Hi Codeforces community! :D

We're excited to invite you to TOKI Regular Open Contest (TROC) #6!

Key details:

• Rated
• Contest link: https://tlx.toki.id/contests/troc-6
• Time: 16 June 2019, 19:05 UTC+7
• Style: ICPC-style, 10-minute penalty per wrong submission
• Writers: athin, ayaze
• Duration: 2.5 hours
• Problems: 7
• Allowed languages: C, C++11, Pascal, Java, Python 3

This will be "the last round of TROC" to generate the initial ratings for the contestants.
Everyone can join (combined divisions), and the problemset is expected to be easier than usual.

Please register to the contest, and we hope you will enjoy TROC #6! :D

UPD: Contest is over! Top 5:

1. almogwald
2. KrK
3. AMnu
4. ..vince
5. Pa.Nic

We want to congratulate AMnu to be the first red coder in TLX — TOKI Online Judge! XD
We also want to congratulate Bruteforceman to be the only solver of problem G! XD

Additionally, we would like to thanks prabowo, suhendry, and fushar for testing and proofreading! :D

Editorial is available here (in both Bahasa Indonesia and English).
You can upsolve the problems at https://training.ia-toki.org/problemsets/166/problems.

Thanks for participating and see you on the next chance! :D

Hi Codeforces community! :D

We're excited to invite you to TOKI Regular Open Contest (TROC) #5!

Key details:

• Rated
• Contest link: https://tlx.toki.id/contests/troc-5
• Time: 10 February 2019, 19:05 UTC+7
• Style: ICPC-style, 8-minute penalty per wrong submission
• Writers: ayaze, athin
• Duration: 2 hours
• Problems: 6
• Allowed languages: C, C++11, Pascal, Java, Python 3

The first several rounds of TROCs will be used to generate the initial ratings for the contestants. Everyone can join (combined divisions), and the problemset is expected to be easier than usual.

Please register to the contest, and we hope you will enjoy TROC #5! :D

Nb. We removed the "strict whitespace" rule, hence extra whitespace or no newline at the end won't give you WA anymore, :)

UPD: Contest is over! Top 5:

1. jonathanirvings
2. KrK
3. scanhex
4. wiwitrifai
5. allllekssssa

Editorial will be available here (currently in Bahasa Indonesia only).

You can upsolve the problems at https://training.ia-toki.org/problemsets/152/problems.

Thanks for participating and see you on the next contest! :D

Hi Codeforces community! :D

We're excited to invite you to TOKI Regular Open Contest (TROC) #4!

Key details:

• Rated
• Contest link: https://tlx.toki.id/contests/troc-4
• Time: 30 December 2018, 19:05 UTC+7
• Style: ICPC-style, 8-minute penalty per wrong submission
• Writers: athin, Klungs, jonathanwoenardi, sergiovieri
• Duration: 2 hours
• Problems: 6
• Allowed languages: C, C++11, Pascal, Java, Python 3

The first several rounds of TROCs will be used to generate the initial ratings for the contestants. Everyone can join (combined divisions), and the problemset is expected to be easier than usual.

Please register to the contest, and we hope you will enjoy TROC #4! :D

UPD: Contest is over! Top 5:

1. wiwitrifai
2. -Morass-
3. neko_nyaaaaaaaaaaaaaaaaa
4. wleung_bvg
5. faustaadp

Editorial will be available here (currently in Bahasa Indonesia only). Stay tuned, ;)

You can upsolve the problems at https://training.ia-toki.org/problemsets/151/problems.

Thanks for participating and see you on the next contest! :D

Hi Codeforces community! :D

We're excited to invite you to TOKI Regular Open Contest (TROC) #3!

Key details:

• Rated
• Contest link: https://tlx.toki.id/contests/troc-3
• Time: 18 November 2018, 19:05 UTC+7
• Style: ICPC-style, 8-minute penalty per wrong submission
• Writers: AMnu
• Duration: 2 hours
• Problems: 6
• Allowed languages: C, C++11, Pascal, Java, Python 3

The first several rounds of TROCs will be used to generate the initial ratings for the contestants. Everyone can join (combined divisions), and the problemset is expected to be easier than usual.

