Where Hackers Eat Crackers.

14 001 831 submissions, 321 473 registered users, 5 413 public problems


We present the long-awaited new, fresh, and crispy design of SPOJ! It's taken us a while to get here since 2004, but hey, it looks good - doesn't it? There's now a new feature for tagging and grading problems. We are also working to make SPOJ as mobile-friendly as possible. Stay tuned, because there are many more surprises to come!

Goodbye Pyramid

During the last six months, we have been gradually migrating our "checkers" (servers which execute submissions) from old to new machines. The procedure required some care since the new machines have significantly greater processing power. The main difficulty was adjusting the time limits for problems: in general, the new machines seemed to be more "tolerant" of slow solutions than the old ones. Over the 10 years of existence of SPOJ, our great community has produced over 13.5 million submissions (10 million of which on the old checkers) and we didn't want to rejudge all of them. So, we designed an algorithm for recalculating submission running times by interpolation. Data for reliable interpolation came from a real rejudge of a representative sample of 5% of the submissions, i.e., 511,000 submissions have been rejudged over the past six months. At the end, we changed the time limits of test cases keeping them in relation to running times of solutions.

read more

Lambda Days 2015 Challange

For the second year in a row Lambda Days come to Kraków to bring together people passionate about functional programming. The tickets are out and the only way to attend at the moment is to get high score in their special programming contest. If you are interested in participation visit http://lambdadays.sphere-contest.com.

Banning cheaters

We have intensified banning cheaters (users who copy codes from the internet and submit them here). Soon all of them from "Cheaters" thread on forum will be banned. If you are a cheater you can avoid ban by disqualifying all your cheating submissions until we get to you. After mentioned thread all users from top100 (and then top256) will be x-rayed.


Please check out a new contest CONSTANT. It's dedicated to problems in which you have to evaluate as many digits as possible of famous constants like π, e or φ.

Even if you are not interested, you may find there a link to the world records in this field. You may be surprised.

Do you teach algorithms, data structures or programming paradigms?

This is just a short message to remind you about SPOX which is dedicated for your academic activities.


Codecha (True Programmers' CAPTCHA) - the new project based on Sphere Engine - has just started.

Badges for SPOJ by Ricardo Bittencourt (ricbit)

Ricardo Bittencourt (ricbit) made SpojTweet to track your progress on SPOJ, and give badges for your achievements. Please have a look at an example page from the site, an exemplary tweet sent by a site, Ricardo's SPOJ forum post and more SPOJ tools.

Are you a novice in programming?

Please consider Simple Programming Problems. Comments and suggestions are very welcome here.

Programacion Competitiva Bolivia

A new subSPOJ for those who would like to try problems from Bolivian OI, ICPC and other contest. Please join bo.spoj.com.

High School Programming League 2012/13 final results. The winner is Tomasz Rewak. Congratulations!

Top 5 contestants:

1 Tomasz Rewak II Liceum Ogólnokształcące im. Stanisława Wyspiańskiego w Legnicy, Poland
2 Mario Lipovsky Spojená škola Novohradská, Slovakia
3 Aleksandar Ogrizovic Gimnazija "Veljko Petrović", Serbia
4 Tomasz Zwornicki I Liceum Ogólnokształcące im. Tadeusza Kościuszki w Łomży, Poland
5 Wojciech Zieliński Zespół Szkół UMK: Gimnazjum i Liceum Akademickie, Poland

more ...

Top 3 Teams:

1 Gimnazija "Veljko Petrović", Serbia
   (Coach: Duško Obradović)
2 Zespół Szkół UMK: Gimnazjum i Liceum Akademickie, Poland
   (Coach: Anna Beata Kwiatkowska)
3 Zespół Szkół Techniczno - Informatycznych w Gliwicach, Poland
   (Coach: Daniel Kuśka)

more ...

ITRIX Online Programming Contest

ITRIX 2013 is a 5-hour ACM-ICPC style online programming competition organized by College Of Engineering Guindy, India. Contest starts 2013-02-27 16:30:00 SPOJ time. All college students are invited to participate.

SPOX Beta – the online grader for your programming courses

It is our pleasure to announce a new system dedicated to teaching programming. SPOX (http://spox.spoj.pl) has been built upon the same engine as SPOJ, but dedicated to teaching in the context of private lessons or regular courses at different levels, starting from beginners to advanced university students.

The Cube - new SPOJ Cluster

We are happy to announce that we have a new cluster of judging machines on SPOJ. The Cube (that's how we called our new cluster) consists of machines with Intel Pentium G860 3GHz on board. Read more on our Facebook page: http://www.facebook.com/pages/SPOJ/248106793203.

High School Programming League 2012/13

From now on, you are cordially invited to register for the fifth edition of a High School Programming League and to try the test problem. The first problem set series starts on Monday, September 24.

SPOJ in Armenian

If you understand Armenian, please have a look at the problems collection prepared by Andreasyan.

Shorten it!

Carefully selected problem set and ranking system by Piotr Kąkol dedicated for code golfing - this is Shorten. Everyone is invited to participate and have fun.

NWERC 2011 Semi-Live online contest

The open edition of NWERC 2011 will take place at 27 November 2011 10:30 (SPOJ time). Everyone is invited!

Interactive problems

New kind of problems has been introduced on SPOJ - interactive problems that allow to talk with the judge! (sample problems: MSTRMND, KULE, PPP07D and NUMGUESS). Go here to find out more.

BBone an add-on for phpBB forums is available.

The BBone allows to share source codes and provides the ability to compile and run them. Beside syntax highlighting, testing source codes against user input, it allows to create mini-contests for forum co-members. Read more ...

Useful tools

They are described on our facebook page:
Users' stats
Another good users' stats
SPOJ Rank Tracker - Firefox Add-on

SPOJ Backup Tool

Backup your solutions! Find out more on our facebook site.

Problems Classification

Read about Problems Classification tools on our facebook site.


Ideone.com - new project based on Sphere Engine - has just started. Ideone.com is a pastebin, but a pastebin like no other on the Internet. More accurate expression would be online mini IDE and debugging tool. It allows to execute code with custom input data in 38 programming languages and to share it with friends and teammates. We hope you find it useful!


We are delighted to announce the opening of the new portal based on the Sphere Engine. With Scarky.com you can place programming challenges and other riddles directly on your site!

Advanced user statistics

We recommend this on-line tool (by VNOI Team) for visualizing the activity of SPOJ users.

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