These are the official rules governing the NOI.PH 2021. Important changes to the rules since NOI.PH 2020 are highlighted in red.

I. Eligibility

  1. The contestant must be enrolled at a school not higher than secondary education, for the majority of the period 1 September to 31 December 2020. (IOI S2.5.1)
  2. The contestant must be a Filipino citizen, or enrolled at a school in the Philippines for the majority of the above stated period. Exceptions to this rule may be requested by emailing [email protected] (IOI S2.5.1)
  3. The contestant must be born on or after July 1, 2001. (IOI S2.5.2)
  4. The contestant must have registered officially through the registration form.
  5. The contestant must have:
    1. A valid email address
    2. A valid Codeforces username

II. Contest Structure

  1. This is an individual competition.
  2. Rounds. The competition will be split into two rounds:
    1. The Online Elimination Round
    2. The On-Site Final Round
  3. Topics. In general, tasks follow the Official IOI Syllabus. However, a small number of tasks may require topics listed as “Excluded, but open to discussion,” or “Explicitly excluded” in the official IOI syllabus.
  4. Languages.
    1. Online Elimination Round. All programming languages supported by Codeforces is allowed for the Online Elimination Round. The exact compilation and execution commands to be used for each language is to be published in a competition environment specification and made known sufficiently in advance to all registered participants.
    2. On-Site Final Round. Only C++ and Python 3 are allowed for the Final Round. All programming languages used in the Online Elimination Round by at least one invited On-Site Final Round participant is allowed for the On-Site Final Round, but more languages may be allowed at the discretion of the organizing committee. The exact list of allowed programming languages and the exact compilation and execution commands to be used for each language are to be published in a competition environment specification and made known sufficiently in advance to all invited participants.
  5. Clarifications. Clarifications pertaining to a task must be publicly filed by the contestant using the clarification system made available as part of the contest system.
  6. Subtasks. Unless otherwise stated, a task is divided into several subtasks.
    1. Each subtask consists of one or more test files.
    2. A subtask follows additional constraints and simplifying assumptions.
    3. Each subtask is worth a certain number of points.
  7. Scoring.
    1. Subtasks. Unless otherwise stated, answering all test cases and test files of a subtask merits a certain number of points, indicated in the problem statement of each task.
    2. Submission. The score of a contestant for a submission to a task is the sum of the scores obtained for each subtask of the task.
      1. The total score is usually 100.
      2. There are no penalties for incorrect submissions.
    3. Task. The score of a contestant for a task is the score of the highest submission to that task.
    4. Contest. The total score of a contestant for a contest is the sum of the scores over all the tasks.
  8. Ranking. For one contest, participants are ranked based on the following in decreasing order of importance.
    1. Score, the total score of a contestant.
    2. Time penalty, the time the contestant reached that score.

III. Online Elimination Round

  1. Elimination Round. The Elimination Round will:
    1. Be held online, on Codeforces.
    2. Consist of one contest lasting nine to ten days, with the expectation that the contestants will solve the tasks during their free time.
  2. References.  Contestants are allowed to use reference materials, physical or digital, that were published before the start of the contest.
  3. Invitation to the Final Round.
    1. Top 30. Thirty (30) contestants in the Elimination Round will be invited as official finalists to the Final Round provided that they:
      1. Satisfy all eligibility criteria.
      2. Have not been disqualified.
      3. Have confirmed willingness and ability to attend the On-Site Final Round.
      4. Are among the top six (6) contestants from their school.
      5. Are among the top thirty (30) contestants satisfying all criteria above.
    2. Additional contestants. Depending on the logistical limitations of the venue of the On-Site Final Round, some contestants may also be invited as non-finalist participants or observers. No such invitations will be made if the Final Round is held online. Non-finalist participants and observers are:
      1. Not shown in the official standings for the Final Round.
      2. Not eligible for medals in the Final Round.
      3. Not eligible for invitation as official participants to the IOI Training Camp.
      4. Not eligible for invitation to the IOI.
    3. Promotion from non-finalist participant to official finalist. In case some official finalists are unable to attend the On-Site Final Round for any reason, some non-finalist participants may get promoted to official finalists. The exact rules for promotion are detailed at the end of this page.

IV. On-Site Final Round

  1. Final Round. The Final Round will:
    1. Be held on-site if logistically feasible and online if not. in a competition environment specified and made known sufficiently in advance to all invited participants.
    2. Consist of two contests, each lasting for five hours.
  2. Official contestants. An official contestant to the Final Round must:
    1. Satisfy all the eligibility requirements.
    2. Have been invited to the Final Round.
    3. Have confirmed their attendance by responding to the invitation on or before the specified deadline.
    4. Have included a copy of their student ID in their response to the invitation.
  3. Student ID. Contestants must bring their student ID to the contest venue. Failure to do so may result in disqualification.
  4. References.
    1. Contestants may not bring access any reference materials or use digital devices without prior approval during the contest proper.
    2. Contestants are not allowed to access websites aside from those explicitly allowed in the competition environment specification.
  5. Communication. Contestants must not communicate with anyone but the members of the organizing committee during the contest proper.
  6. Ranking. Participants are ranked based on the following in decreasing order of importance:
    1. Total score, the total score of a contestant across all contests in the Final Round.
    2. Total time penalty, the sum of the time penalties of a contestant across all contests in the Final Round.
  7. Medals.
    1. Gold. A gold medal is awarded to the highest-ranked contestant.
    2. Silver. A silver medal is awarded to the second and third contestants.
    3. Bronze. A bronze medal is awarded to the fourth to the sixth contestants.
  8. Invitation to the IOI Training Camp.
    1. Top 15. The top fifteen contestants in the Final Round will be invited as official participants of the IOI Training Camp.
    2. Additional contestants. The next-ranked participants may be invited as official participants to the IOI Training Camp as alternates.
    3. Failure to confirm. Failure to confirm within the amount of time given may result in the forfeiture of the invitation.

