Hello, Codeforces!

The ICPC World Finals Dhaka will begin on November 10, 2022 at 11:00 (UTC+6). This is the culmination of the 2020-2021 ICPC season, and we have over 130 teams competing for the title of ICPC champion. Please join us on the live broadcast for the main event of the year in competitive programming; commentators will include ecnerwala, SecondThread, Egor, and more! There will also be a live mirror for you to solve the problems alongside the contestants!

Some useful links:

• ICPC Homepage
• World Finals Homepage
• World Finals Schedule
• Live Broadcast
• Live Scoreboard
• Contest Mirror/Judge!

All available broadcasts:

Good luck to all teams competing!

Hello, codeforces.

To unveil the full power of Kotlin and JetBrains tools, as well as their advantages in algorithmic problem-solving, we’ve invited two competitive programming stars to match their skills in solving Kotlin problems on stage at the ICPC World Finals.

Andrew ecnerwala He, one of the top competitive programmers in the world, will compete in a match against Kamil Errichto Debowski, Codeforces "Legendary Grandmaster" and Topcoder "Target." The match will be commentated by none other than Roman elizarov Elizarov, Kotlin Lead Language Designer.

You can join the stream on Kotlin by JetBrains youtube channel at Nov/07/2022 07:17 (Moscow time) and view submissions in the special Codeforces round Ecnerwala vs Errichto Kotlin Match. Only ecnerwala and Errichto can participate in the round, while you will be able to join as spectators.

We will reuse some problems from previous Div3 rounds. We mostly used round #748. And also, one problem was from round #627. A lot of thanks to MikeMirzayanov vovuh and MrPaul_TUser.

Good luck to both participants, and thanks to MikeMirzayanov for the great codeforces platform.

Hello, Codeforces! Or, as we like to say in Romania: Nu îmi amintesc să fi adresat întrebări, Codeforces!

I am glad to finally invite you to participate in CodeTON Round 3 (Div. 1 + Div. 2, Rated, Prizes!), which will start on Nov/06/2022 17:35 (Moscow time). You will be given 8 problems and 2 hours and 30 minutes to solve them. It is greatly recommended to read all the problems, statements are short and straight to the point.

I would like to thank:

• Artyom123 for prodigious coordination.

• AquaMoon, mejiamejia, ugly2333, Ecrade_ for huge help in preparation and authoring one of the tasks.

• errorgorn for being a VIP-tester.

• Lemur95, Gheal, Perpetually_Purple, Everule, IacobTudor, andrei_boaca, lucri, AlperenT, Kuroni, prabowo, lis05, Alon-Tanay, jeroenodb, Juve45, denis2111, Brodicico, Fanurie, huangzirui, satyam343, tfg, Sugar_fan, SlavicG, Vladithur,KrowSavcik, kevinxiehk, sharkycode,Alan, TimDee, Rhodoks, dannyboy20031204,TomiokapEace, Qingyu, lxlxl, ChthollyNotaSeniorious,PinkieRabbit, jerryliuhkg, valeriu, Chenyu_Qiu, jampm, izlyforever, njupt_lyy, RUSH_D_CAT,azureAmarantine, Erkhemkhuu, wh030115,ak2006, dorijanlendvaj, spookywooky, arvindf232, absi2011, AlexLorintz for testing the round and providing invaluable feedback.

• freak93 for morning refreshment.

• MikeMirzayanov for great platforms, codeforces and polygon!

Scoring Distribution: 500-750-1250-1750-2250-2500-3250-3500

The editorial has been published here!

And here are our winners!

• Benq
• zh0ukangyang
• WYZFL
• MagicalFlower
• feecIe6418
• QuietBeautifulThoughts
• p_b_p_b
• conqueror_of_tourist
• jiangly
• tourist

And here is the information from our title sponsor:

Hello, Codeforces!

We, the TON Foundation team, are pleased to support CodeTON Round 3.

The Open Network (TON) is a fully decentralized layer-1 blockchain designed to onboard billions of users to Web3.

Since July, we have been supporting Codeforces as a title sponsor. This round is another way for us to contribute to the development of the community.

The winners of CodeTON Round 3 will receive valuable prizes.

The first 1,023 participants will receive prizes in TON cryptocurrency:

• 1st place: 1,024 TON
• 2–3 places: 512 TON each
• 4–7 places: 256 TON each
• 8–15 places: 128 TON each
• …
• 512–1,023 places: 2 TON each

We wish you good luck at CodeTON Round 3 and hope you enjoy the contest!

