Hello, Codeforces!

We're excited to invite you to TLX Regular Open Contest #38!

Key details:

• Contest links: TLX

• Time: 7th Sept 2024, 14:05 UTC

• Writer: Pyqe

• Duration: 2 hours

• Problems: 7

• Scoring distribution: 100 — 200 — 300 — 450 — 450 — 550 — 650

I would likke to thank:

• yz_ aand steven.novaryo for the based coordinationn!
• aufannn, kimmoqt, Nevll, MetalPower for testting the problems and giiving based feedback.
• fushar for the based TLX pplatform.

Please register for the contest and I encourage you to reaad all problems!

UPD: Added scoring ditribution!

Congratulations to the top 5:

1. hos.lyric

2. kotatsugame

3. Rubikun

4. asdsasd

5. Benq

Congratulations to our first solvers:

• A: Rubikun

• B: Benq

• C: potato167

• D: Benq

• E: Benq

• F: kotatsugame

• G: hos.lyric

You can upsolve the problems here. Editorials are available in the upsolve link!

There is a hidden theme in this contest. Did you find it?

Thank you for participating and making Kantipa happy! I hope you all enjoyed my MS Paint drawings! See you on the next contest!

Hello Codeforces community,

We are excited to invite you to TOKI Indonesian NOI Open Contest 2024 — 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) 2025. You may have seen our past open olympiads (2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023), and you can check our past problems here.

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

• Day 0: 27 August 2024 11:00 — 28 August 2023 06:00 UTC (trial session)
• Day 1: 28 August 2024 07:00 — 29 August 2023 06:00 UTC
• Day 2: 29 August 2024 07:00 — 30 August 2023 06:00 UTC

Each contestant can select any 5-hour window (2-hour for Day 0) 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 three 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 windows are over!

You can view the scoreboard for the open contest here. Upsolving and the editorials will be available once the final results of the official contest is announced.

2A. Goals of Victory

Author: nandonathaniel
Developer: nandonathaniel

2B/1A. Helmets in Night Light

Author: ArvinCiu
Developer: gansixeneh

2C. Joyboard

Author: Pyqe
Developer: gansixeneh

2D/1B. Effects of Anti Pimples

Author: Pyqe
Developer: Pyqe

2E/1C. Autosynthesis

Author: Pyqe
Developer: Pyqe

2F/1D. Lexichromatography

Author: Pyqe
Developer: Pyqe

2G/1E. Ball-Stackable

Author: Pyqe
Developer: Pyqe

1F. Indefinite Clownfish

Author: Pyqe
Developer: Pyqe

1G. Clubstep

Author: Pyqe
Developer: Pyqe

Sugeng enjing, Codeforces! 🥰🥰🥰🥰

COMPFEST 15 is happy to invite you to participate in Codeforces Round 902 (Div. 1, based on COMPFEST 15 - Final Round) and Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round) on Oct/08/2023 12:05 (Moscow time). Both rounds will be rated. You will be given 2 hours and 30 minutes to solve 7 problems.

Note the unusual time of the round.

The problems are written by ArvinCiu, Pyqe, and nandonathaniel.

We would like to thank:

• KAN for helping to host the round;
• errorgorn and ScarletS for the based coordination;
• gansixeneh and nandonathaniel for helping with the problem preparation;
• ArvinCiu, CyberSleeper, and Edbert.H for providing alternate solutions in the early stages;
• Alexdat2000 for writing the Russian translations;
• Aaeria, AMnu, Berted, BucketPotato, buffering, Drew_, dorijanlendvaj, eggag32, Elben85, emorgan, faustaadp, ffao, fishy15, flamestorm, gamegame, hocky, Insta-x, jdurie, joelgun14, KerakTelor, Marky, Murinh0, nvmdava, yz_, Owmicron, prvocislo, PurpleCrayon, rama_pang, TakeMe, sahil_k, user202729_, Vladithur, WHCPP, and ZeroScar for testing the contest and providing us very useful feedback;
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event;
• MikeMirzayanov for the amazing Codeforces and Polygon platform!

