Category: CodeFights News

Get all the latest CodeFights announcements! Check here for information about product launches, updates, contests, and giveaways. Plus get all the details of what’s going on here at CodeFights HQ in San Francisco!

CodeFights is the most fun way to practice your programming skills. Master new languages, prepare for interviews, and much more! Join an active community of 500,000+ engineers!

Can Learning Be Addictive?

Can Learning Be Addictive?

CodeFights CEO Tigran Sloyan gave a TEDx talk in October, and we’re so excited to be able to share it with the world!

Watch the video to discover how advances in neuroscience, psychology, and game theory have paved the way for the creation of addictive learning systems like CodeFights.

Tigran outlines the basics of an unconventional – but proven – method of creating geniuses. If you start teaching a young child one skill very early on, and keep them focused on that single skill for years, they will excel at it. He discusses how following a similar practice in his childhood led to him becoming an international math champion.

His experiences led him to discover the core idea of CodeFights: that practicing a skill needs to be fun in order to be effective! He talks about why the challenge-achievement-dopamine loop (a core component of CodeFights gameplay) is critical to keeping people engaged in any process.

Challenge Achievement Dopamine Loop

Tell us…

Have you ever experienced the challenge-achievement-dopamine loop that Tigran talks about? If so, has it helped you to learn a new skill – coding or otherwise? Let us know on the Forum over on CodeFights!

The CodeFights Polyglot Marathon

The CodeFights Polyglot Marathon

Polyglot (noun):

A person who has mastered multiple languages.

Are you a programming polyglot? Here’s your chance to prove it!

If you pride yourself on knowing multiple programming languages, then you’re going to love our next worldwide coding tournament. On November 11, CodeFights is hosting the Polyglot Marathon.

This marathon is composed of twelve coding tasks. You get to choose which language you want to solve each question in, and each one must be solved in a different coding language. If that sounds tricky, that’s because it is! You have to know 12 different programming languages well enough to solve a coding task in them. (That’s why it’s really helpful to have our new Syntax Tips feature displayed in each challenge. 😁)

Consider this your chance to practice programming in all of those different languages that you love but don’t get a chance to use very often. Keep in mind that while CodeFights does support 38 different programming languages, Python 2 and Python 3 will count as the same language for the purposes of this marathon, as will C and C++.

The Polyglot Marathon will start Saturday, November 11 at 9:00 AM PST. Remember to adjust this to your own time zone when you’re planning out your day! Since this is going to be a difficult marathon, you’ll have two hours to solve all of the tasks.

The top 10 participants will all receive a $50 Amazon gift card and 500,000 CodeFights coins. Will you be one of them?

Sign up on CodeFights!

Polyglot Marathon Rules:

  • You must solve each task in this Marathon using a different programming language.
  • You can run your code as much as you want before submitting, which will run it against sample test cases only. When you actually submit your solution, we run all the tests on it.
  • Your score depends on how many tests your program passes. If you pass all the tests, you get the maximum possible score for that task. Passing sample tests does not give you points, so you need to pass some of the non-sample tests to get a positive score.
  • In the case of a tied score for a task, the participant with the lowest time penalty is ranked highest.
Hello World! Introducing Language Syntax Tips

Hello World! Introducing Language Syntax Tips

Ever wondered how to say Hello world in 38 different programming languages? CodeFights has you covered!

We just launched Syntax Tips, a brand-new feature in all of our coding tasks and challenges that gives you important information about how to format code in every programming language that our platform supports.

It can be hard to remember how to format a function, write a comment, print to the console, or return output in a specific language. This is especially true if you’re just learning the language, or if it’s one that you don’t use very frequently. So this is going to come in very handy!

Hello world

Gif of all supported programming languages on CodeFights
Hello world in 38 languages!

Think of Syntax Tips as your own personal Rosetta Stone for programming languages. To see tips for a particular language, just choose that language from the dropdown menu at the top right side of the code editor. (This is also how you change the language that you’re writing in to solve a task.)