Please register to the contest, and we hope you will enjoy TROC #3! :D

UPD: Contest is over! Top 5:

1. prabowo
2. Luqman
3. IgoRamli
4. YogayoG
5. Klungs

Editorial will be available at https://docs.google.com/document/d/1IubDd1DEveZABVmawgmH6zGjbJ5La3DZgkZof3xxxKQ.
Stay tuned, ;)

You can upsolve the problems at https://training.ia-toki.org/problemsets/145/problems.

Thanks for participating and see you on the next contest! :D

Hi Codeforces community! :)

TOKI OSN Open Contest 2018 has ended. Thanks everyone for your participation! :D

There were a total of 96 participants:

• 21 of them achieved a score in the gold cutoff (according to the actual competition of OSN 2018).
• 15 of them achieved a score in the silver cutoff (according to the actual competition of OSN 2018).
• 14 of them achieved a score in the bronze cutoff (according to the actual competition of OSN 2018).

Congratulation to Yehezkiel for winning the contest! The full result of TOKI OSN Open Contest 2018 is available on the official website.

The problems are available for upsolving here (TLX). The problems discussion (editorial) will be written in Bahasa Indonesia only and still in progress. Fear not, we provide you the full repository of OSN 2018 consisting of the solution (including partial solutions), scorer or communicator, and testcase generator here (Github).

We thank everyone who are involved in OSN 2018:

• athin, ayaze, rais.fathin38, FwP, and Yoshiyuki as Scientific Committee
• aguss787+fushar (problem 1C), jonathanwoenardi (problem 1B), ayaze (problem 0D and 2C), athin (problem 0B, 0C, 1A, and 2B), and Scientific Committee (problem 2A) as problem setters
• fushar as writer for problem statements
• indra_vb6, sergiovieri, and ya_ as problem testers
• fushar and nathanchrs as Technical Committee
• ya_ and indra_vb6 as OSN Open Contest Committee

We hope to conduct TOKI OSN Open Contest again next year, with broader audience. If you have any inquiries, please contact scientific@toki.or.id. See you next year! :)

Hi Codeforces community! :D

We're excited to invite you to TOKI OSN Open Contest 2018 -- an online mirror contest for Indonesia national olympiad in informatics. This national olympiad is one of the stages required for our students to qualify to represent Indonesia in the International Olympiad in Informatics (IOI).

The contest is similar to IOI: 2 competition days (+ 1 trial session), each consisting of 3 IOI-style (partial, subtasked) problems to be solved in 5 hours. The schedule is as follows:

• Day 0: 2 July 2018 08:35 — 23:05 UTC (trial session)
• Day 1: 3 July 2018 02:35 — 23:05 UTC
• Day 2: 4 July 2018 02:35 — 23:05 UTC

Each contestant can select any 5-hour window within the time range to do the contest for each competition day. Each contestant may start the contest any time within the time range, by clicking a provided timer button.

All three contests are now available on TLX (https://tlx.toki.id/competition). Please register in those contests. You may need to register for a TLX account if you do not have one already. (Note the new url -- we've got a brand new revamped UI for TLX!)

For more detailed information and rules, see our official website.

See you in the leaderboard! ;)

// P.S.: link to the previous year's contest blogpost can be found here.

UPD: The post-contest information is available here.

We are delighted to announce that TOKI Open Contest Special — April Fools is coming again this year!
Moreover, for the first time, we also open this to non-Indonesian coders! :D

TOKI Open Contest Special — April Fools 2018 consists of "unique" and "oddly satisfying (or annoying?)" problems.
Of course, there is no division of division. And oh, every problem is written in English only right now, :)

You may see last year's problems of TOKI Open Contest Special — April Fools 2017 (only in Indonesian language) or Codeforces April Fools Contest 2017 to grasp the idea of what kind of problems you'll face.

TOKI Open Contest Special — April Fools 2018 is written by Ammar Fathin Sabili (athin) and Alham Fikri Aji (afaji321).

