1. What is Coding Chill-Out?

Coding Chill-Out competition is all about solving programming challenges in the most innovative way possible. It is a platform for graduate/undergraduate students and IT professionals.

2. What is the goal of Coding Chill-out contest?

The main objective is to provide an opportunity for students and professionals to showcase their skills and connect local companies with programming community.

3. How do I register for this competition?

All contestants must register and provide the required information at the Contest Website, located at http://codechillout.sphere-contest.com/  Registration openes on 26th May 2015.  Please note that although registration will remain open throughout the duration of competition itself, however, contestants must register, (and their registration accepted) before they able to participate in the contest.

4. How does it work?

Participants compete by completing an online programming challenge. Each participant will be awarded points based completeness and performance. The top 3 participants will be awarded prizes.

5. When does it start?

Coding Chill-out has two rounds.

First round (remote):

Starts on June 27th at 20:20 (GMT+2) and will run up to the 3rd July 22.20 (GMT+2)
This round is open for all registered users.
The contestants can code in their own preferred Chillout Coding zone (e.g., at home, on the beach, park).

On-site round & Celebration:

This will take place in Microsoft Innovation Centre at Skyparks in Luqa on the 11th July 2015.

6. What are the prizes?

The top 3 participants in the competition will be given cool prizes. Further details will be released just before the competitions start.

7. What programming language should I use?

You can use:

  • C#
  • Python
  • C
  • PHP
  • C++
  • Java 7

8. What are the scoring criteria?

The scoring system is automated by the Sphere Contest platform powering some of the largest programming platforms worldwide, such as Spoj and Codechef.

9. Why does SPOJ rock so much?

There is also an amazing community (+300k users) behind SPOJ, with many active members willing to help out on the community forums. SPOJ allows users to add their own challenges, organize programming contests, and compete for the highest ranks. It is used by both novice and confirmed programmers. For many, it serves as a training platform before large programming contests. It has been created out of pure passion for programming by theoretical computer scientists and is quite laid-back, which you can easily tell from the motto of the site: “Where Hackers eat Crackers.

”Sphere Online Judge (SPOJ) is a treasure-trove of thousands of coding challenges which will keep you busy for weeks. The challenges at SPOJ range from simple coding problems to hard algorithmic challenges that require some serious problem-solving skills, like finding the best heuristics for NP-hard problems. SPOJ lets you code in almost every programming language you can imagine and provides you with feedback on your solution, which may for some challenges contain additional hints."

9. Are there any sample problems?

Sample problems can be found here.

10. What are the scoring rules?

The score of each contestant will be the total of all scores received for individual problems. Unless otherwise stated, all problems will be graded in a scale of 0 to 10.

A solution which works correctly and within the specified time & memory limits for all the tested data sets will receive a full grade of 10. Partial grades will be awarded for solutions which work as expected for some data sets, but exceed the imposed limits or behave incorrectly for other datasets.

We reserve the right to disqualify any solutions which:

  • are the result of collaboration with other contestants,
  • rely on extensive reverse-engineering of test data,
  • whose principle of operation is unable to explained by the contestant when requested to so,
  • in which the contestant displays extreme disregard for basic rules of good programming style & coding practice (obfuscated or completely unreadable code, etc.).

11. What feedback do I get from the system when I submit a solution?

After a few moments you will see one of the following results:

  • accepted - your program ran successfully and gave a correct answer. Congratulations, you have solved the problem!
  • wrong answer - your program ran successfully, but gave an incorrect answer. Most probably your program contains a bug, or you are not interpreting the problem text correctly.
  • time limit exceeded - your program was compiled successfully, but it didn't stop before the time limit. This may be because the algorithm is badly designed (too slow), or because it contains a bug, e.g. it goes into an infinite loop, or hangs up, expecting some input data.
  • compilation error - your program couldn't be compiled; the details of the compiler error can be accessed from the web interface.
  • runtime error - your program was compiled successfully, but it exited with a runtime error or crashed. You will receive an additional error message, which is most commonly one of the following:
    NZEC (non-zero exit code) - this message means that the program exited returning a value different from 0 to the shell. For interpreted languages (including JAVA) NZEC will usually mean that your program either crashed or raised an uncaught exception.
    SIGSEGV (signal 11) - the most common error for non-interpreted languages: a "segmentation fault" of the program. This may be caused e.g. by an out-of-scope array index causing a buffer overflow, an incorrectly initialized pointer, etc.
    SIGXFSZ (signal 25) - "output limit exceeded". Your program has printed too much data to output (typically more than 25MB).
    SIGFPE (signal 8) - "floating point error" - an error of the arithmetic co-processor, such as division by zero, etc.
    SIGABRT (signal 6) - raised by the program itself, e.g. by making the abort() system call.
    other - there are other signals which can cause program to terminate, all the remaining ones are simply displayed as other.

Note that the form of an error message details depends on language and we pass all the result directly to you. In particular it means that you can get no detailed information about error in your code.

We hope your answer gets accepted first time around! If not - don't worry; you can resubmit your solutions as many times as you want.

12. Can the contestant choose the complexity level of the problems?

No, the problems are the same for everyone. Try to come up with the fastest correct solution you can for each problem. Partial grades will be awarded for solutions which work correctly for some test sets of data, but exceed the imposed limits or behave incorrectly for others. All problems carry equal points, so you might consider solving the problems which seems the easiest first!