COMPFEST itself is an annual event hosted by Universitas Indonesia. It is the largest student-run IT event in Indonesia and competitive programming contest is one of the competitions hosted.

We hope you will enjoy and have fun in the contest. Muga-muga beja lan isa entuk biji apik!! 💪💪🔥🔥

UPD: Scoring distribution

• Div. 1: 500 — 1000 — 1250 — 1750 — 2250 — 2750 — 3250
• Div. 2: 500 — 1000 — 1500 — 2000 — 2500 — 2750 — 3000

UPD2: Contest is over!

Congratulations to our winners!

Congratulations for our first solvers:

We will try to post the editorials as soon as possible. Please stay tuned!

UPD3: Editorial

On behalf of the COMPFEST committees, we are glad that our Codeforces Round ran quite smoothly and we hope that you all enjoyed our problems. See you next year! 😍😍

1866A. Ambitious Kid

Author: Pyqe
Developer: nandonathaniel

1866B. Battling with Numbers

Author: KokiCoder
Developer: nandonathaniel

1866C. Completely Searching for Inversions

Author: Pyqe
Developer: gansixeneh

1866D. Digital Wallet

Author: CyberSleeper
Developer: CyberSleeper

1866E. Elevators of Tamem

Author: FreeJinG
Developer: Pyqe

1866F. Freak Joker Process

Author: nandonathaniel
Developer: Pyqe

1866G. Grouped Carriages

Author: ArvinCiu
Developer: ArvinCiu

1866H. Happy Sets

Author: Edbert.H
Developer: Edbert.H

1866I. Imagination Castle

Author: CyberSleeper
Developer: CyberSleeper

1866J. Jackets and Packets

Author: asteriskzie
Developer: Pyqe

1866K. Keen Tree Calculation

Author: nandonathaniel
Developer: Pyqe

1866L. Lihmuf Balling

Author: gansixeneh
Developer: gansixeneh

1866M. Mighty Rock Tower

Author: ArvinCiu
Developer: ArvinCiu

Hello, Codeforces! 😍😍

We are happy to invite you to participate in COMPFEST 15 Preliminary Online Mirror (Unrated, ICPC Rules, Teams Preferred) on . COMPFEST is a national ICPC-style contest for university students in Indonesia.

The problems are written and prepared by ArvinCiu, asteriskzie, CyberSleeper, Edbert.H, FreeJinG, gansixeneh, KokiCoder, nandonathaniel, and Pyqe.

We would also like to thank:

• KAN for helping to host the mirror round;
• AMnu, (KerakTelor, Owmicron, ZeroScar), (yz_, Berted, Elben85), errorgorn, Drew_, and joelgun14 for testing the contest and providing us very useful feedback;
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event;
• fushar for the Judgels platform used in the official contest; and finally
• MikeMirzayanov for the amazing Codeforces and Polygon platform!

The contest will last for 5 hours and consist of 13 problems. The statements will only be available in English. While it is preferred to participate in a team, individual participation is also allowed.

COMPFEST itself is an annual event hosted by Universitas Indonesia. It is the largest student-run IT event in Indonesia and competitive programming contest is one of the competitions hosted.

We hope you will enjoy and have fun in the contest. Good luck! 🔥🔥🔥🔥

UPD: Contest is over!

Congratulations for our first solvers!

• A: arvindf232
• B: maspy
• C: (Speed Star: noimi, SSRS_)
• D: (ITMO PTU: dimss, Kirkon, andreyDagger)
• E: Morphymorphymorphy
• F: (JoesSR fan club: red-stone, LXH-cat, wsyear)
• G: (DELIAIR: sapphire15, tokusakurai, torisasami)
• H: (Hamood? Hamood!: qiuzx, njwrz, sjcsjcsjc)
• I: (absinthe: user202729_, nvmdava, rama_pang)
• J: (Beyond Three Wolves: Yapparimurideshita, Kevin114514, Atomic-Jellyfish)
• K: (致远星: AlternatingCurrent, PersistentLife, grass8sheep)
• L: (Team named after Elena Engurazova: otsekai, oversolver, Blinov_Artemii)
• M: hos.lyric

Editorial is available here!

