Learning JavaScript Data Structures and Algorithms

Table of Contents

Learning JavaScript Data Structures and Algorithms

Credits

About the Author

Acknowledgments

About the Reviewers

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Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Downloading the color images of this book

Errata

Piracy

Questions

1. JavaScript – A Quick Overview

Setting up the environment

The browser is enough

Using web servers (XAMPP)

It's all about JavaScript (Node.js)

JavaScript basics

Variables

Variable scope

Operators

Truthy and falsy

The equals operators (== and ===)

Control structures

Conditional statements

Loops

Functions

Object-oriented programming

Debugging and tools

Summary

2. Arrays

Why should we use arrays?

Creating and initializing arrays

Adding and removing elements

Two-dimensional and multi-dimensional arrays

References for JavaScript array methods

Joining multiple arrays

Iterator functions

Searching and sorting

Custom sorting

Sorting strings

Searching

Outputting the array into a string

Summary

3. Stacks

Creating a stack

The complete Stack class

Using the Stack class

Decimal to binary

Summary

4. Queues

Creating a queue

The complete Queue class

Using the Queue class

The priority queue

The circular queue – Hot Potato

Summary

5. Linked Lists

Creating a linked list

Appending elements to the end of the linked list

Removing elements from the linked list

Inserting an element at any position

Implementing other methods

The toString method

The indexOf method

The isEmpty, size, and getHead methods

Doubly linked lists

Inserting a new element at any position

Removing elements from any position

Circular linked lists

Summary

6. Sets

Creating a set

The has (value) method

The add method

The remove and clear methods

The size method

The values method

Using the Set class

Set operations

Set union

Set intersection

Set difference

Subset

Summary

7. Dictionaries and Hashes

Dictionaries

Creating a dictionary

The has and set methods

The remove method

The get and values methods

The clear, size, keys, and getItems methods

Using the Dictionary class

The hash table

Creating a hash table

Using the HashTable class

Hash table versus hash set

Handling collisions between hash tables

Separate chaining

The put method

The get method

The remove method

Linear probing

The put method

The get method

The remove method

Creating better hash functions

Summary

8. Trees

Trees terminology

Binary tree and binary search tree

Creating the BinarySearchTree class

Inserting a key in a tree

Tree traversal

In-order traversal

Pre-order traversal

Post-order traversal

Searching for values in a tree

Searching for minimum and maximum values

Searching for a specific value

Removing a node

Removing a leaf node

Removing a node with a left or right child

Removing a node with two children

More about binary trees

Summary

9. Graphs

Graph terminology

Directed and undirected graphs

Representing a graph

The adjacency matrix

The adjacency list

The incidence matrix

Creating the Graph class

Graph traversals

Breadth-first search (BFS)

Finding the shortest paths using BFS

Further studies on the shortest paths algorithms

Depth-first search (DFS)

Exploring the DFS algorithm

Topological sorting using DFS

Summary

10. Sorting and Searching Algorithms

Sorting algorithms

Bubble sort

Improved bubble sort

Selection sort

Insertion sort

Merge sort

Quick sort

The partition process

Quick sort in action

Searching algorithms

Sequential search

Binary search

Summary

Index

Learning JavaScript Data Structures and Algorithms

Learning JavaScript Data Structures and Algorithms

Copyright © 2014 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: October 2014

Production reference: 1201014

Published by Packt Publishing Ltd.

Livery Place

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Birmingham B3 2PB, UK.

ISBN 978-1-78355-487-4

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Credits

Author

Loiane Groner

Reviewers

Yaroslav Bigus

Maxwell Dayvson Da Silva

Vincent Lark

Vishal Rajpal

Commissioning Editor

Kunal Parikh

Acquisition Editor

Subho Gupta

Content Development Editor

Akashdeep Kundu

Technical Editors

Madhuri Das

Nikhil Potdukhe

Copy Editors

Maria Gould

Ameesha Green

Paul Hindle

Project Coordinator

Neha Thakur

Proofreaders

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Indexers

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Graphics

Ronak Dhruv

Valentina D'silva

Abhinash Sahu

Production Coordinator

Conidon Miranda

Cover Work

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About the Author

Loiane Groner lives in São Paulo, Brazil, and has over 8 years of software development experience. While at university, she demonstrated a great interest in IT. She worked as an assistant teacher for two and a half years teaching Algorithms, Data Structures, and Computing Theory. She represented her university at the ACM International Collegiate Programming Contest—Brazilian finals (South America regionals), and also worked as student delegate of the Brazilian Computing Society (SBC) for 2 years. She won a merit award in her senior year for being one of the top three students in the Computer Science department and graduated with honors.

