MCO Contest Format and Rules

These are the latest MCO rules. Old MCOs may follow different rules as rules change.

New updates in 2026 are marked in red.

Contest Format

Contest duration: 3-4 hours (check invitation letter).
There will be 3-4 problems.
- Problems may or may not be sorted in difficulty order.
Only C++ is allowed.
- This is because the IOI only guarantees support for C++.
IOI format will be used.
- Contestants are ranked by total points only.
- There is no penalty for time nor incorrect solutions.
- Each problem will have several subtasks: They add additional constraints to the problem and provide partial points if solved.
- Contestants may submit a solution to each task at most once per minute.
  - This restriction does not apply in the last 15 minutes of the contest.
- Contestants may submit at most 50 solutions for each task. This limit may be increased for some task types.
Contest Management System (CMS) (also used in IOI) will be used to run the contest.

Contestants must bring their own laptops and chargers. Charging ports will be provided.
Pre-written templates, local files (that isn’t AI), and printed materials are allowed.
Internet access is NOT allowed except to the following:
- The contest website.
- USACO IDE.
- cppreference.com, the C++ reference.
Usage of artificial intelligence (such as ChatGPT, GitHub Copilot, Amazon CodeWhisperer) is not allowed.
- For VS Code users: Please disable Copilot before the contest. Go to settings and search for chat.disableAIFeatures.
Communication other than with the contest committee is not allowed. This includes posting new questions on a forum (e.g. StackOverflow) during the contest.
Additional equipment (e.g. mouse, keyboard, tablet, earphones) is allowed. However, it must not disturb other contestants (e.g. make loud noises).
Contestants need to record their screen during the contest to be uploaded immediately after the contest. The recording must be less than 1GB in size. Contestants may follow the instructions for screen recording.

Three types of medals will be awarded: gold, silver, and bronze. The champion will receive a champion certificate.