13. How long will it take to complete the competition problems?

You may submit solutions for the set contest problems from the second the contest opens till the second it closes. No extensions will be granted. The expected time commitment of a contestant may vary, but if your goal is to win, we would advise against trying to solve all problems on the very last day of the contest, because in the event of a tie, the earliest entry will win! Also, try submitting your solution as soon as you have it ready - there is no penalty for incorrect solutions!

14. Can the contestant return to complete the contest, or would it have to be completed in one block of time?

Feel free to adopt your preferred time planning, and to submit solutions to the problems from whenever you like. Note, however, that submitting everything on the last day is probably not the best strategy.

15. Oops, I don’t remember my password, what should I do?

Please e-mail us on support@recruitcoders.com

16. What are the eligibility requirements for the contest?

First remote session is open for any registered users who wish to share passion for coding. Feel free to join us from your own Coding Chill-out zone at any location worldwide!

The second round is open for participants who are based in Malta.

Students: you need to be currently enrolled as a student in a Maltese institution (University, IT school etc.) Students will be required to present school ID at the registration desk.

Professionals (pro): Any professionals who wish to code and be part of the most rocking developers event in the country. Professionals will be requested to present ID card.

17. I am not coder/ don’t know how to programme at all, can I take part in this event?

You can try, but the organizers have the right to quickly test contestants’ skills before allowing a participant to take part in the on-site contest  to ensure that each contestant has what it takes to be a coder at this Chill-out event. Prove you are programmer here: https://codecha.org/

18. How to write programs for online judge systems?

The crucial part of the platform is automatic scoring of the submitted solution. As you probably know designing a program which verifies correctness of the given source code is impossible even in theory. Therefore your solution is tested on representative and reliable model input data. We will execute your solution with our input file to produce output file. Obtained output file is compared with model output file (or checked for its correctness other way).

Model input file is provided to the standard input (stdin) of your solution. We expect that your program produces output to the standard output stream (stdout). In every language all typical functions for printing and reading are using mentioned standard streams. Please note that you don't suppose to open any files or handle with command line arguments.

Please consider this simple problem as representative tutorial for solving problems on online judge platforms:


Calculate the sum a+b for given integers a and b.

There will be provided certain number of data sets for the problem. Each data set consist of two integer numbers ai and bi separated with a space, where i is the number of the data set. Data sets are separated with a new line.

For ith data set print the value of ai + bi. Answers should be separated with a new line.


2 3
10 -2
-1 5
-3 -3
0 1



As you can see the problem is to calculate the sum of two numbers but the input specification requires you to handle multiple instances of the problem. You can design a solution in the way that separates those two aspects. Here is a possible solution in C language:


#include <stdio.h>

struct input
  int a;
  int b;

int solution(struct input in)
  return in.a + in.b;

int main()
  struct input in;
  while (scanf("%d %d", &in.a, &in.b) != -1) {
    printf("%d\n", solution(in));
  return 0;


Of course it is not necessary to build additional structures and we present it only for educational purposes. The most obvious solution would be more similar to the following one:


#include <stdio.h>

int main()
  int a,b;
  while (scanf("%d %d", &a, &b) != -1) {
    printf("%d\n", a+b);
  return 0;


There is also one common mistake which appears in new user's codes. When it's said that you should read two numbers from the input you cannot include any user readable interface for that. When you add any prompt message (e.g. printf("Number a is: ");) it will make your program's output file invalid in terms of output specification.

19. Scoring

Internal scoring for submissions

Each accepted submission gets points. If the solution to the problem can be either accepted or not (we call such problems binary) the score for submission doesn't matter therefore is equal to 0. For problems with many test cases the score is usually proportional to the number of correctly solved test cases.

During Coding Chill-out contest participants will face both types of problems.

Binary problems:

  • TEST
  • Small factorials
  • Add two numberes
  • Reverse array
  • Gluttons
  • HTML tags

Non-binary problems

  • Prefix-suffix balance (3 test cases, proportional scoring with the max score = 100)
  • Simple Numbers Conversion (5 test cases, not proportional scoring with the max score = 10 and detailed scoring precised in the problem description)
  • Ladybugs race (10 test cases, proportional scoring with the max score = 100)

If the problem has many test cases each of them will be independently applied to your program therefore you don't need to prepare your program for this situation.

Note that the submission score is strictly related to its correctness and fullness. For example you can submit partially correct (or not very efficient) solution and obtain some partial points for the problem. The score of the submission is not a measure of problem difficulty.

Scoring for ranking

The number of ranking points is assigned to each problem (you can see these values on the list of problems of each round) and reflects the problem’s difficulty.

For binary problems, you will earn the maximum number of ranking points for every accepted solution. For non-binary problems there are few rules:

  • The author (or authors) of the best solution (in terms of submission score) gets maximum number of ranking points.
  • The number of ranking points of user's solution has the same proportion to max ranking points as its submission score to submission score of current best solution. For example if the best solution has 70/100 submission score and the user's submission has 50/100 submission score then the proportion is 5/7. Therefore for the problem of ranking points = 35 the user's solution is worth 25 ranking points.
  • The assignment of ranking points may change after the submission of a better solution. To continue the previously given example when another user submit a solution which obtain the submission score of 90/100 (which is new best result) then all user's rankings points are recalculated. The user with the submission score of 90/100 has now the maximum number of points (35). The user who was leader before has his best solution with the submission score of 70/100 therefore his current number of ranking points is equal to 35 * 7/9 which is roughly 27. The user with the submission score of 50/100 also lost few points and now he has 35 * 5/9 which is roughly 19.


For any questions contact us.

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