She has previously worked at multinational companies such as IBM. Her areas of expertise include Java SE and Java EE as well as Sencha technologies (Ext JS and Sencha Touch). Nowadays, she works as a software development manager at a financial institution, where she manages overseas solutions. She also works as an independent Sencha consultant and coach.

Loiane is also the author of Ext JS 4 First Look, Mastering Ext JS, and Sencha Architect App Development, all published by Packt Publishing.

She is passionate about Sencha and Java, and is the Campinas Java Users Group (CampinasJUG) leader and Espirito Santo Java Users Group (ESJUG) coordinator, both Brazilian JUGs.

Loiane also contributes to the software development community through her blogs at http://loianegroner.com (English) and http://loiane.com (Brazilian Portuguese), where she writes about her IT career, Ext JS, Sencha Touch, PhoneGap, Spring Framework, and general development notes as well as publishing screencasts.

If you want to get in touch, you can find Loiane on Facebook (https://www.facebook.com/loianegroner) and Twitter (@loiane).

Acknowledgments

I would like to thank my parents for giving me education, guidance, and advice over all these years and for helping me to be a better human being and professional. A very special thanks to my husband, for being patient and supportive and giving me encouragement.

I would also like to thank my professors from FAESA, who taught me about the algorithms and data structures presented in this book.

Also, a big thanks to my friends and readers for all the support. It is really nice when people get in touch at conferences and by any social network mentioning that they have read one of my books and give me feedback. Thank you very much!

About the Reviewers

Yaroslav Bigus is an expert in building cross-platform web and mobile applications. He has over 5 years of experience in development and has worked for companies in Leeds and New York. He has been using the .NET Framework stack to develop backend systems; JavaScript, AngularJS, jQuery, and Underscore for the frontend; and Xamarin for mobile devices.

He is currently working for an Israeli start-up named yRuler (Tangiblee). Previously, he has reviewed Xamarin Mobile Application Development for iOS and iOS Development with Xamarin Cookbook, both by Packt Publishing.

I am thankful to my friends and family for their support and love.

Maxwell Dayvson Da Silva is a native Brazilian who works as a software architect for The New York Times. He has more than 11 years of experience working for two of Brazil's leading digital media companies. His work at Terra, a global digital media company, helped reach an audience of over 100 million people monthly with entertainment, sports, and news content. Later, he was part of Globo.com, the largest media conglomerate in Latin America. His contribution in the digital media field is only a portion of how he spends his time. Combining his passion for art and science, he creates games and interactive art installations. Inspired by his son, Arthur, he continually searches for new ways to spread science in a fun way to children both in NYC and Brazil. He can be reached at https://github.com/dayvson.

I would like to say thank you to Juliane Inês do Nascimento for taking care of Arthur in such an amazing way while I am away. 
You are an amazing mother!

Vincent Lark is an experienced programmer who has worked as a backend and frontend web developer for web start-ups in Luxembourg and France. He now focuses on creating modern web UIs and develops games as a hobby. He has also reviewed the book WebGL HOTSHOT, Packt Publishing.

Vishal Rajpal is an experienced software engineer who started developing professional software applications in 2011. He has worked primarily on Java, JavaScript, and multiplatform mobile application development platforms including PhoneGap and Titanium.

At present, he is pursuing his Master's degree in Computer Science from Northeastern University, Seattle, and has been working on Scheme (Lisp), Objective-C, computer systems, and algorithms.

He lives in Seattle and can be reached at <[email protected]>. You can also find out more about his work at https://github.com/vishalrajpal/ and https://www.vishal-rajpal.blogspot.com. He has also reviewed the book PhoneGap 3.x Mobile Application Development HOTSHOT, Packt Publishing.