Hello world in JavaScript

You do not need to do anything different to access Syntax Tips. This section is now at the bottom of every coding task’s description section, no matter which CodeFights mode you’re using.

Just as a reminder, CodeFights now supports 38 different programming languages: ClojureCoffeeScript, Common Lisp, C, C++, C#, D, Dart, Elixir, Erlang, Free Pascal, Fortran, F#GoGroovyHaskellJavaJavaScript / ES6JuliaKotlinLuaNimObjective-COCamlGNU OctavePerlPHPPython 2Python 3RRubyRustScalaSmalltalkSwift 3TclTypeScript, and Visual Basic.

If your favorite language isn’t on this list yet, don’t worry. Because we know how important it is for you to be able to practice programming in the language of your choice, we add new language support to CodeFights all the time. (Seems like just yesterday that we only had 14 languages, and look at us now!)

Tell us…

What you you think of Syntax Tips? Let us know over on the CodeFights user forum!

Beautiful JavaScript Winner Code Walkthrough

Beautiful JavaScript Winner Code Walkthrough

“It’s rewarding. It feels good to come up with a solution, and just to in general practice how you approach solving problems.”

– Beautiful JavaScript winner boomx on CodeFights

The CodeFights Beautiful JavaScript contest wrapped up a few weeks ago, and the winners were CodeFighters boomx, arnav_a2, and marcusekeenan. Each of them won a trip to San Francisco and three nights at a hotel downtown. We recently had the first of our winners visit us!

boomx is a software developer in North Carolina. Earlier this year, he went to a conference where a presenter talked about how important it is for programmers to stay sharp by practicing outside of work. One of boomx’s coworkers mentioned that CodeFights is his favorite site for practicing programming, so he signed up to try it too. boomx solved a few challenges here and there, but really got into the site once he saw the Beautiful JavaScript challenge. Now he tries to solve the daily Challenge as often as he can to keep his skills sharp!

We had a great time hosting him at CodeFights HQ. Our Engineering team really enjoyed getting to talk with him about his solution, coding in general, and of course JavaScript!

Beautiful JavaScript Winner boomx
Oh, you know, just casually pointing at a contest winner.

During his visit, he was kind enough to give us a great walkthrough of his solution. He started by talking about his original naive solution, and then about how he optimized it. It’s really interesting to see the code’s evolution from its (still great!) beginnings to the expressive, readable, and concise solution that you can see at solution #191. Watch his explanation below!

Thanks, boomx!

We’ll post the next two solutions when our other winners visit us later this year, so stay tuned!

Beautiful JavaScript Contest Winners

Beautiful JavaScript Contest Winners

The Beautiful JavaScript contest was an amazing event. We got over 500 solutions from our awesome CodeFighter community! It ended up being really hard to narrow our list of favorites down to just three. But after a lot of thought, our judges have chosen the three that they think are the most expressive, readable, and concise – in other words, the most beautiful – as our winners.

The winners

Congratulations to the winners of the Beautiful JavaScript contest! Each of these CodeFighters has won a three-day trip to San Francisco, and will get to come nerd out with us about JavaScript at CodeFights HQ.

See the winner’s solutions section of this post for their full solutions to the challenge secretArchivesLock! We’re going to be posting an in-depth explanation of each winner’s solution, in the winner’s own words, so stay tuned for that in the next few weeks.

Honorable mentions

We also want to acknowledge the following CodeFighters with an honorable mention and a CodeFights gift box!

  • ben_s24: This CodeFighter’s solution was a crowd favorite – commenters on the challenge really liked his solution!
  • hydralisk: Not only did this CodeFighter have a great solution to the challenge, he also reviewed all of the solutions to compile his own list of favorites.
  • jeff_b36: This CodeFighter created an awesome website to help visualize the challenge.

The winner’s solutions

And now the moment you’ve all been waiting for – the winner’s solutions!

arnav_a2’s solution

arnav_a2's Beautiful Javascript Solution

boomx’s solution

boomx's Beautiful JavaScript Solution

marcusekeenan’s solution

marcusekeenan's Beautiful JavaScript Solution

Congratulations to our winners! And everyone who submitted a solution, great work! We really enjoyed reading through all of the creative solutions that you all came up with.

