Important Notice: In order to register for the Team Formation Test, students must attend at least 1 regular training session to become an official Training Team member.

Please visit this page frequently for rule updates.

Updated on 2021-04-13: Please check your assigned venue from the Contest page. CityU Guest QR codes have been sent to students assigned to CityU.

Date: 17th April, 2021 (Saturday)
Reporting Time: 1:00 – 1:30 p.m.
Reporting Venue: Mong Man-wai Building, City University of Hong Kong
(near the entrance facing walkway between Festival Walk and Yeung Kin Man Academic Bullding)
Pui Ching Middle School
(school entrance)
Event Time: 2:00 – 7:00 p.m.
Competition Venue: MMW-1411 and MMW-2462,
City University of Hong Kong
E308 and E310,
Pui Ching Middle School
Required Documents: Hong Kong Identity Card (for age verification)
Student ID Card
Health Declaration Form
For students assigned to CityU: CityU Guest QR code (for entering CityU campus)

All competitors must abide by our Epidemic Prevention Measures.

Competition Details and Eligibility

Criteria for participating in the TFT
  • An individual medal winner in HKOI 2020/21.
  • Has an HKOI Online Judge account with the role “HKOI Trainee (2021)”.
  • A full-time Hong Kong secondary school student at all times between 1st Sept 2020 and 1st June 2021.
International Olympiad in Informatics (IOI) National Olympiad in Informatics (NOI) Asia-Pacific Informatics Olympiad (APIO)
Date 20th – 27th June 2021 24th – 30th July 2021 22nd – 23rd May 2021
Location Remote; hosted by Singapore TBC: On-site (Zhejiang) or Remote Online; hosted by Indonesia
Additional Criteria
  • Born on or after 1st July 2001
  • A holder of Hong Kong Permanent Identity Card
  • Born on or after 1st July 2002
  • A holder of Hong Kong Permanent Identity Card
  • Able to read simplified Chinese
  • Born on or after 1st July 2001
  • A holder of Hong Kong Permanent Identity Card


Students who do not meet the general criteria but have the role “Non Trainee (2021)” may participate as observers.
Eligible students and observers may register through the judge’s Contests page on or before 11th April 2021 (Sun). Walk-in is NOT ALLOWED.

Special Notes

The training team reserves the right to move the Team Formation Test online or to assign students to a venue other than City University of Hong Kong. We may also reject some or all observers if there is insufficient capacity.

Allowed Programming Languages

The only allowed programming language is C++17.


Each contestant will be assigned a workstation to connect to the competition Virtual Machine via Chrome Remote Desktop. Contestants must not interact with the workstation outside the Virtual Machine.

Virtual Machine


Virtualization: Amazon AWS “c5.xlarge”
CPU: Intel Xeon Platinum 8275CL “Cascade Lake” @ 3.0 GHz up to 3.6 GHz all core turbo. 2 cores 4 threads (exposed to the VM as 4 CPUs)
Memory: 8 GB + 2 GB swap
Disk space: At least 1.5 GB free space on local disk + 100 MB network drive quota.

Personal Keyboards

Contestants are recommended to bring one personal keyboard and one mouse for use in the competition. Wireless devices or devices that require installation of drivers, and mechanical keyboards fitted with “blue” switches (or equivalent) are not allowed. The adjudicators reserve the right to examine and disallow any device.

Installed Software

Operating System: Debian 10 “Buster”
Display Manager: XFCE4
Google Chrome
Visual Studio Code with the following extensions: C/C++, Code Runner
G++ 9.3.0

Submitted programs will be compiled using the compilers and compilation flags specified in the Help page of the Online Judge. Participants are not allowed to use any of their own resources in the competition.


The paper is only available in English. The paper shall consist of several programming tasks. Each task may carry different points. Each task will be further divided into one or more subtasks. Each subtask may carry different points.

The syllabus consists of the latest version of the IOI syllabus, and all materials covered so far during this year’s Regular Training sessions.

Submission of Solutions and Adjudication

Contestants should submit their solution source codes to the Online Judge. The judge will compile the source codes submitted by contestants, and then assess the compiled programs by testing them with a set of data unknown to the contestants and a marking scheme to be determined by the Adjudicators. To score points for a subtask, contestants’ programs must be correct for all test cases in that subtask.

Contestants will receive feedback about their submissions, including type of error first encountered (if any) for each subtask. A contestant’s final score will be the sum of points received from solved or partially-solved subtasks. Contestants may submit at most once per task per 60 seconds, and at most 50 times per task.


During the competition, contestants are allowed to seek clarification on the wordings of the tasks from the Adjudicators by using the competition web interface. Should the condition deem necessary, the clarifications will be announced to all contestants. Clarification related to the solutions will not be entertained.

Any queries about the competition should reach the Chief Adjudicator within 5 minutes after the end of the competition, before leaving the venue. The decision of the Adjudicators will be final.


There is a small chance that the score may change due to change of tests, or indeterminacy of the contestant’s submission. Indeterminacy may arise intentionally due to the use of pseudo-random number generators, or unintentionally due to programming bugs or marginal running time. The Hong Kong Olympiad in Informatics Organizing Committee reserves the right to re-evaluate submissions, and the final score will be that yielded by the final evaluation.


If contestants wish to drink water or go to the toilet during the test, they must make a request using the Questions / Announcements feature. Contestants may only drink water or go to the toilet upon approval by the invigilators. The invigilators may reject any request that deemed excessive, or if another contestant is visiting the toilet. It will be regarded as cheating if you drink water or leave the seat without the invigilator’s approval.

Selection Algorithm

One ranking for each external competition will be produced. For each competition:

  • – The ranking will only include the students who commit to attend the competition.
  • – Students will be ordered by the total score.
  • – In case of ties, compare their last submission that resulted in a score increase. The one with the earlier submission time shall rank higher.

Then, the potential delegates will be selected as follows:

Step 1: 4 IOI members

The top 4 students in the IOI ranking will be selected.

Step 2a: 1 NOI (Class A) members

The top students in the NOI ranking will be selected.

Step 2b: 3 NOI (Class A) members

The next 3 students in the NOI ranking, excluding the selected IOI members, will be selected.

Step 2c: 1 NOI (Class A) member

If any of the 4 NOI members selected from Steps 2a-2b is female, then the next student in the NOI ranking, excluding the selected IOI members, will be selected.
Otherwise, the next female student in the NOI ranking, excluding the selected IOI members, will be selected.

Step 2d: 2 NOI (Class B) members

The next 2 students in the NOI ranking after the ones selected in Step 2b, excluding the selected IOI members, will be selected.

Step 3: 60 APIO members

The top 60 students in the APIO ranking will be selected.

Other Opportunities

Should there be other learning opportunities, the training team may select members with reference to the TFT ranking, APIO results and eligibility criteria.

Required Commitment and Results Announcement

The training team will submit the test results, student profiles, attendance records and comments from the trainers to the Hong Kong Association for Computer Education and the Education Bureau for review and approval. Potential delegates (including backup members) will be requested to sign a Commitment Agreement and Parent’s Consent which must be returned to the Organizing Committee within 5 days in order to be considered further. Except for APIO, withdrawal will not be permitted under any circumstances once the document has been signed.

Potential delegates will be notified of the final selection results. The HKOI Organizing Committee’s decision shall be final.

All selected members are required to attend team training sessions in May – July.