This contest will be held on Sunday, 1 April 2018, 19.00 — 21.30 Western Indonesian Time (UTC+7).
Yes, it will end around 1 hour before Codeforces April Fools Contest 2018! (You may use this for practice, right? :P)

Several details related to the contest:

1. The contest will use ACM-ICPC scoring type and usual classic contest ACM-ICPC rule that is very strict about newline and whitespace.
2. There will be ELEVEN (11) problems with various difficulties but the weight for each problem is the same. The contest duration is 2 hours 30 minutes.
3. Any non-Accepted submission WILL NOT GET ANY PENALTY.
4. The rank will be sorted according to the most number of solves (problems with Accepted verdict). If there are ties, it will be determined by least sum of solving time.
5. The contest will be held on https://competition.ia-toki.org/contests/267. Registration is already opened at the same place. Registering the contest requires a TLX (http://competition.ia-toki.org) account. You may need to register for an account if you don't have one.
6. The allowed programming languages are C, C++11, Pascal, Python 3, and Java 8. However, please note that we do not ensure that every language can solve all the problems on the given time limit.

Are you ready? Great! Wish you all the best, good luck and have fun! :D

UPD 1: We'd like to thanks Agus Sentosa Hermawan (aguss787), Anthony Ng (anthonyhkf), and Muhammad Ayaz Dzulfikar (ayaze) for testing this round.

UPD 2: Congratulations for the winner of TOKI Open Contest Special — April Fools 2018!

1. fuyangzhi

2. pwypeanut

3. Firastic

4. Reiva5

5. chaotic_iak

6. pwild

7. faustaadp

8. Yoshiyuki

9. wijayareynaldo

10. [user:kobusteosousa]

The problems are available at https://training.ia-toki.org/problemsets/109/problems for upsolving. See you at the next TOKI Open Contest! :D

Hello Codeforces Community, TOKI Open Contest is back again! :D

We would like to invite you to participate in this TOKI Open Contest March 2018. TOKI Open Contest is Indonesian (bi-)monthly online programming contest. You may see the January 2018 contest here! :)

Every problem is written in both Bahasa Indonesia and English. The contest will be divided into two divisions: Division 1 and Division 2. It is pretty similar to the divisions in Atcoder (Beginner and Regular). You are free to register in any division (it's extremely OK if you are a Div2 Codeforces user and register to our Division 1 contest)! The expected difficulties of the problems are much the same with Atcoder's contest problems.

TOKI Open Contest March 2018 will be held on Saturday, 24 March 2018, 19.00 — 21.00 Western Indonesian Time (UTC+7). This contest is written by Jonathan Mulyawan Woenardi (jonathanwoenardi); also monitored and supervised by Agus Sentosa Hermawan (aguss787), Ammar Fathin Sabili (athin), Anthony Ng (anthonyhkf), and Muhammad Ayaz Dzulfikar (ayaze).

Several details related to the contest:

1. The contest will use ACM-ICPC scoring type and usual standard contest ACM-ICPC rule that is very strict about newline and whitespace.

2. For each division, there will be FOUR (4) problems with various difficulties but the weight for each problem is the same. The contest duration is 2 hours.

3. The problems are sorted by their expected difficulty from easy to hard. Participants are recommended to read all the problems.

4. Any non-Accepted submission will get 8 minutes penalty but it will only be counted after the respective problem got Accepted.

5. The rank will be sorted according to the most number of solves (problems with Accepted verdict). If there are ties, it will be determined by least (sum of solving time + sum of penalties). The rank will be separated for Division 1 and Division 2.

6. The allowed programming languages are C, C++11, Pascal, Python 3, and Java 8. However, please note that we do not ensure that every language can solve all the problems on the given time limit.

7. The contest will be held on https://competition.ia-toki.org/contests/262 for division 1 and https://competition.ia-toki.org/contests/263 for division 2. Registration is already opened at the same place. Registering the contest requires a TLX (http://competition.ia-toki.org) account. You may need to register for an account if you don't have one.

Wish you all good luck and have fun! See you at the leaderboard! :D

UPD 1 : The contest will be held in less than 24 hours, make sure you are already registered! :D

UPD 2 : The contest is over, thanks for participating the TOKI Open Contest March 2018! :D

This contest has 18 contestants in Division 1 and 33 contestants in Division 2 with at least one submission.

The following are the winner of the TOKI Open Contest March 2018:

Division 1:

1. robinyu solved 3 problems with 161 minutes total penalty.

2. jonathanirvings solved 3 problems with 185 minutes total penalty.

3. Yehezkiel solved 2 problems with 140 minutes total penalty.

Division 2:

1. Reiva5 solved 4 problems with 264 minutes total penalty.

2. halohalo solved 4 problems with 267 minutes total penalty.