Tell us…

Did you have a favorite solution that didn’t end up being a winner or an honorable mention? Let us know over on the CodeFights Forum!

Introducing the CodeFights Arcade Database World

Introducing the CodeFights Arcade Database World

The ability to access, understand, and manipulate data is extremely important in the current engineering job market. Employers are increasingly listing SQL as a “required skill” in job listings, whether the job is a back-end engineering job or not.

Data scientists, data analysts, researchers, and many others also need to be able to access information that’s stored in relational databases. No matter what your job title is, the ability to dive deep into an organized collection of data to answer questions, uncover patterns, and discover information is incredibly useful!

But unless you already work with a relational database, whether at a job or at school, how do you practice writing efficient and accurate queries?

Database World

At CodeFights, we wanted to give people a fun, easy way to practice writing queries and manipulating data. That’s why we created Database World, our latest addition to the CodeFights Arcade!

Database World has over 80+ tasks spread out over 16 levels. The questions start out easy… But they ramp up in difficulty as you progress. This means you’ll never get bored as you practice!

Database World is a unique way of learning database skills that’s both educational and entertaining. While you write more and more queries, you’ll start to know what to look for and how to pinpoint the information you need. You’ll get faster and have less hesitation. In other words, writing amazing SQL queries will become second nature for you. You’re going to be able to leverage this into being highly competitive in the job market!

Back up – what’s the Arcade?

There are five different worlds in the CodeFights Arcade. Each world has tons of levels and tasks to complete that help you master a particular concept.

  • Start tackling tasks and get familiar with Arcade in the The Intro.
  • Get up to speed on programming fundamentals in The Core.
  • Python World focuses on helping you master programming in Python.
  • Solve graph theory questions in Graphs World.
  • And now, practice your SQL and database skills with Database World!

Get started!

Are you ready to become a database guru? If so, get started on Database World with projectList, the first task in the introductory level!


Interview Practice: Graphs, Advanced Trees & RegEx

Interview Practice: Graphs, Advanced Trees & RegEx

We’ve just added three-brand new computer science topics to Interview Practice! Get ready to dive deep on Graphs, Trees: Advanced, and RegEx. We’ve added these topics to our Extra Credit learning plan, which covers all of the topics in Interview Practice. 

Why are these topics so important to know for technical interviews? Read on for a brief introduction to each concept!


Graphs Interview Practice TopicA graph is an abstract data structure composed of nodes and the edges between nodes. Graphs are a useful way of demonstrating the relationship between different objects. For instance, did you know that you can represent social networks as graphs? Or that the 6 Degrees of Kevin Bacon game can be modeled as a graph problem? Graph questions are really common in technical interviews. In some cases, the question will be explicitly about graphs, but in other cases the connection is more subtle. Read our tutorial to get up to speed on this topic and to learn how to identify this kind of question. Then practice your skills on graph questions from real technical interviews!

Trees: Advanced

Trees: Advanced Interview Practice TopicA tree is a data structure composed of parent and child nodes. Each node contains a value and a list of references to its child nodes. Tree traversal and tree implementation problems come up a lot in technical interviews. Common use-cases for an interview are: needing to store and do searches on data that is sorted in some way; needing to manage objects that are grouped by an attribute (think computer file systems); or implementing a search strategy like backtracking. You need to be very familiar with how to deal with these kinds of questions! (The tasks in Trees: Advanced ramp up in difficulty from the ones you get in the Trees: Basic category, so make sure you finish those questions before moving on to these ones!)


RegEx Interview Practice TopicA regex is a string that encodes a pattern to be searched for (and perhaps replaced). They let you find patterns of text, validate data inputs, and do text replacement operations. A well-written regex can make it easier to solve really tricky interview questions like “Find all of the 10-digit phone numbers in a block of text, where the area code might or might not be surrounded by parentheses and there might or might not be either a space or a dash between the first and second number groupings”. While the specifics of how to implement a regex can vary between languages, the basics are pretty much the same. In the topic tutorial, we cover regex character classes, quantifiers, anchors, and modifiers and how to use them to write a good regex.    