Hi Codeforces!

I am pleased to invite you to Adhocforces, Mathforces Codeforces Round #832 (Div. 2), which will take place on Friday, Nov 4, 2022 at 14:35 UTC. You will be given 5 problems and 2 hours to solve them.

The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially in the round.

All problems in this round were prepared by me and CoderAnshu.

I would like to thank:

• antontrygubO_o for coordination of the round.
• ffao, Everule, Andreasyan, koderkushy, nor, AlperenT, the_hyp0cr1t3, Runtime-Terr0r, sp005, 18o3, KingRayuga, Scythe and sus for testing this round and giving really valuable feedback.
• MikeMirzayanov for the amazing Codeforces and Polygon platforms!
• You for participating.

The score distribution will be announced shortly before the round (or earlier).

Good luck and have fun! See you in the standings.

UPD 1:

Scoring distribution: 500 — 1000 — 1250 — 1750 — 2500

UPD 2:

I am flying to dhaka so will post editorials later.

UPD 3:

Congratulations to our winners!

Overall:

1. Um_nik
2. errorgorn
3. turmax
4. OtoriEmu
5. Vercingetorix

Div 2:

1. OtoriEmu
2. Nephren--Ruq--Insania
3. Silviasylvia
4. Gu_Zhou_Suo_Li_Weng
5. googolx

UPD 4: Editorial for A to C has been posted, will post D,E soon.

UPD 5: Editorial for D is posted.

UPD 6: Finally editorial for E is posted.

Halo, Codeforces! 🥰🥰🥰🥰

COMPFEST 14 is happy to invite you to participate in Codeforces Round 831 (Div. 1 + Div. 2) on Oct/29/2022 12:10 (Moscow time). Note the unusual time of the round. The round will be rated for everyone. You will be given 2 hours and 45 minutes to solve 9 problems.

The problems are written by NeoZap, Nyse, Pyqe, and steven.novaryo.

Scoring distribution: 500 — 1000 — 1500 — 1750 — 2000 — 2500 — 2750 — 3000 — 3500

We would like to thank:

• KAN for helping to host the round;
• errorgorn for the based coordination and help with the problem preparation;
• yz_ for helping with the problem preparation;
• MikeMirzayanov, geranazavr555 and KAN for writing the Russian translations;
• Aaeria, AMnu, dorijanlendvaj, eggag32, feecIe6418, fishy15, flamestorm, Gary2005, gisp_zjz, gyh20, MagentaCobra, mejiamejia, oleh1421, powergee101, ppavic, prabowo, Rewinding, tibinyte, tzc_wk, Wailydest for testing the contest and providing us very useful feedback;
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event;
• rama_pang for drinking milk;
• 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. Semoga beruntung dan selamat bersenang-senang!! 💪💪🔥🔥

Edit: round was delayed by 5 mins due to delays of onsite contest.

UPD: contest is over!

Congratulations to our winners!

1. jiangly
2. heno239
3. maroonrk
4. never_giveup
5. Isonan
6. ksun48
7. Um_nik
8. hank55663
9. ugly2333
10. Vercingetorix

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

UPD 2 : Editorial

We are very sorry for the late editorial. We did not anticipate the workload of maintaining an onsite contest, especially since this is the first onsite contest held by our university in three years. We will use this experience to learn and improve our preparation next time.

Finally, we are delighted that the contest ran very well and that many of the contestants are enjoying the contest.

See you next year! 🥰🥰

Hello, Codeforces!

I am happy to invite you to my Codeforces Round 830 (Div. 2) which will be held at Oct/23/2022 13:05 (Moscow time). The round will be rated for all the participants with rating strictly less than 2100 before Oct/23/2022 10:50 (Moscow time).

The tasks were created and prepared by 74TrAkToR. I would like to thank everyone who helped me a lot with round preparation.

• Coordinator Artyom123 for excellent communication and help with preparation.
• Testers gisp_zjz, Pointy, aaaaawa, feecIe6418, nnv-nick, xiaoziya, Ormlis, huangzirui, Chenyu_Qiu, triple__a, gyh20, low_, voventa, tibinyte, Mr.Robot_28, Qingyu, RUSH_D_CAT, physics0523, Lucina, Rhodoks, Tekor, Milesian, Kalashnikov, Lokeo, mejiamejia, TomiokapEace, Chenyu_Qiu, AquaMoon, MagicalFlower for high-quality testing and valuable advices.
• As well as the testers who tested the CheReKOSH Team Olympiad — it was from the problems of this Olympiad that the round was composed: orz, DIvanCode, CAMOBAP31.
• MikeMirzayanov for amazing Codeforces and Polygon platforms.

