Big O notation, or its counterpart Big Theta, are mathematical notations used in computer science to describe the performance or complexity of a particular algorithm. Big O is also used to describe the execution time required or the space required to store an algorithm.
Software engineers use programming to solve real-world problems. To ensure they’re applying the most effective solution or algorithm, engineers use big O notation to test and compare them for complexity and efficiency. Much like in cooking, there are a million different ways to cook one dish, but there’s one that’s the best, and big O notation helps you find the best one.
Knowing big O basics is essential if you aspire to become a senior dev, and it’ll help you write faster code and improve your codebases. You can even expect to be asked situational big O questions on the spot during interviews as you’ll need to know which big O algorithm works best off the top of your head!
Whether you’re looking to study a programming language or become a back-end developer, this article can help you. Keep reading as we explore the best courses on big O algorithms and cover their syllabus, strengths, and course structure. We’ll also provide some amazing free resources for you at the end of our best big O course ranking.
Learn Big O Notation: The Best Way
Because knowing big O notation is a skill needed for many jobs, the best big O online courses include interactive and practical experience — coding and completing lesson tasks that mirror real-life situations. Learning by doing is the best way to see how the notation works and get a full understanding of its functions.
It’s also beneficial to find a course or site that covers both big O notation algorithms and data structures. You need to know how to build data structures and as well as understand complexity to fully work with big O notation.
However, if you’re just looking for a refresher or one or the other, we have courses here for you too!
1. Qvault – Best Big O Notation Courses
What makes it the best big o course:
- Learn by doing — you’ll learn big O notation through interactive challenges and multiple choice questions
- Deep learning — Qvault have two entire courses dedicated to teaching the ins and outs of big O data structures and big O algorithms.
- Some may prefer lectures over interactive lessons
So many self-taught developers, and some who are taught through more traditional means, ace the computer science basics but lack the extra knowledge they need to ascend to senior developer positions.
To help you get there, Qvault offers two big O courses:
Both are designed exactly to bridge that gap to becoming a senior dev by teaching you how algorithmic complexity works, having you code your own algorithms interactively as well as answering multiple choice questions.
Their first big O online course, Big O Algorithms, starts with standard big O analysis and complexity, before you move on to coding sorting algorithms to determine their big O complexity. After this, you move on to complexity theory.
Some coding experience is necessary — and math skill will help — and Qvault’s Big O Algorithms course is written in Go, so if you haven’t tackled Go (Golang) before, we recommend you take Qvault’s excellent and industry-leading Go Mastery courses first — you get access to all their courses for a fixed $6 per month.
See also: our ranking of the best Golang courses.
Once you’ve completed their first online big O notation coding course, you move on to Big O Data Structures, teaching complex data storage and common data structures, directly interacting with structures like linked lists, stacks and queues, and tougher big O structures like trees, hashmaps and graphs. It’s built in Python, one of the most common languages which you’ll probably already have some experience with.
Some elements of the big O courses are technical, but massively rewarding. These kinds of data structures and algorithms skills really do separate accomplished junior devs from their senior dev colleagues. And, with full access to Qvault’s entire course range starting at just $6 per month, it’s a fantastic deal to learn such valuable computer science skills.
You’ll not only get acquainted with these data structures and algorithms, but directly code and interact with them, as well as fine-tuning your Go and Python skills. Overall, these are two of the best big O Notation courses online.
2. Coursera – Good Lectures To Learn Big O
- University accredited programs
- Taught by computer science professors
- Lecture-based courses
Coursera is your one-stop-shop for university online classes, without the stress of going to university.
Coursera’s Data Structures and Algorithms Specialization, by the University of California San Diego and HSE University, is a four-part program that helps programmers master algorithmic programming techniques.
Coursera’s courses include:
- Course One: Algorithmic Toolbox
- Course Two: Data Structures
- Course Three: Algorithms on Graphs
- Course Four: Algorithms on Strings
It’s during week two of course one that you learn about big O notation. It involves a 6-minute video and a set of practice questions.
There is the option to only take the Algorithmic Toolbox course, but to take full advantage of the algorithm and data structure curriculum, the whole program is recommended.
You can start the course at any time and it’s free to enroll. You can also pay for a certification, which gives you access to graded assignments and a certificate. It takes approximately 8 months to complete the entire program with 6 hours of study a week. You can also set your own deadlines and work at a pace best for you.
There are two projects for the whole program, but aside from that, it’s entirely lecture-based. It does require the knowledge of at least one programming language, so it’s better for intermediate students than beginners.