3. coderbodoh solved 3 problems with 141 minutes total penalty.

Congratulation to winners! :D

The problems are available at https://training.ia-toki.org/problemsets/108/problems for upsolving. See you at the next TOKI Open Contest! :D

Hello Codeforces Community, TOKI Open Contest is back again! :D

We would like to invite you to participate in this TOKI Open Contest January 2018. TOKI Open Contest is Indonesian monthly online programming contest. It's been a long hiatus since we decided to make this contest international: on February and March 2017! :')

Every problem is written in both Bahasa Indonesia and English. The contest will be divided into two divisions: Division 1 and Division 2. It is pretty similar to the divisions in Atcoder (Beginner and Regular). You are free to register in any division (it's extremely OK if you are a Div2 Codeforces user and register to our Division 1 contest)! The expected difficulties of the problems are much the same with Atcoder's contest problems.

TOKI Open Contest January 2018 will be held on Saturday, 27 January 2018, 19.00 — 21.00 Western Indonesian Time (UTC+7). This contest is written by Kwee Lung Sin (Klungs) and Maximilianus Maria Kolbe (Yoshiyuki); also monitored and supervised by Agus Sentosa Hermawan (aguss787), Ammar Fathin Sabili (athin), and Anthony Ng (anthonyhkf).

Several details related to the contest:

1. The contest will use ACM-ICPC scoring type.

2. For each division, there will be FOUR (4) problems with various difficulties but the weight for each problem is the same. The contest duration is 2 hours.

3. The problems are sorted by their expected difficulty from easy to hard. Participants are recommended to read all the problems.

4. Any non-Accepted submission will get 8 minutes penalty but it will only be counted after the respective problem got Accepted.

5. The rank will be sorted according to the most number of solves (problems with Accepted verdict). If there are ties, it will be determined by least (sum of solving time + sum of penalties). The rank will be separated for Division 1 and Division 2.

6. The allowed programming languages are C, C++11, Pascal, Python 3, and Java 8. However, please note that we do not ensure that every language can solve all the problems on the given time limit.

7. The contest will be held on https://competition.ia-toki.org/contests/253 for division 1 and https://competition.ia-toki.org/contests/254 for division 2. Registration is already opened at the same place. Registering the contest requires a TLX (http://competition.ia-toki.org) account. You may need to register for an account if you don't have one.

Wish you all good luck and have fun! See you at the leaderboard! :)

UPD 1: The contest will be held in less than 20 hours, make sure you are already registered! :D

UPD 2 : The contest is over, thanks for participating the TOKI Open Contest January 2018! :D

This contest has 31 contestants in Division 1 and 41 contestants in Division 2 with at least one submission.

The following are the winner of the TOKI Open Contest January 2018:

Division 1:

1. ayaze solved 4 problems with 164 minutes total penalty.

2. jonathanirvings solved 4 problems with 207 minutes total penalty.

3. wiwitrifai solved 4 problems with 254 minutes total penalty.

Division 2:

1. Reiva5 solved 4 problems with 164 minutes total penalty.

2. farizazmip solved 4 problems with 203 minutes total penalty.

3. ipul23 solved 4 problems with 278 minutes total penalty.

Congratulation to winners! :D

The problems are available at https://training.ia-toki.org/problemsets/106/problems for upsolving. See you at the next TOKI Open Contest! :D

Hello Codeforces Community, TOKI Open Contest is back! :D

We would like to invite you to participate in this TOKI Open Contest March 2017. TOKI Open Contest is our (Indonesian's) monthly/bi-monthly online contest. Starting last month, we had decided to make this contest international! You may see the information of last month contest here. Every problem is written in both Bahasa Indonesia and English.

Starting this month, we divide the contest into two divisions: Division 1 and Division 2. It is pretty similar to the divisions in Codeforces. You are free to register in any division (it's extremely OK if you are a Div2 Codeforces user and register to our Division 1 contest)! The expected difficulties of the problems are much the same with the first four Codeforces' contest problems (A to D).

TOKI Open Contest March 2017 will be held on Saturday, 25 March 2017, 19.00 — 21.00 Western Indonesian Time (UTC+7). This contest is written by Agus Sentosa Hermawan (aguss787), Ammar Fathin Sabili (athin), Anthony Ng (anthonyhkf), and Muhammad Ayaz Dzulfikar (ayaze).

