Programming Contests, Challenges and Online Judges

Revealed by sykora within programming on July 12th, 2008

I’m an ardent programmer, and I’ve always looked for places to test my abilities. I started looking for online portals to test programming skill, and after not much research, I found a number of sites, each testing a slightly different skills, in different ways.

There are different types of skill testing methods, here are the main three as I understand them :

Contests are played out between contestants 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 becuase the server imposes a time limit, and/or other restrictions on your code.

The following are my favorites…

Project Euler

Languages : Anything

My favorite up first. 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. There are currently 202 of them. Another thing I like about this one is that 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, 35 to be exact. And yes, you can submit in Brainf*ck. 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 ruleset 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 my favorite language. 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

I’ve always felt the name “Open Source Institute” was a bit misleading. Anyway, 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, it forgets I’m logged in and keeps asking me for my password and I never get anything done. But that’s probably my fault.

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.

Hackits

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 jacascript 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 experiences with this site have been buggy, so I haven’t really gone deep here. Pity, actually.

Apart from these, there are a number of periodic contests I try to keep in touch with :

BitWise - IIT Kharagpur’s annual programming contest. Problems are very challenging, algorithmic

There are probably a number of other online programming outlets, for programmers of all calibers. If you know of one I don’t, by all means mention it to me, I want to know.

– This is a mild rework of a post I made here.

Tags: programming