Programming Contests, Challenges and Online Judges

I can call myself a programmer, not the one who can stand & kick ass but yeah who can code & develop algorithms. I always wanted to improve on my skill set but never got the time to practice. Now I think I will be doing that forgotten thing whenever I have time. I came across a post on ThinkDigit forum where Sykora had listed some of the sites where one can test one’s capabilities. Tracing a little and I came across with a remake of that post. So I am sharing that list of sites with you.
There are different types of skill testing methods, here are the main three:

  • Contests are usually played out between participants in real time.
  • Challenges are mostly formats where you do the problem in your own time and submit the answer — your score will increase if your answer verified.
  • Online Judges are similar to challenges, but require you to submit the code itself, rather than the answer. The code will be run on the server, and you’ll be told if your program passed. Online Judges are usually more difficult than Challenges because the server imposes a time limit.

These are some of the challenges I’ve found the most interesting :

Project Euler

Languages : Anything

Project Euler is a collection of (mostly) mathematical problems that (in general) you’ll have to write some sort of program to solve. It’s a challenge (in the above sense of the word), so you have as much time as you want to solve the problems in any order using any language. It has the usual ranking system so you can compare yourself to everyone else, as well as within your country. New puzzles are added almost every week or so, but it can vary. The problems range from ridiculously easy, to impossibly hard. Each problem has its own forum thread, where people post how they solved it, with the code they used. However one can access the thread for a problem only if they’ve solved it.

Sphere Online Judge (SPOJ)

Languages : Lots. Check the site for the full list.

SPOJ is good because it combines problems from almost every other source. They’re not mathematical, just normal Computer Science problems. The 3 main limitations that they place on you are the running time, memory usage and code size. There are 1000s of problems, most of them are easy to solve in general, but hard to solve within the restraints imposed.

UVa Online Judge

Languages : C, C++, Java, Pascal

The same as structure as SPOJ, except you can only use those 4 languages. Whether or not you consider this a handicap, or simply a tougher rule set is your choice. It has lots of problems, some of them are duplicates of SPOJ (or may be it’s the other way around). In general, very challenging algorithmic problems.

The Python Challenge

Languages : It should be fairly obvious…

A dedicated challenge for python. As far as format goes, it’s the same as KlueLESS, but with some required knowledge of Python. For some levels you’ll need extra modules not provided with the standard distribution, but all of them are free downloads. This is possibly the best way to get interested in Python. There are 33 levels, and they get hard fairly quickly.

The Open Source Institute

Languages : Any

OSIX has a number of challenges, including the main “Geek Challenges” which are a series of problems one after the other. The problems are very interesting, but also get hard fairly quickly. Other problem types involve Bonus Levels, which are what you do when you get stuck on the main Geek Challenge. You can attempt these in any order. They also have reverse engineering challenges, and tests for various topics. The site is a bit buggy though (login issues).

Code Golf

The main focus of code golf is to solve the problem using the minimum number of keystrokes. The problems here are amazingly thought out, and the site in general is nice to read (no programming relevance, but it helps). You are ranked based on the number of bytes of your code, so the shorter the better. Solving these problems is by no means difficult. Coming anywhere near the top scores is insanely hard.


Languages : Any, for most challenges.

Hackits is new for me, and it’s very similar to OSIX. It has 6 challenge branches, including the main, logic and oktranon, which are logic challenges, crypt – a crypto challenge; script – a java script challenge; and misc, which doesn’t fit under any category. The difficulty varies, and there is a lot of non-programming work to do, before you actually find out exactly what you’re supposed to program.

My Thoughts

Finally I have find the perfect thing to do when you are free. I have joined Project Euler right away and will be peeking in for more. So what are you into?

Thanks to Sykora! [via]


One response to “Programming Contests, Challenges and Online Judges”

  1. ACM (Association for Computing Machinery) is also reported to be a similar site. I will check it and update it in the article if that is the case.