Competition Tasks
IOI tasks focus on efficient, correct algorithms with simple input and output. IOI needs both simple and difficult tasks that are creative. We actively encourage easy problems that still require insight and allow multiple approaches.
Recent task collections:
- IOI 2025 — tasks
- IOI 2024 — tasks
- IOI 2023 — tasks
- IOI 2022 — tasks
- IOI 2021 — tasks
- IOI 2020 — tasks
- IOI 2019 — tasks
- IOI 2018 — tasks
- IOI 2017 — tasks
See the broader archive here. New task types are welcome, including reactive and output-only tasks, and tasks assessed beyond CPU time. See the IOI Syllabus as a guideline.
Eligibility & Integrity
Conditions
- Not seen by potential IOI 2026 contestants.
- Not used in any recent similar competition.
- Solvable during an IOI round.
- Unambiguous, easy-to-understand statements.
- Original and/or innovative.
Confidentiality
Submissions remain confidential until IOI 2026 concludes. After that, authors are free to use their tasks. If considered for IOI 2027, confidentiality extends accordingly.
Task Criteria
Include the following:
- Statement in English (PDF preferred), with diagrams if needed.
- Description of the desired full-score solution.
- Author contact and background: name, email, affiliation, country, and roles in IOI or national olympiad from IOI 2024 to IOI 2026.
- PGP key ID if you want ISC feedback.
Strongly recommended:
- At least one C++ reference implementation.
- Alternative solutions analysis.
- Grading suggestions.
- Test data or generation ideas.
- Task motivation.
Submission Process
Bundle all materials into a single file (.zip or .tgz for multiple files) and submit online here.
- Authorization code: samarkand
- Encryption: do not encrypt manually; the upload page handles it.
- Language: English
- Format: PDF preferred
- Multiple files: zip/tar into a single archive
- Multiple tasks: submit separately
If the authorization code is not yet announced, check back on this page or the ISC portal.
Notes
By submitting, the author grants IOI an exclusive license to use the material until IOI 2026 ends, and a perpetual non-exclusive transferable license to reproduce it. The author guarantees compliance with this call and will not disclose materials to third parties during the exclusive period.
Authors and collaborators must not use the submitted task, its variants, or techniques specific to it in any competition or training until IOI 2026 ends. If in doubt, contact the ISC.
What Happens Next
Submissions will be acknowledged via the provided contact. The Scientific Committee will review all submissions and select a shortlist of around 10 tasks, six of which are expected to be used at IOI 2026 in Uzbekistan.
Authors of shortlisted tasks may be invited to attend IOI 2026 as guests (travel typically at the author’s expense; stay covered by the host). Whether a shortlisted task is used or modified will not be revealed before the competition.
All authors will receive feedback from the ISC. Authors of tasks included in the official competition will be credited on the IOI website (unless they decline). Problems will be available under the CC-BY license.
Summary
- Submission deadline: TBA
- Language: English
- Text format: PDF preferred
- Multiple files: single zipped/tarred archive
- Multiple tasks: submit separately
- Minimum contents:
- author info (name, email, affiliation, country, roles)
- task statement
- desired full-score solution description
- Recommended:
- C++ implementation(s)
- grading suggestions
- test data
- alternative or near-expected solutions
- motivation and other relevant notes
- Submission site: https://isc.ioinformatics.org/taskbox/
- Contact: hsc@ioi2026.uz