Hello Codeforces community,

We are excited to invite you to TOKI Indonesian NOI Open Contest 2023 — an online mirror contest for the Indonesian 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). You may have seen our past open olympiads (2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022), and you can check our past problems here.

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

• Day 0: 28 August 2023 11:00 — 29 August 2023 06:00 UTC (trial session)
• Day 1: 29 August 2023 07:00 — 30 August 2023 06:00 UTC
• Day 2: 30 August 2023 07:00 — 1 September 2023 06:00 UTC (2 days)

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 at any time within the time range by clicking the "start" button. There will be no additional time 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.

We are aware that the contest days overlap with IOI 2023; unfortunately, we cannot change the dates.

All three 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 official contest has ended, thanks for your participation!

The result of the open contest can be found on our website.

You can upsolve the problems here. The official editorials are available in the upsolve link

We thank everyone who is involved:

• Scientific Committee: hocky, Mushtofa, yz_, Pyqe, rama_pang
• Technical Committee: aguss787, AVM.Martin, fushar, siplusplus, vioalbert
• Organising Committee: Drew_, kalEl2001
• Authors: ayaze, yz_, prabowo, Pyqe, rama_pang
• Tester: ArvinCiu, faustaadp, jt3698

We hope we can conduct the open OI again, and see you next year!

Dear Codeforces community,

We are excited to invite you to TLX Regular Open Contest #32!

Key details:

• Contest URL: TLX
• Time: 7th May 2023, 12:05 UTC
• Writer: Pyqe
• Duration: 120 minutes
• Problems: 7
• Scoring distribution: 100 — 200 — 300 — 400 — 500 — 600 — 700

Many thanks to:

• steven.novaryo and yz_ for their help in coordinating the round and in preparing the problem components. 😂👌💯
• AMnu and Drew_ for testing the contest.
• fushar for the amazing TLX platform.

Please register to the contest and we hope you will enjoy TROC #32! 🔥🔥🔥🔥

UPD: The round has been delayed by 15 minutes due to technical difficulties. We are sorry for the inconvenience.

Congratulations to the top 5:

1. errorgorn

2. kotatsugame

3. potato167

4. heno239

5. hitonanode

Congratulations to our first solvers:

• A: SSRS_

• B: SSRS_

• C: hos.lyric

• D: BucketPotato

• E: Kinon

• F: errorgorn

• G: errorgorn

You can upsolve the problem here. Editorial is available in the upsolve link!

Thank you for participating and see you on the next contest!

1740A. Factorise N+M

Author: Pyqe
Developer: Pyqe

1740B. Jumbo Extra Cheese 2

Author: Pyqe
Developer: errorgorn, Pyqe

1740C. Bricks and Bags

Author: Pyqe
Developer: Pyqe

1740D. Knowledge Cards

Author: Nyse
Developer: steven.novaryo

1740E. Hanging Hearts

Author: Pyqe
Developer: yz_

1740F. Conditional Mix

Author: Pyqe
Developer: errorgorn

1740G. Dangerous Laser Power

Author: Pyqe
Developer: Pyqe

1740H. MEX Tree Manipulation

Author: steven.novaryo
Developer: steven.novaryo, Pyqe

1740I. Arranging Crystal Balls

Author: NeoZap
Developer: errorgorn, Pyqe

Dear Codeforces community,

We are excited to invite you to TOKI Regular Open Contest #27 (based on COMPFEST 14)! For those of you who don't know, COMPFEST is a national contest for university students in Indonesia.