Start now

These topics might not get asked in every interview, but they’re important to know! Read the tutorials about each concept, then solve the real interview tasks to practice your skills and solidify your understanding of the topic. (Learn more about how we’ve updated the Interview Practice experience to make it an even better practice and preparation tool.)

If you’re signed up for the Extra Credit learning plan, these topics have been added to your Interview Practice page already. If you’re signed up for a different learning plan, you can switch over to Extra Credit. Or you can sign up for a customizable Freestyle plan and add these topics!

New supported languages: C, Erlang, Rust, and more!

New supported languages: C, Erlang, Rust, and more!

You asked, and we listened! Over the past few weeks, we’ve added support for 14 more programming languages to the CodeFights platform.

The new languages on CodeFights are:

  • C
  • Clojure
  • CoffeeScript
  • Common Lisp
  • D
  • Elixir
  • Erlang
  • Julia
  • Kotlin
  • Lua
  • Nim
  • Objective-C
  • OCaml
  • Rust

With these additions, we now support 32 coding languages that you can use to solve CodeFights tasks! Being able to select your language of choice means that you can master your primary coding language, practice a language that you’re in the process of learning, or just try one on for size.

See the postscript to this blog post for the entire list of languages that you can use on the platform. Keep in mind that you can’t use some languages to solve some tasks, so if that’s the case you may need to choose a backup language. (For instance, you can’t use Lua to solve a database task, so you’ll need to switch to MySQL.)

We hope that you’ve found a few languages that you’re excited about using! If your preferred language isn’t on our list, you can start a post on the CodeFights Forum to request it. We try to add new supported languages a few times a year based on user requests and language popularity.

Programming Languages Supported on CodeFights

CodeFights Supported Languages

The languages that our platform currently supports are:

Bash, Clojure, CoffeeScript, Common Lisp, C, C++, C#, D, Elixir, Erlang, F#, Go, Haskell, Java, JavaScript (ES6), Julia, Kotlin, Lua, MySQL, Nim, Objective-C, OCaml, Perl, PHP, Python2, Python3, R, Ruby, Rust, Scala, Swift3, and Visual Basic.

Join the Beautiful JavaScript Challenge!

Join the Beautiful JavaScript Challenge!

Check out the Beautiful JavaScript challenge on CodeFights! You must submit your solution by noon on July 26. See the Official Rules at the end of this post for more details.

At CodeFights, we heart JavaScript. A lot. In fact, we love it so much that our whole stack, front-end and back-end, is JavaScript. Node + React + Meteor FTW!

We know we’re not the only ones who feel this way, and we want to share the JavaScript love. That’s why we’re launching our first-ever Beautiful JavaScript challenge today!

Think of this challenge as a beauty pageant for code. Write your solution in the most elegant JavaScript you can, polish it up, then click Submit. Our panel of judges, the senior engineers here at CodeFights, will be looking for code that’s expressive, readable, and concise. They’re going to choose the three most beautiful solutions to this challenge as the winners!

If you win, you’ll receive an all-inclusive trip to San Francisco, including a round-trip ticket from any city in the U.S. and three nights at a hotel downtown. And of course you’ll get to come hang out with us at CodeFights HQ and nerd out about all things JavaScript and CodeFights!

Excited yet? Yeah, so are we! We can’t wait to see the great solutions that you come up with. Join the Beautiful JavaScript challenge on CodeFights!

