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December 10, 2015

35+ coding challenges to get your teeth into

We’ve seen a couple of seasonal coding challenges being thrown around recently, so we thought we’d take the chance to compile a list of our recent favorites. There are plenty of general challenges here, so regardless of the time of year or your preferred language, you’ll be able to find something to get your teeth into.

We’ve seen a couple of seasonal coding challenges being thrown around recently, so we thought we’d take the chance to compile a list of our recent favorites. There are plenty of general challenges here, so regardless of the time of year or your preferred language, you’ll be able to find something to get your teeth into.


24 Pull Requests

In their own words

’24 Pull Requests is a little project to promote open source collaboration during December. The idea is basically “Send 24 pull requests between December 1st and December 24th”, encouraging developers to give back to open source with little gifts of code throughout December.’


Advent of code

In their own words

‘Advent of Code is a series of small programming puzzles for a variety of skill levels. They are self-contained and are just as appropriate for an expert who wants to stay sharp as they are for a beginner who is just learning to code. Each puzzle calls upon different skills and has two parts that build on a theme.’



HackerEarth has a big range of timed programming challenges that cover everything from game development to the internet of things. If you’re looking for hiring challenges or language-specific tests, this is the place to go.



Coderbyte cleverly combines programming challenges and interview questions in order to help you prepare for jobs. If you don’t need the recruitment side of it, you can still access a big range of coding conundrums to test your skills.



In their own words

‘The HackerRank team is on a mission to flatten the world by restructuring the DNA of every company on the planet. We rank programmers based on their coding skills, helping companies source great programmers and reduce the time to hire.

As a result, we are revolutionizing the way companies discover and evaluate talented engineers. The HackerRank platform is the destination for the best engineers to hone their skills and companies to find top engineers.’


Project Euler

In their own words

‘Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.’



Codility offers both lessons and challenges, so if you’re not too confident you can follow the series of guides before starting in on the challenges. As it’s used by recruiters, Codility gives you a practical grounding in potential interview questions and tests too.



Programmr offers a huge range of challenges organized by language and type. You can even challenge your friends to participate. Unlike a lot of other websites in this list, they even have an API so you can really make it your own.



In their own words

‘Topcoder gathers the world’s experts in design, development and data science to work on interesting and challenging problems. Members are provided with opportunities to demonstrate their expertise, improve their skills, and win cash, while helping real world organizations solve real world problems.’


Daily Programmer (Reddit)

Take part in a new challenge every day, or submit your own and have it rated and tested by the community. It’s a great option if you like to discuss decisions with others rather than just working solo.


Programming Challenges (Reddit)

Another great subreddit for programmers. Challenges aren’t posted daily, but they are posted often, generally language agnostic and offer plenty of scope for friendly debate.



In their own words

‘Codewars is a collective effort by its users. They are creators – authoring kata to teach various techniques, solving kata with solutions that enlighten others, and commenting with constructive feedback. The leaders among them moderate the content and community.’


Spoj (Sphere Online Judge)

Users submit challenges which are automatically assessed before reaching the community. As well as supporting over 45 languages, Sphere Online Judge also boasts an intuitive browser-based content management for easy contest creation.


Code Chef

In their own words

‘CodeChef is a global programming community. We host contests, training and events for programmers around the world. Our goal is to provide a platform for programmers everywhere to meet, compete, and have fun.’


Seven silly programming challenges to do for fun

‘Practice makes perfect. Unfortunately, the more we do something, the more set in our ways we risk becoming. The more we solve the same sort of problem using the same tools, the better we get at it – but at the expense of more flexible thinking’ says Nancy Deschenes, creator of a series of puzzles to challenge your skills and lead you to think in different ways.


Five programming problems every software engineer should be able to solve in less than an hour

In their own words

‘The following problems are ridiculously simple, but you’d be surprise to discover how many people struggle with them. To the point of not getting anything done at all. Seriously.’



In their own words

‘CodeEval is a platform used by developers to showcase their skills. Developers can participate in app building competitions and win cash/prizes. They can also solve programming challenges as a way to impress employers with their technical skills. Employers can use CodeEval as a way to enhance their brand by launching competitions/programming challenges and as a means to get introduced to the best developers.’



In their own words

‘DEVDRAFT connects ambitious software developers to a broad range of tech companies through code challenges that expose incredibly deep qualification metrics. Our belief is that given high merit scores talented people can get connected to the right opportunities quicker than if they went through a traditional route.’



Lots of live contests, gyms, groups and problems to get your teeth into, plus an API.



In their own words

  • Deliberately focus on improving your skills.
  • Gain a deep understanding of the fundamentals of your craft.
  • Experiment in a place where bugs don’t inconvenience anyone.
  • Practice providing useful critique.
  • Discuss code in both subjective and objective terms.
  • Strengthen your problem-solving skills by guiding others through the process.



In their own words

‘At CodinGame, we believe that everyone should be able to discover the pleasure of coding. We are programmers at heart, and we know that code is a powerful tool to innovate and create. It’s a matter of passion, but above all, it’s fun. So we’ve imagined a platform which merges programming and video games. Our goal is to help developers from around the world, whatever their qualifications or professional experience, to learn, improve their coding skills and find their dream job, while playing.’



A series of quizzes, exercises and problem-solving challenges in a more serious format.



Checkio is a game in challenge form. Visually it’s a world apart from standard programming challenges, but it still keeps the traditions of leaderboards, community discussion, and problem-solving.


Empire of Code

In their own words

‘Empire of Code is a space game with a mix of strategy, tactics and coding.
You can play the game with or without coding skills, but knowing how to code will definitely give you an advantage.’


What’s the best coding challenge you’ve ever done? Tell us about it on Twitter.

Scheduling everything for everyone

Cronofy reviews sourced by G2