Hello Codeforces community,

We are excited to invite you to TOKI Indonesian NOI Open Contest 2025 — an online mirror contest for the Indonesian National Olympiad in Informatics 2024. This national olympiad is one of the stages required for our students to qualify to represent Indonesia in the International Olympiad in Informatics (IOI). You may have seen our past open olympiads (2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024) and you can check our past problems here.

The contest is similar to IOI: 2 contest days, each consisting of 3 IOI-style (partial, subtasks) problems to be solved in 5 hours. The schedule is as follows:

• Day 1: 8 October 2025 07:00 — 8 October 2025 23:00 UTC
• Day 2: 9 October 2025 07:00 — 9 October 2025 23:00 UTC

Each contestant can select any 5-hour window within the time range to do the contest for each contest day. The 5-hour timer starts by clicking the "start" button within the contest duration, and no additional time is given if a contestant starts the contest less than 5 hours before the contest ends. The scoreboard will be hidden until the contest has ended.

All contests are now available on TLX. Please register in those contests. You may need to register for a TLX account if you do not have one. For more detailed information and rules, see our official website.

See you on the leaderboard!

UPD. The open contest is not over. You can view the results here. The editorial and upsolving are also available here. Thank you for joining and see you next year!