Hello!

After we successfully organized TOKI Open 2014 and TOKI Open 2017, we are going to do the similar thing this year. We will open our current IOI Selection Contest to international participants. We call it TOKI Open 2018. TOKI stands for Tim Olimpiade Komputer Indonesia, or Indonesian Computing Olympiad Team in English.

Objectives of us opening this contest include, but not limited to:

• Measure the performance of our IOI trainee compared to other countries' IOI trainee.
• Foster friendship between Indonesia and other IOI participating countries.
• Test Indonesia's scientific committee capability in setting IOI-level problems.
• Test Indonesia's technical committee capability in hosting IOI-level contests.

The contest will have very similar format with IOI, as this contest will be used to select our Top 4 and train our Top 4 for IOI. We expect that the difficulty of the contest is almost the same as IOI. Therefore, this contest is suitable for those who are preparing for IOI. The problems will be available in both Bahasa Indonesia and English.

The rules of TOKI Open 2018 are

• There will be 3 IOI-style problems for each competition day.
• You can only submit at most 50 submissions for a problem.
• You will get full feedback for each submission.
• For each problem, there are several subtasks:
• For each subtask, there are points assigned to it.
• Each subtask contains several test cases.
• You get the points from that subtask if the program passes all the test cases in that subtask.
• The score of a submission is the sum of all the points that you get from completing subtasks.
• The final score for a problem is the maximum of all the submission scores for that problem.
• Unfortunately only C++11 is supported. We will use g++ (Ubuntu 4.8.2-19ubuntu1) 4.8.2 (flags: -std=c++11 -O2 -lm) compiler
• You will only need to implement several functions described in problem statement (i.e. no I/O is needed)
• You can submit clarification requests in either Bahasa Indonesia or English.

The contest will be conducted on TLX Online Judge. You may need to register for a TLX Account if you do not have one. If you have a TLX account, you can login and go to the contest link to register for the contest. There will be two competition days, each having three problems. Each competition day will have two open windows containing the same problemset, so you can participate in either one of the window depending your time preference.

Day 1: Saturday, 26 May 2018

• Window 1: 1.30AM — 6.30AM UTC (8.30AM — 1.30PM Western Indonesian Time). Contest Link.
• Window 2: 12.00PM — 5.00PM UTC (7.00PM — 12.00AM Western Indonesian Time). Contest Link.

Day 2: Monday, 28 May 2018

• Window 1: 1.30AM — 6.30AM UTC (8.30AM — 1.30PM Western Indonesian Time). Contest Link.
• Window 2: 12.00PM — 5.00PM UTC (7.00PM — 12.00AM Western Indonesian Time). Contest Link.

A practice contest to get familiarised with TLX and the problem format is available here. The problems of TOKI Open 2017 are available for upsolving in the problem archive portal.

IMPORTANT: You are not allowed to register on both windows for the same competition day, since they will have the same problemset. If you have registered on a wrong window, you can go to the contest link to unregister.

We invite everyone (especially eligible IOI participants) to participate in this contest. See you at the leaderboard.

UPD1: The day of the second competition day is finalized. It will be on 28 May 2018.

UPD2: The preliminary result of TOKI Open Day 1 is available here. For those who registered in both windows, we only consider the score for the first window (including even if you did not make any submission in the first window).

UPD3 : The post-contest blog post (includes problems repository, full result, etc.) is available here