During the round you will need to solve 5 problems, some of which have subtasks. You will have 2 hours to solve them.

Score distribution will be announced shortly before the round.

We wish you good luck and high rating!

UPD: Score distribution: $$$750-750-(1000-1000)-(1250-1250)-3000$$$

UPD: Editorial

Hi everybody,

This Sunday there will be a XX Moscow Team Olympiad, high school students competition based in Moscow that is an elimination contest for All-Russian Team Olympiad. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Open Olympiad, Moscow Olympiad for Young Students and Metropolises Olympiad (rounds 327, 342, 345, 376, 401, 433, 441, 466, 469, 507, 516, 541, 545, 567, 583, 594, 622, 626, 657, 680, 704, 707, 727, 751, 775, 802).

The round will be held at Oct/23/2022 10:50 (Moscow time) and will last for 2 hours. Note the unusual time of the round. Each division will have 6 problems. The round will be held according to the Codeforces rules and will be rated for both divisions.

Problems of this competition were prepared by Tikhon228, teraqqq, Ormlis, sevlll777, Artyom123, vaaven, Mangooste, Siberian, Alexdat2000, TeaTime, Ziware guided by Tikhon228, grphil and Helen Andreeva.

Thanks to DishonoredRighteous and KAN for the round coordination, statement translation, providing and preparation additional problems, and also thanks for MikeMirzayanov for systems Codeforces and Polygon, which was used to prepare problems of this olympiad.

Also thanks to KLPP and TheOneYouWant for providing and preparation an additional problems that helped to create (I hope) a balanced problem set for the round.

Please note that the ratings will not be recalculated until Codeforces Round 830 (Div. 2), and system testing may be delayed until the end of Codeforces Round 830 (Div. 2).

Good luck everybody!

UPD1: The round was postponed by 15 minutes. Please note the new start time is Oct/23/2022 10:50 (Moscow time).

UPD2: Great thanks to the testers: Um_nik, dorijanlendvaj, errorgorn, vertig1, Makcum888, iakovlev.zakhar, Kon567889, I_love_geom, golikovnik, mejiamejia, Aleks5d, ak2006, jampm, IgorI! As well as the teams testing the main Olympiad: Elderly Passion Fruit (Siberian, alexxela12345, talant) and (maximrufed, omega_alpha, All1gator).

UPD3: Scoring distribution:

Div.2: 500 — 1000 — (750 — 750) — 1250 — 2000 — 2250

Div.1: (500 — 500) — 750 — 1750 — 2000 — 2500 — 3000

UPD4: Winners!

Div. 1:

1. jiangly
2. Rebelz
3. heno239
4. Radewoosh
5. LJC00118

Div. 2:

1. kzyKT
2. Vitinha
3. qtpk
4. Sugar0612
5. bdl

UPD5: Editorial

Our main sponsor invites you to participate in another amazing event in their ecosystem.

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Challenge starts on 23 Oct. at 09:00 UTC and lasts until 18:00 UTC.

The task is to hack 8 smart contracts. Each of these contains a major flaw that allows intentional bypassing of intended logic and stealing of all funds. As soon as the participant figure out the issue they are encouraged to hack the smart contract and get all the Toncoin. The prize will be awarded to the participants, who successfully hack smart contracts, and paid in TON. As soon as the participant figure out the issue they are encouraged to hack the smart contract and transfer all Toncoin from the contract balance (the bounty) to their wallets.

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Here is the TON Hack Challenge checklist to prepare for the contest: 

•  Read the official docs and set up a developer’s environment.
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• Register through the @toncontests_bot.

Hello Codeforces!

On Oct/20/2022 17:35 (Moscow time) Educational Codeforces Round 138 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Adilbek adedalic Dalabaev, Vladimir vovuh Petrov, Ivan BledDest Androsov, Maksim Neon Mescheryakov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

UPD: Editorial is out

Hello Codeforces!

On Oct/17/2022 17:35 (Moscow time) Educational Codeforces Round 137 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Ivan BledDest Androsov, Alex fcspartakm Frolov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

The round is based on the Qualification stage of the Southern and Volga Russian Regional Contest. Thus, we kindly ask its participants to avoid participating in the round.

Good luck to all the participants!

UPD: Editorial is out