Key details:

• Contest link: TLX
• Time: 25th September 2022, 12:05 UTC
• Writer: nandonathaniel Nyse Pyqe TakeMe
• Duration: 2 hours 20 minutes
• Problems: 8
• Scoring distribution: 100 — 200 — 350 — 500 — 500 — 500 — 700 — 700

Many thanks to:

• steven.novaryo for the dedication and effort in COMPFEST 14 and TROC 27.
• NeoZap yz_ for helping with problem preparation.
• AMnu bry_rp bukanYohandi david.alexander01 Drew_ errorgorn for testing the problems and giving feedback.
• fushar for the TLX platform.
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event.

COMPFEST itself is an annual event hosted by Universitas Indonesia. It is the largest student-run IT event in Indonesia and competitive programming contest is one of the competitions hosted.

Please register and we hope you will enjoy the contest!

UPD: contest is over!

Congratulations to our top 5:

1. heno239
2. gyh20
3. hitonanode
4. SSRS_
5. tatyam

Congratulations to our first solvers:

• A. tabr
• B. tabr
• C. SSRS_
• D. heno239
• E. tabr
• F. SSRS_
• G. SSRS_
• H. heno239

You can upsolve the problems here.

Thank you for participating!

UPD 2: editorial is available in the upsolve link.

1725A. Accumulation of Dominoes

Author: Pyqe
Developer: nandonathaniel
Editorialist: Pyqe

1725B. Basketball Together

Author: FerdiHS
Developer: muhammadhasan01
Editorialist: Pyqe

1725C. Circular Mirror

Author: Pyqe
Developer: steven.novaryo
Editorialist: steven.novaryo

1725D. Deducing Sortability

Author: Pyqe
Developer: TakeMe, Pyqe
Editorialist: Pyqe

1725E. Electrical Efficiency

Author: steven.novaryo
Developer: steven.novaryo
Editorialist: rama_pang

1725F. Field Photography

Author: Pyqe
Developer: Pyqe
Editorialist: Pyqe

1725G. Garage

Author: Nyse
Developer: Nyse
Editorialist: Pyqe

1725H. Hot Black Hot White

Author: Pyqe
Developer: steven.novaryo
Editorialist: steven.novaryo

1725I. Imitating the Key Tree

Author: Pyqe
Developer: Pyqe
Editorialist: Pyqe

1725J. Journey

Author: gansixeneh
Developer: gansixeneh, steven.novaryo
Editorialist: rama_pang

1725K. Kingdom of Criticism

Author: Pyqe
Developer: Pyqe
Editorialist: rama_pang

1725L. Lemper Cooking Competition

Author: Pyqe
Developer: steven.novaryo
Editorialist: rama_pang

1725M. Moving Both Hands

Author: Pyqe
Developer: Pyqe
Editorialist: rama_pang

Dear Codeforces community,

We are excited to invite you to TOKI Regular Open Contest #21! 👊😎

Key details:

• Contest link: TLX
• Time: 14th April 2021, 13:05 UTC
• Writer: Pyqe
• Duration: 2 hours
• Problems: 7

Scoring distribution: 100 — 200 — 300 — 500 — 500 — 600 — 800

Many thanks to:

• prabowo for coordinating the contest. 😂👌
• hocky for helping with problem preparation. 💯
• JulianFernando and AMnu for testing the problems.
• fushar for the TLX platform.

Please register and we hope you will enjoy the contest! 🔥🔥🔥🔥

UPD: Please note there is a change in the contest timing.

UPD2: Contest is over!

Congratulations to our top 5:

1. maroonrk
2. neal
3. hitonanode
4. noimi
5. nuip

Congratulations to our first solvers:

• A: noimi
• B: hitonanode
• C: Geothermal
• D: hitonanode
• E: hitonanode
• F: Nyaan
• G: maroonrk

You can upsolve the problems here.

Editorial is available in the upsolve link.

Thank you for participating and see you on the next contest! 😭👍

The problems in this contest follows a theme. Can you guess the theme?