structures to store the billions of web pages on the internet. They use an inverted index data structure where every word is associated with a list of web pages that contain it. When searching for entries on a massive database, hash tables are an excellent example of data structure application. They allow for immediate access to entries, saving significant time.

Furthermore, in network technology, a routing table is maintained using a tree data structure that carries information about paths between routers. This tree structure optimises the routing and makes communication faster. Machine Learning algorithms, which are integral to modern technologies such as recommendation systems or autonomous vehicles, use various data structures, including arrays, trees, and graphs. The right choice of data structure dramatically affects the performance of these algorithms.

Role of Data Structure in Software Development

In software development, data structures are like building blocks. They give programmers a means to store, organise and operate on data efficiently.

For instance, in algorithm design, programmers must understand the best data structure that fits their needs. A Sorting algorithm's performance won't be optimal if the appropriate data structure, such as an array or linked list, is not used.

Data structures are also crucial in managing system resources.

For instance, in operating systems, the management of resource allocation and scheduling processes is implemented with the help of queues, stacks, and heaps.
Furthermore, in game development, tree data structures are used for decision-making processes. For example, the game AI uses trees for pathfinding (using Graphs and Dijkstra's algorithm) and decision-making (using Decision Trees).

Finally, in GUI-based application development, data structures like trees and hashes are used for providing features like dropdown menus and windows.

Clearly, the significant role that data structures play in software development, from structuring simple data sets to optimising intricate software requirements, cannot be understated. Understanding and using the right data structure is key to writing efficient and effective software applications.

Structured vs Unstructured Data

To navigate the world of data, it's crucial that you understand the difference between structured and unstructured data. Structured data is well-organised and formatted in a way that it's easily understandable. It is typically stored in rows and columns in databases and can be readily processed and analysed. Examples include data found in relational databases and Excel files.

On the other hand, unstructured data is data that is not organised in a predefined manner or does not have a predefined data model, making it complex to process and analyse. This category includes data like text files, social media posts, audio files, video files, and images.

Advantages and Challenges of Structured Data

The advantages of structured data lie primarily in how easily it can be leveraged.

Easy to enter, store, query, and analyse.
Allows for precise search and analysis due to strict data model.
Enables effective business intelligence through pattern and trend identification.

However, managing structured data comes with its challenges:

Limited in scope as it cannot handle complex data or unforeseen data types.
Entering and maintaining structured data can be time-consuming.
Modifying the data model for additional information can be difficult and resource intensive.

Advantages and Obstacles of Unstructured Data

Unstructured data, due to its inherent flexibility, has its share of advantages:

Can handle virtually any type of data, giving it broad applicability.
Capable of capturing nuanced human inputs, like sentiment in text analytics.
Provides deep insights for decision-making when properly analysed.

Yet it also comes with a diverse set of unique challenges:

Difficult to organise, search, and analyse due to lack of structure.
Can require complex, resource-heavy tools to process and extract useful information.
Data quality can vary greatly, affecting the accuracy of any insights gained.

Analysing the Impact of Unstructured Data on Data Analytics

Data analytics thrives on structured data, but the swift growth of unstructured data is transforming the field. With unstructured data, traditional methods of analysis are often insufficient. There's a growing need for advanced data analytics techniques, such as Natural Language Processing (NLP) for text analysis, computer vision for image recognition, and machine learning for prediction-based modelling.

These advancements enable corporations to delve deeper into their data and extract value in ways that were not possible with structured data alone. However, it also necessitates high-performance computing resources and sophisticated algorithms.

Unstructured data's impact on data analytics is both driving innovation and necessitating a higher level of complexity in analytics tools.

Evolution of Structured Data Management Systems

The journey of structured data management has been one of consistent evolution. The initial database management systems (DBMS) were hierarchical and network DBMS, mostly dealing with structured data. The relational model's arrival marked a significant evolution point, simplifying data management and making data more accessible to non-programming users.

These systems, known as Relational Database Management Systems (RDBMS), still underpin most business applications today. This mature technology, however, continues to evolve. RDBMSs are increasingly incorporating performance and functionality features such as horizontal scalability and unstructured data handling, traditionally associated with NoSQL databases.

Influenced by the cloud data services' rise, RDBMS providers are offering fully managed services to reduce the overheads associated with maintaining large databases. The constant evolution of structured data management systems is a testament to the continuing relevance and importance of structured data in our information-driven world.

Data Structures - Key takeaways

Data Structures are ways to store and organise data to facilitate access and modification. They have operations like searching, insertion, deletion, and sorting. Algorithms are procedural instructions that interact with these structures. Common data structures include Array, Linked List, Stack, Queue, Tree, and Graph.
Data structures improve programming and application performance. Choosing the correct structure can significantly save time and space. Different types are Arrays or Lists (store data elements based on index), Stacks & Queues (access/store data in the specific order), and Trees & Graphs (used in hierarchical data organisation).
Data structures blueprint how data should be stored and how certain operations can be performed on it. For instance, a Stack uses a Last-In-First-Out (LIFO) method to organise and manage data.
There is a large difference between formally organised, searchable, and readily classified structured data which is easy to analyse and query using standard programming tools and unstructured data which lacks a pre-defined data model and requires complex tools and processes for analysis.
Tree data structures are non-linear, emulating tree structures with linked nodes. The topmost node is the root, and other nodes are connected by edges, representing parent-child relationships.

Data Structures

StudySmarter Editorial Team

Understanding Data Structures in Computer Science

Introduction to Data Structures and Algorithm

Importance and Function of Data Structures