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Preface

JavaScript is currently the most popular programming language. It is known as the Internet language due to the fact that Internet browsers understand JavaScript natively, without installing any plugins. JavaScript has grown so much that it is no longer just a frontend language; it is now also present on the server (Node.js) and database as well (MongoDB).

Understanding data structures is very important for any technology professional. Working as a developer means you have the ability to solve problems with the help of programming languages and data structures. They are an indispensable piece of the solutions we need to create to solve these problems. Choosing the wrong data structure can also impact the performance of the program we are writing. This is why it is important to get to know different data structures and how to apply them properly.

Algorithms play a major role in the art of Computer Science. There are so many ways of solving the same problem, and some approaches are better than others. That is why it is also very important to know the most famous algorithms.

Happy coding!

What this book covers

Chapter 1, JavaScript – A Quick Overview, covers the basics of JavaScript you need to know prior to learning about data structures and algorithms. It also covers setting up the development environment needed for this book.

Chapter 2, Arrays, explains how to use the most basic and most used data structure arrays. This chapter demonstrates how to declare, initialize, add, and remove elements from an array. It also covers how to use the native JavaScript array methods.

Chapter 3, Stacks, introduces the stack data structure, demonstrating how to create a stack and how to add and remove elements. It also demonstrates how to use stacks to solve some Computer Science problems.

Chapter 4, Queues, covers the queue data structure, demonstrating how to create a queue and add and remove elements. It also demonstrates how to use queues to solve some Computer Science problems and the major differences between queues and stacks.

Chapter 5, Linked Lists, explains how to create the linked list data structure from scratch using objects and the pointer concept. Besides covering how to declare, create, add, and remove elements, it also covers the various types of linked lists such as doubly linked lists and circular linked lists.

Chapter 6, Sets, introduces the set data structure and how it can be used to store non-repeated elements. It also explains the different types of set operations and how to implement and use them.

Chapter 7, Dictionaries and Hashes, explains the dictionary and hash data structures and the differences between them. This chapter covers how to declare, create, and use both data structures. It also explains how to handle collisions in hashes and techniques to create better hash functions.

Chapter 8, Trees, covers the tree data structure and its terminologies, focusing on binary search tree data as well as the methods trees use to search, traverse, add, and remove nodes. It also introduces the next steps you can take to delve deeper into the world of trees, covering what tree algorithms should be learned next.

Chapter 9, Graphs, introduces the amazing world of the graphs data structure and its application in real-world problems. This chapter covers the most common graph terminologies, the different ways of representing a graph, how to traverse graphs using the breadth-first search and depth-first search algorithms, and its applications.

Chapter 10, Sorting and Searching Algorithms, explores the most used sorting algorithms such as bubble sort (and its improved version), selection sort, insertion sort, merge sort, and quick sort. It also covers searching algorithms such as sequential and binary search.

Chapter 11, More About Algorithms, introduces some algorithm techniques and the famous big-O notation. It covers the recursion concept and some advanced algorithm techniques such as dynamic programming and greedy algorithms. This chapter introduces big-O notation and its concepts. Finally, it explains how to take your algorithm knowledge to the next level. This is an online chapter available on the Packt Publishing website. You can download it from https://www.packtpub.com/sites/default/files/downloads/4874OS_Chapter11_More_About_Algorithms.pdf.

Appendix, Big-O Cheat Sheet, lists the complexities of the algorithms (using big-O notation) implemented in this book. This is also an online chapter, which can be downloaded from https://www.packtpub.com/sites/default/files/downloads/4874OS_Appendix_Big_O_Cheat_Sheet.pdf.

What you need for this book

You can set up three different development environments for this book. You do not need to have all three environments; you can select one or give all of them a try!

For the first option, you need a browser. It is recommended to use one of the following browsers:

Chrome (https://www.google.com/chrome/browser/)

Firefox (https://www.mozilla.org/en-US/firefox/new/)

For the second option, you will need:

One of the browsers listed in the first option

A web server; if you do not have any web server installed in your computer, you can install XAMPP (https://www.apachefriends.org)

The third option is an environment 100 percent JavaScript! For this, you will need the following elements:

One of the