Data Structures 101: Introduction to Data Structures and Algorithms

Programming is all about data structures and algorithms. Data structures are used to hold data while algorithms are used to solve the problem using that data.
Data structures and algorithms (DSA) goes through solutions to standard problems in detail and gives you an insight into how efficient it is to use each one of them. It also teaches you the science of evaluating the efficiency of an algorithm. This enables you to choose the best of various choices.

What are Data Structures?

Data structure is a storage that is used to store and organize data. It is a way of arranging data on a computer so that it can be accessed and updated efficiently.
Depending on your requirement and project, it is important to choose the right data structure for your project. For example, if you want to store data sequentially in the memory, then you can go for the Array data structure.

Why Data Structure?

Knowledge about data structures help you understand the working of each data structure. And, based on that you can select the right data structures for your project.
This helps you write memory and time efficient code.

Types of Data Structure

Basically, data structures are divided into two categories:

• Linear data structure
• Non-linear data structure

Let's learn about each type in detail.

Linear data structures

In linear data structures, the elements are arranged in sequence one after the other. Since elements are arranged in particular order, they are easy to implement.
However, when the complexity of the program increases, the linear data structures might not be the best choice because of operational complexities.

Popular linear data structures are:

1. Array Data Structure

In an array, elements in memory are arranged in continuous memory. All the elements of an array are of the same type. And, the type of elements that can be stored in the form of arrays is determined by the programming language.

1. Stack Data Structure

In stack data structure, elements are stored in the LIFO principle. That is, the last element stored in a stack will be removed first.
It works just like a pile of plates where the last plate kept on the pile will be removed first.

1. Queue Data Structure

Unlike stack, the queue data structure works in the FIFO principle where first element stored in the queue will be removed first.
It works just like a queue of people in the ticket counter where first person on the queue will get the ticket first.

1. Linked List Data Structure

In linked list data structure, data elements are connected through a series of nodes. And, each node contains the data items and address to the next node.

Non linear data structures

Unlike linear data structures, elements in non-linear data structures are not in any sequence. Instead they are arranged in a hierarchical manner where one element will be connected to one or more elements.
Non-linear data structures are further divided into graph and tree based data structures.

1. Graph Data Structure

In graph data structure, each node is called vertex and each vertex is connected to other vertices through edges.

1. Trees Data Structure

Similar to a graph, a tree is also a collection of vertices and edges. However, in tree data structure, there can only be one edge between two vertices.
Popular Tree based Data Structure

• Binary Tree
• Binary Search Tree
• AVL Tree
• B-Tree
• B+ Tree
• Red-Black Tree

What is an Algorithm?

An algorithm is a finite set of instructions or logic, written in order, to accomplish a certain predefined task. Algorithm is not the complete code or program, it is just the core logic(solution) of a problem, which can be expressed either as an informal high level description as pseudocode or using a flowchart.

Every Algorithm must satisfy the following properties:

Input- There should be 0 or more inputs supplied externally to the algorithm.
Output- There should be atleast 1 output obtained.
Definiteness- Every step of the algorithm should be clear and well defined.
Finiteness- The algorithm should have finite number of steps.
Correctness- Every step of the algorithm must generate a correct output.

An algorithm is said to be efficient and fast, if it takes less time to execute and consumes less memory space. The performance of an algorithm is measured on the basis of following properties :

Time Complexity
Space Complexity

Informally, an algorithm is nothing but a mention of steps to solve a problem. They are essentially a solution.

In computer programming terms, an algorithm is a set of well-defined instructions to solve a particular problem. It takes a set of input and produces a desired output. For example,
An algorithm to add two numbers:

1. Take two number inputs
2. Add numbers using the + operator
3. Display the result

Qualities of Good Algorithms

Input and output should be defined precisely.
Each step in the algorithm should be clear and unambiguous.
Algorithms should be most effective among many different ways to solve a problem.
An algorithm shouldn't include computer code. Instead, the algorithm should be written in such a way that it can be used in different programming languages.

Bibliography

Data Structure and Types
Why Learn Data Structures and Algorithms?
Introduction to Data Structures and Algorithms

Note: This Technical article was written as an assignment for Data Structures and Algorithms BootCamp held @DSEAfrica and @lux_academy. Thank you!