Once you’ve completed the program, you should feel comfortable applying basic algorithmic techniques and data structures and be able to use these to solve real-world problems.
This program is best suited for those that prefer lecture-based learning and want to invest in a long-term program, though for a technical subject we recommend committing to an interactive big O course.
Other Coursera specializations include:
- Algorithms Specialization by Stanford University
3. Udemy – Big O Notation Crash Course
- Fast and efficient course
- The website often has sales on courses
- Not as thorough as other courses
Udemy is a place where individuals and companies unite to host their online courses, and people like us can take them without breaking the bank.
While there’s stiff competition on the site, we think the best choice is the Complete Algorithms Complexity and Big O Notation Course by Cronis Academy. This is a crash course on algorithm complexity, with a focus on big O notation, that aims to take beginners to experts in just two hours.
Ideal for beginners, it introduces users to the mathematics behind the algorithms and the different types of complexities, like recursion, strings, and space complexity. It does require basic programming knowledge to understand, but people love this course for its digestible delivery of complex evaluation and big O notation.
There is no hands-on practice calculating complexity, or any focus on building data structures, so those looking to get into developing or gain experience are better suited for the Qvault course. But, along with being a nice introduction to big O concepts, it also makes an excellent refresher course for any developers out there.
The site does offer other big O notations courses, but this is the only one that specifically focused on it, making it the perfect choice.
With Udemy, you buy each course individually instead of subscribing to the site. Currently, this course is $59, but the site often runs amazing sales, so it’s worth waiting it out to snag a good deal!
4. LinkedIn – Learn Big O Notation in Java
- The convenience of a familiar site
- A course you can build off of
- No practical experience using big O notation
LinkedIn is a favorite amongst professionals for its networking capabilities, and now they love it for its online learning.
The Introduction to Data Structures & Algorithms in Java is an intermediate-level course that explores how to use Java to write commonly used data structures and algorithms. On top of big O notation, you’ll learn how to analyze Euclid’s and Bubble’s algorithms, how to calculate complexities, and how to implement stacks, queues, and recursion.
Because it focuses on Java, the course provides greater language-specific detail, unlike other generalized courses that apply to all languages.
The course is shy of 5 hours long and consists of 10 chapters, each containing multiple lessons. At the end of each chapter, there’s a quiz you must complete and pass. Once finished, you’ll earn a LinkedIn verified certificate that goes on your profile for your professional network to see.
There’s plenty of courses to carry you on once you’ve completed this, so you can build on what you’ve learned. You get unlimited access to all the courses with LinkedIn Premium, which starts at $25.00 per month, after the free trial.
5. Codecademy – Big O Notation Interview Prep
- You can try the course for free
- Covers other asymptotic notations
- Strictly lecture-based
Codecademy is a computer science online educational site that focuses on teaching a variety of languages, as well as other career-based courses, like web design and full-stack development.
Instead of offering a big O notation course, it offers an Asymptotic Notation lesson, which has a section on big O notation in it. This is because Big-O is an asymptotic notation. Along with learning about big O, you’ll learn about Big Theta and Big Omega notations, and runtimes.
You do have to pay for the pro subscription to get access to this course. Because of this, it’s only a viable option for those looking to invest, and would benefit from the whole interview prep course, as it costs upwards of $199 a year for the pro subscription.
Free Big O Notation Resources: Learn Big O For Free
Qvault is the only online learning site that truly encapsulates big O notation, offering both an algorithm and data structure course, but there are some amazing free resources you can use to help you along, no matter which course you take.
First, we have Khan Academy. This site doesn’t need an introduction, as it has helped thousands of students of various ages get access to world-class learning support.
They offer a free “course” and practice on asymptotic notation. We say “course” because it’s more of a series of articles like you’d see in a textbook describing the functions and how to use notations. Then at the end, there are practice multiple-choice questions.
Overall, it’s a nice and easy free course you can use after, or alongside, one of the courses above to get extra practice learning big O notation.
Next, we have the Big-O Cheatsheet. This one is self-explanatory. It’s essentially a webpage that has a range of graphs and charts that indicate what are the best and worst case complexities for search and sorting algorithms.
It was created by a dev who was tired of scrambling to search for answers before a technical interview (we told you it was common), so he created a big cheat sheet online for everyone to enjoy. This is an absolute must, for anyone planning to work with Big-O notation.
Big-O quiz focuses only on big O notation and even has its own big O cheat sheet. Brilliant offers practice and courses on all things math and science, so it’s a worthy site to have in the bank as it can help you with other topics!