Official rules for Beautiful JavaScript:

  • All CodeFighters can solve this challenge, but only people in the U.S. are eligible to win.
  • You must write your solution in JavaScript, obviously!
  • Your solution must be submitted before the contest closes at 12:00 PM Pacific Time on Wednesday, July 26.
  • The three winners will be notified by email and their names will be posted on the CodeFights forum by 5:00 PM Pacific Time on Friday, July 28.
Ace Your Next Interview With CodeFights

Ace Your Next Interview With CodeFights

You know that you need to prepare for technical interviews – right? Of course you do! Companies rely on technical interviews to weed out people who can’t cut it. And for qualified candidates, they’re used to gauge aptitude, interest, and intelligence. So the stakes are really high, and you need to do everything you can to give yourself a competitive edge.

But it can be hard to know what exactly to study. There’s so much information out there, and sometimes it feels like you have to know everything. If you start studying without a plan, you risk wasting your time by preparing for the wrong sorts of questions, not studying enough, or any other issue that might hamper your ability to knock the interviewer’s socks off. And we want those interviewer’s socks to be knocked all the way off! In other words, we want to make sure that you ace your next technical interview.

That’s why we’ve made some changes to Interview Practice that make it an even better interview prep tool. Now you can join a study plan that gives you a timeline and a way to track your progress (or you can create your own plan). Each study plan has essential topic overviews and real interview questions from real companies. This makes it easy to know what topics to cover and how much to study.

Choose a study plan

Each study plan covers the most commonly-asked interview topics that you should prepare for, given the amount of time before your interview.

  • Crash Course: As the name implies, the Crash Course is perfect for when you have a technical interview coming up soon! This study plan will get you up to speed on computer science fundamentals. These are common topics that you must know in order to do well on interviews. Choose this plan if you have two weeks (or less) to prepare for an interview.
  • Fundamentals: If you have an interview coming up in the next 2-6 weeks, this is the perfect study plan for you. Since you’ve got a little more time to prepare, the Fundamentals plan covers some other common topics like bits, strings, sorting algorithms, and useful problem-solving techniques.
  • Extra Credit: If you plan to start interviewing at some point in the future, but don’t have any specific plans yet, check out the Extra Credit study plan. Extra Credit covers big topics like number theory, counting, and geometry. These concepts are really important but don’t get asked as often in interviews.
  • Freestyle: If none of these options is exactly what you need, don’t worry. It’s quick and easy to create a Freestyle plan! Just select the topics that you need to study and the amount of time you have before your interview, and our system will create a customized study plan for you to follow.

Once you’ve chosen a study plan, Interview Practice keeps you on track by recommending a minimum number of coding tasks to solve each day – and reminding you to start hustling if you’re not meeting your daily quota!

Study important concepts

A mainstay of the technical interview process is asking questions that help the interviewer determine how well you understand computer science fundamentals like data structures and algorithms. The interviewer is also assessing whether you can implement these concepts appropriately, and whether you take time and space complexity into account. Depending on where you are in your career, some of these topics might be ones that you haven’t touched since you were in school. Or maybe you’ve never formally studied them.

Interview Practice gives you a refresher course on these common interview topics. You need to be strong on these in order to do well in technical interviews, whether you’re a junior developer or have been in the field for years.

Study important interview concepts.

Solve actual coding problems

The questions you get asked in technical interviews are aimed at making sure that you have a fundamental understanding of how to write code. The interviewer also wants to make sure that you take edge cases and optimization into account. While you’re whiteboarding, interviewers are also gauging how you think while you’re working through a problem.

Actually writing code that solves the actual technical interview questions makes you more comfortable with the process. We can’t emphasize this enough. The absolute best way to ensure that you’re good at interviewing is to practice solving coding interview problems!

Each topic in Interview Practice has real interview questions from real companies for you to practice on, ordered by difficulty. As you solve them, you’re solidifying your knowledge of the topic and becoming familiar with this kind of problem.

Get going!

Interview Practice gives you a plan and helps you stick to it. This eliminates the guesswork about what you need to study,  how much you needs to study, and how you should organize your time. Work your way through each topic, reviewing each concept in the overview and solving the questions. As you practice, you’re becoming a better programmer. You’re also giving yourself a serious advantage in technical interviews!

Time to get started! Head to CodeFights and get started on the new and improved Interview Practice today.