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This is a provisional version of the competition rules. If you have any feedback, please contact .

Competition Rules


The solution provided by the contestant must be contained in one source file as specified in the task statement.

As Java Virtual Machine uses multiple threads internally, using multiple threads is allowed in all programming languages. Note that the running time of the submission will be counted as a sum of running times of all threads. E.g. if there were two threads running for 5 seconds each (thus, the program finishes in 5 seconds), then the running time of the submission will be 10 seconds.

Each task will be divided into several subtasks, each worth a portion of the total points.

Time and memory limits will be specified for every task. In general, time and memory limits will be generous (for example, double those required by the expected solution). The memory limit is on the overall memory usage including executable code size, stack, heap, etc.

Competition Schedule

There will be two competition days. On each day contestants will be given four tasks to solve in 5 hours.

Practice Session

There will be a 2-hour Practice Competition prior to the first competition day, to familiarize all contestants with the grading system. The practice tasks will be published before the EGOI. Contestants may bring printed solutions to the practice tasks, on paper only, during the Practice Competition.

Competition Equipment and Environment

Please refer to the Contest Environment page.

Task Statements

Each contestant will receive the official English version of tasks on each contest day. For those contestants who requested the translation of the tasks, an additional version of the tasks in the requested language will be provided in the same envelope with the English version.

In addition, each contestant will have online access to the official English version of tasks and all task translations in electronic format (PDF).

Finally, a working paper will be provided for each contestant.


In the competition room, blank paper and writing tools will be provided. On the competition days, contestants may not bring anything into the competition rooms, except for the following items under the proviso that they cannot transmit or store any data in electronic or printed format (other than the purpose for which they have been designed):

The following items are allowed with prior approval from the EGOI 2021 Technical Committee:

A contestant must submit these items to the technical staff during the practice competition day to use on the first competition day.

Alternatively, a contestant may submit these items to the technical staff during the time of analysis for the first competition day, to use them on the second competition day.

The technical committee checks the submitted items. Then the submitted items are given to the contestant in the competition if the technical committee has approved them.

A contestant must leave the items on their workstation if they want to continue using these items on the second competition day.

After the second competition day, a contestant must take all items with them.

Any attempts to bring any other items unlisted above into the competition rooms are considered cheating. In particular, the following items are strictly prohibited in the competitions:

For the case of snacks, the host organizing committee will provide all contestants with some amount of snacks. In cases when a contestant would still like to bring in snacks, the contestant should make sure that the snacks are not noisy or smelly, and are not disturbing for other contestants in any other way. In case of complaints from other contestants during the contest, the snack might be removed.

Except for water, contestants are not allowed to eat or drink in the contest hall. They are allowed to eat at the snack station outside of the contest hall.

Any electronic or printed materials provided by the organizers during a competition round may be used by the contestants (e.g., a Users Guide to the Contest System or any electronic documentation or reference manuals provided in the installed contest environment or on the provided grading system).

Starting the Competition

All contestants must wear their ID badges during the competition. Each contestant will have a pre-assigned workstation. Contestants should be in their seats by at least 5 minutes prior to the start of the competition. Contestants must find their assigned computer, sit down, and wait for the competition to begin without touching anything (such as keyboards, mice, pen or paper).

Assistance and Clarification

Contestants may ask the support staff for assistance at any time. Contestants may use the system to call for the support staff. In case the system is not available, contestants may raise their hands to call for the support staff. Contestants should not leave their seats until allowed to do so by the support staff. The staff members will not answer questions about the competition tasks but will deliver Assistance and Clarification Request Forms and printouts, help locate toilets and refreshments, and assist with computer and network problems.

Contestants should never attempt to fix or debug or even check computer or network problems themselves; instead, they should ask for assistance.

During the competition, contestants may submit Assistance and Clarification Requests concerning competition tasks, rules, and/or grading. Contestants may submit Assistance and Clarification Requests by using the grading system. Contestants will receive a reply from the Scientific Committee via the grading system.

Questions may be expressed either in the contestant’s preferred language or in English. But, on the grading system, contestants might not be able to type characters required for their preferred language. If required, delegation leaders will translate the questions into English after they are submitted and before they are sent to the Scientific Committee. The Scientific Committee will respond to every question submitted by the contestants during the competition. Since this might take some time, contestants should continue working while waiting for an answer to their questions.

