Submission deadline passed:
31 December 2004

Call for tasks

The IOI Scientific Committee invites everyone in the IOI community to submit tasks for the IOI'2005 competition. The deadline for submitting tasks is December 31, 2004; rough guidelines for tasks and instructions for submission are given below.

IOI Competition Tasks

IOI tasks are typically focused on the design of efficient, correct algorithms. Input and output are to be kept as simple as possible. The competition tasks from previous IOIs can provide, by example, good guidance on the desired composition of tasks; a large collection can be found at the IOI Secretariat site at However, the nature of previous tasks should not constrain the design of new tasks; the submission of novel tasks types not yet seen in IOIs is encouraged. A brief description of some of the types of tasks used in past IOIs (again, not meant to be restrictive) starts at line 326 of the IOI SC Guidelines:

To ensure a fair and interesting competition for all, tasks should satisfy the following conditions:

  • The tasks should not have been seen by any potential IOI'2005 contestants.
  • The tasks should not have been used in any similar competition.
  • The tasks should be solvable by IOI competitors during an IOI contest round.
  • The task descriptions should be unambiguous and easy to understand.
  • The tasks should be culturally neutral.
  • The tasks should be innovative.

What to Submit

A task submission must contain a statement of the task in English, preferably formatted in plain text. If diagrams are needed as part of the task description, please use LaTeX's picture environment or MS Word's diagram drawing feature to create them, or enclose them as eps or pdf files, if possible. In addition, the submission must also contain a description of the desired solution to the task (a description of an algorithm which should receive full marks). Preferably, the submission should also include implementation of the desired solution (in C/C++ and/or Pascal) and analyses of alternative solutions. Suggestions for grading, test data or ideas for generating test data, the motivation behind the task, and any comments related to the task are also welcome. Inclusion of extra information, especially coded solutions and grading suggestions, is highly appreciated.

A task submission must also include a contact address (preferably one e-mail address) and background information on the task author(s): affiliation, country, and a description of the author's role in the IOI or national olympiad, including training duties, over the period from IOI'2004 to IOI'2005.

How to Submit

To submit a task electronically, please:

  • use the submission form, or
  • encrypt and "ASCII armor" all material with PGP using Marcin Kubica's and Krzysztof Stencel's public keys (see here), and email the encrypted output to

For example, to send the file task.txt use the following UNIX command:

        gpg --armor --encrypt --recipient \
        --recipient --output - task.txt | 
        mail -s "IOI 2005 task submission"
        pgp -a -e task.txt -o - | 
        mail -s "IOI 2005 task submission"

Please do not send unencrypted task materials over email; any task ever sent unencrypted will be discarded. The deadline for receipt is December 31, 2004.

Tasks may also be submitted through the postal service; in this case it would be best to email a floppy disk or CD-ROM with electronic versions of all submitted materials, but paper submissions will also be accepted. The deadline for receipt is December 31, 2004. Address the materials to:

Marcin Kubica
Institute of Informatics
Warsaw University
ul. Banacha 2
02-097 Warsaw


Please note that all material submitted becomes the property of the IOI, and that by submitting the author is assigning the Copyright and all rights to the submitted materials to the IOI.

Also note that task authors have the responsibility to keep submitted tasks completely confidential. We assume that authors understand what this means. In particular, this means that task authors and their collaborators must not use a submitted task, or a variant thereof, or techniques specific to that task, in any competition or training until IOI 2005 has ended. In case of doubt, contact the ISC. Note that we do not wish to forbid authors of submitted tasks to be involved in other competitions and training, but we do ask them to take all necessary precautions to safeguard confidentiality.

What Happens Next

Receipt of submissions will be confirmed via the provided contact address.

At various moments during the preparation of the IOI 2005 competition, it is possible that submitted tasks are dropped from further consideration. However, it may still be necessary to revert such decisions later. In general, authors will not be informed prior to IOI 2005 as to whether their tasks will be used at IOI 2005 and in what way.

Authors of submitted tasks will be recognized during IOI 2005 by listing their name, affiliation, and country (unless they specifically decline this).


Submission deadline: 31 December 2004
Language: English
Text format: plain text preferred
Diagrams: LaTeX picture environment, MS-Word-drawn diagrams, eps or pdf
Multiple files for one task: in single zip or compressed tar archive
Multiple tasks: submit separately
Minimum contents of submission:
  Contact address (preferably e-mail)
  Name, affiliation, country, and olympiad-role description of author(s)
  Task description (including required diagrams)
  Description of desired solution
Optionally include:
  Algorithms coded in C/C++ and/or Pascal
  Suggestions for grading
  Test data, test data specifications
  Alternate solutions or expected near-solutions
  Complexity analysis
  Background information on task
  Any other comments relevant to a task