Several details related to the contest:

1. The contest will use ACM-ICPC scoring type.

2. For each division, there will be FOUR (4) problems with various difficulties but the weight for each problem is the same. The contest time is 2 hours.

3. The problems are sorted by their expected difficulty from easy to hard. Participants are recommended to read all the problems.

4. Any non-Accepted submission will get 8 minutes penalty (but the penalty will only be counted after the respective problem got Accepted).

5. The rank will be sorted according to the most number of solves (problems with Accepted verdict). If there are ties, it will be determined by least (sum of solving time + sum of penalty). The rank will be different for Division 1 and Division 2.

6. The allowed programming languages are C, C++11, Pascal, Python 3, and Java 8. However, please note that we do not ensure that every language can solve all the problems on the given time limit.

7. The contest will be held on https://competition.ia-toki.org/contests/170 for division 1 and https://competition.ia-toki.org/contests/171 for division 2. Registration is already opened at the same place. Registering the contest requires a TLX (http://competition.ia-toki.org) account. You may need to register for an account if you don't have one.

Good luck and have fun! See you at the leaderboard! :)

UPD 1 : The contest will be held in less than 24 hours, make sure you are already registered! :D

UPD 2 : The contest is over, thanks for participating the TOKI Open Contest March 2017! :D

This contest has 27 contestants in Division 1 and 67 contestants in Division 2 with at least one submission.

The following are the winner of the TOKI Open Contest March 2017:

Division 1:

1. jonathanirvings solved 3 problems with 142 minutes total penalty.

2. pwypeanut solved 3 problems with 192 minutes total penalty.

3. wiwitrifai solved 3 problems with 295 minutes total penalty.

Division 2:

1. [numberking] solved 3 problems with 278 minutes total penalty.

2. [yogahmad] solved 2 problems with 19 minutes total penalty.

3. [kevlee] solved 2 problems with 44 minutes total penalty.

Congratulation to winners! :D

The problems are available at https://training.ia-toki.org/problemsets/82/problems for upsolving. See you at the next TOKI Open Contest! :D

Err.. I'm sorry for Tebak_Siapa_Aku, the official announcement is late, but here is it, just a couple of minutes after you posted the unofficial here :')

Hello everyone! :D

Indonesia will hold 2016 National Olympiad in Informatics this week (May 16th — May 18th 2015) in Palembang, Indonesia. It is a competition for Indonesian high school students as one of the preliminary round of Indonesian IOI selection. The contest consists of three separated contests:

• Day 0 (Practice Contest): Monday, May 16th 14.00 — 17.00 (UTC +7)
• Day 1: Tuesday, May 17th 08.30 — 13.30 (UTC +7)
• Day 2: Wednesday, May 18th 08.30 — 13.30 (UTC +7)

And this is the second year for Indonesia (last year event : here) to invite everyone around the world to try solving the problems by participating the Open Contest! The Open Contest will be held in https://competition.ia-toki.org/.

There will be three different contests, one for each day. You may participate them separately (e.g. only participate in Day 1 and Day 2, but not in Day 0), but we expect you to join them all. Unlike last year, they are not virtual contests. The Open Contest will start after an hour from the real contest. Here are the schedule and details for the Open Contest:

• Day 0 (Practice Contest): Monday, May 16th 15.30 — 24.00 (UTC +7). Register here.
• Day 1: Tuesday, May 17th 09.30 — 14.30 (UTC +7). Register here.
• Day 2: Wednesday, May 18th 09.30 — 14.30 (UTC +7). Register here.

Several notes:

• No medals/certificates will be awarded to Open Contest participants.
• Each contest will have 3 IOI-styled problems.
• Problem statements will be provided in English and Indonesia.
• There is a submission limit of 30 for each problem.

We hope you will find many interesting problems here. Good luck and thanks for your participation! :D

UPD Open OSN is delayed for 30 minutes, it will start on 10.00.

UPD Registrations are open until the start of each contests, except for Day 0 (you can register at anytime before the end of the contest).

UPD The results are out! You can access Open OSN results here.

Thanks for all people who participated in this contest! We wish you had a great problemset and experiences, we are looking forward to your participation next year! :D

Indonesian National Olympiad in Informatics Committee