Hello Codeforces!

VNOI Cup is back in 2025, entering its fourth season after successful editions in 2022, 2023, and 2024.

We invite you to join the mirror rounds of our contest! The official rounds are open to all Vietnamese participants, so if you're Vietnamese, we encourage you to participate in the official competition on VNOJ.

This year, we also plan to invite a few top international participants from the Open Division mirror rounds to join the Final Round onsite in Vietnam. These participants will compete in the Open Division of the Final Round — a separate onsite leaderboard from the official Vietnamese contestants.

⚠️ Please note: invited participants from the Open Division will need to cover their own travel and accommodation expenses. However, VNOI will assist with hotel booking to make logistics easier for you.

Overview

VNOI Cup 2025 will include two online qualification rounds followed by an onsite Final Round.

• The qualification rounds will take place on VNOJ, each lasting 180 minutes and featuring approximately 7 problems of varying difficulty.

• Based on the results, 25 Vietnamese contestants will advance to the Final Round, which will be held onsite in Vietnam.

As in previous years, the competition will be used with multiple subtasks with partial scoring, and penalty time based on incorrect submissions.

Schedule

• Qualification Round 1: June 1 at 20:00 (UTC+7) on VNOJ
• Qualification Round 2: June 15 at 20:00 (UTC+7) on VNOJ
• Final Round (Onsite): July 17, held onsite

⚠️ Each participant must only use one VNOJ account. Anyone who is found using multiple accounts will be disqualified and may be banned from future contests.

Scoring & Ranking

• Scoring: Each problem includes several subtasks with different constraints and point values. You must pass all test cases in a subtask to earn its points.

• Penalty Time: Equals the time of your last score-increasing submission for each problem, plus 5 minutes for each incorrect submission.

• Ranking: Determined by total score (descending). Ties will be broken by lower total penalty time.

Our team

We would like to thank our problem setters and testers for their hard work to ensure quality problems.

• Setters: Kuroni, MofK, darkkcyan, xuanquang1999, thenymphsofdelphi, TranGiaHuy, Namine, vinfat, trungnotchung, huyhasun, KaitoNMH, NguyenDangQuan, lanhf.

• Testers: awoo, shash4321, _Fake4Fun, conqueror_of_tourist, McPqndq, tfg, jeroenodb, eggag32, Adam_GS (will be updated).

Previous Contests and Blogs

For reference purposes, please check out our previous announcements and mirror rounds for VNOI Cup 2024:

• VNOI Cup 2024 – Blog Post

• VNOI Cup 2023 – Blog Post

• VNOI Cup 2024 - Final Mirror

• VNOI Cup 2024 - Round 1 Mirror

• VNOI Cup 2024 - Round 2 Mirror

We're excited to see you in the contest! Good luck, and happy coding!