V. IOI Training Camp

  1. Pre-Selection Training Sessions. The first part consists of training sessions and will span several weeks. These sessions may be held online.
  2. In-House Training. If logistically feasible, the second part of the IOI Training Camp will be the In-House training. Participants are to stay in-house for the whole duration.
  3. In-House Round. An in-house round will be administered towards the end of the in-house training if it proceeds.
  4. Invitation to the IOI. The scientific committee will hold a meeting to decide which among the official participants of the Training Camp will be chosen to represent the country at the IOI. Criteria for the decision shall include (but are not limited to):
    1. Performance in the NOI.PH Final Round
    2. Performance in the pre-selection training sessions
    3. Performance in the in-house training, if it proceeds
    4. Performance in the in-house round, if it proceeds

VI. Disqualification

  1. Undermining the legitimacy of the contest. Contestants may be disqualified from any of the contests and training camps if the organizing committee reasonably believes that they have attempted to undermine the legitimate operation of any of the contests, by engaging in activities including (but not limited to):
    1. Providing false information about themselves during registration or concerning their eligibility.
    2. Breaching or refusing to comply with the rules.
    3. Sharing or using from others, whether intentionally or unintentionally, any information about a task, including its content or solution, before the end of a round.
    4. Displaying behavior considered to be disruptive, unethical, or unsportsmanlike.
  2. Failing to reply. Contestants may be disqualified if they fail to respond to any request for information from the organizing committee related to NOI.PH and/or the IOI within seven days of our request.
  3. Change of username. The contestant must not change their Codeforces username at any point in the contest period (from registration until the end of IOI Training Camp). Any username change is grounds for immediate disqualification.
  4. Reporting possible cases. Any harassment, cheating, or violation of these terms may be reported by email to [email protected]

VII. Detailed Rules on Invitation to the Final Round

The following steps shall be taken by NOI.PH in determining the Official Finalists and Non-Finalist Participants.

  1. Determine the capacity of the venue.
    1. Call the capacity of the venue Cap. The value of Cap is at least 30.
    2. In the event that Cap cannot be determined yet (for instance if the On-Site Final Round venue hasn’t been finalized), determine a tentative lower bound for Cap, which may be updated later.
    3. If the Final Round is held online, set Cap to 30.
  2. Determine and resolve all disqualification cases.
    1. Remove all disqualified and ineligible participants from the Official Leaderboard.
    2. In all succeeding steps, consider only contestants that remain in the Official Leaderboard.
  3. Compute the Shortlist.
    1. The Shortlist consists of the union of the following sets of participants:
      • The top 40 participants, based on the Official Leaderboard.
      • The top 40 school-qualifying participants.
        • A school-qualifying participant is a participant that is within the top 6 among all participants from the same school.
    2. No participant outside the Shortlist may be added to the Shortlist once it has been decided.
    3. No participant outside the Shortlist may be promoted to Official Finalist or Non-Finalist Participant.
  4. Divide the Shortlist into three groups.
    1. Official Finalists. The 30 top-ranked shortlist-school-qualifying participants.
      • A shortlist-school-qualifying participant is a Shortlisted participant that is within the top 6 among all Shortlisted participants from the same school.
    2. Non-Finalist Participants. The (Cap – number of official finalists) top-ranked participants in the Shortlist that are not Official Finalists.
      • Note: there is no requirement to be shortlist-school-qualifying.
    3. Wait List. The participants in the Shortlist that are part of neither of the two above groups.
  5. Repeatedly perform recomputations and promotions based on responses of Shortlisted participants to invitations.
    1. For every instance of a participant declining to attend the On-Site Final Round, remove the declining participant from the Shortlist, and perform a recomputation.
      • Note: Participants who do not confirm attendance within the deadline are considered to have declined.
      • Note: Any disqualification occurring after the Online Elimination Round Official Leaderboard has been published is considered equivalent to a declination.
      • Note: Declining is final and may not be revoked.
    2. Every time Cap changes, perform a recomputation.
    3. Recomputation consists of updating the three groups—Official Finalists, Non-Finalist Participants, and Wait List—based on the rules above with the updated Shortlist and Cap.
      • Note: Some participants that are previously not shortlist-school-qualifying may become shortlist-school-qualifying.
    4. Perform recomputations whenever necessary, at any time before the On-Site Final Round. In other words, there may still be promotions even after the deadline for confirmation of attendance has passed.
  6. Observers.
    1. Coaches may request NOI.PH to invite Observers. Address these on a case-by-case basis, and inform the Coach of decisions in a timely manner.
    2. Observers do not enter the Shortlist, nor do they influence the computation of the three Shortlist groups.
    3. The Shortlist takes priority over invited Observers.
      • Observers may be uninvited in case the venue cannot accommodate any more participants. For instance, this may happen when at least Cap Shortlisted participants have confirmed attendance.

VIII. Changes to the Rules

NOI.PH reserves the right to change these rules at any time. Such changes will be communicated to all registered participants in a timely manner.