Also, contestants may submit written questions using the provided Assistance and Clarification Request Forms. In such case, Assistance and Clarification Requests must be submitted to the support staff in the competition room.

Contestants should phrase their task-related questions so that a yes/no answer will have a clear meaning. Contestants should not ask negative questions such as “Isn’t it true that…?” because the yes/no answer to such questions may cause confusion depending on the native language of the contestants. Instead, positive questions of the form “Is it true that…?” are recommended.

Contestants are free to phrase their technical or contest related issues in any form. These issues/questions should not be related to tasks at all. Such questions will be fully clarified.

Grading System

There is no restriction on the number of times a program may be edited, compiled, and run on the workstation. The workstations have network access to the grading system.

Grading and evaluation take place on the grading system, which provides a similar execution environment to that of the contestant workstation. However, the software installed in contestants’ workstations and grading workstations are not identical. Grading workstations have programs required for monitoring and grading systems.


Contestants must submit their solutions for tasks by using the grading system. To avoid overloading the grading system, contestants may submit at most 50 solutions for each task.

Each submitted source program must be written in C++, Java or Python, it must be smaller than 256 KB, the evaluation server must be able to compile it in less than 10 seconds and at most 512 MiB of memory.


The scores will be calculated as follows:

For example, consider a contestant who made two submissions on a task that contains two subtasks. If the first submitted solution got 30 points for the first subtask and 10 points for the second subtask, and the second solution got 0 points for the first subtask and 40 points for the second subtask, then the final score for this task will be 70.


Contestants can use the grading system to view the status of their submissions and get a short report on the compilation errors of their source code.

For every submission, the grading system reports the score for each subtask. If a subtask is not fully solved, the grading system gives feedback only for the first test case among the lowest scored test cases in the subtask. The feedback includes the test case number and one of the following reasons:

For tasks with partial scores, instead of “Output is correct” or “Output isn’t correct”, the feedback gives “Accepted” or “Wrong Answer”. “Accepted” means that the submission produced a correct answer. Still, it might not get the full score, due to scoring rules explained in the task statement. “Wrong Answer” means the submission has violated some constraints or produced an incorrect answer. The precise meanings of “Accepted” and “Wrong Answer” will be explained in the task statement.

The test cases are ordered the same way in all the submissions. No information on the actual data, the output produced by the contestant solution or any other execution details will be given to the contestant.

It should be noted that the score reported in the feedback is only provisional. There are two ways how this score may change after it has been reported to the contestant:

Ending the Competition

Three warnings will be given at 15 minutes, 5 minutes, and 1 minute before the end of the competition. Each warning will be given by an audible signal. The end of the competition will be announced both verbally and by an audible signal. At the announcement ending the competition, contestants must immediately stop working and wait at their desks without touching the computers or anything on their desks. An additional announcement will be made instructing them to leave their tables and exit the competition room.

At the end of the first competition, any previously submitted items a contestant would like to use during the second competition should be left at the workstation. All other items should be taken out of the competition hall, including printouts. At the end of the second competition, contestants should remove all personal items including their mascots and dictionaries or any other previously submitted item; nothing should be left behind.


Contestants must use only the workstation and account assigned to them on each competition day. In particular:

All of the above actions are considered cheating, and may result in disqualification.

Appeal Process

Submitted solutions are evaluated using data which conform to the specification given in the problem statement, but which are hidden from contestants during the competition.

Provisional grades, based on these tests, are available immediately to contestants. In the event of an error with the test data, the Scientific Committee will attempt to, but is not obligated to follow the following process:

This hidden data will be made available electronically in the competition area during the scheduled time for analysis after each competition. Contestants and team leaders may use the contestant’s workstations to verify that the grades are assessed correctly.

A Team Leader may file an appeal by completing an Appeal Form and submitting it to the Scientific Committee at least 30 minutes prior to the final GA meeting of that competition day. The GA will be informed of where Appeal Forms can be collected, and where they can submit them to the Scientific Committee. Every appeal will be reviewed by the Scientific Committee and the team leader will be notified of the committee’s decision. All appeals and their disposition will be summarized at the final GA meeting of that competition day. In the event that every submission of a task should be re-graded and re-scored as a consequence of an accepted appeal, note that re-scoring may result in a higher or lower score for any contestant. Should anyone’s score change after grading results have been published, new results will be published again. Score changes resulting from this are not appealable.