Hello, Codeforces!

After years of hard work, we are euphoric to invite you to participate in Codeforces Round 1077 (Div. 1) and Codeforces Round 1077 (Div. 2), which will be held at Jan/29/2026 17:35 (Moscow time). For both divisions, you will be given $$$7$$$ problems and $$$3$$$ hours to solve them. For at least one of the divisions, one of the problems will be divided into two subtasks.

The problems are invented and prepared by Bronya_H, Error_Yuan, StarSilk, Tobo, __baozii__ and me.

We would like to thank:

• SSerxhs for his Superb, Stellar, Extraordinary, Reliable, Xcellent, Helpful and Supportive coordination.
• Alexdat2000 for Russian translations.
• zeemanz and bookcat for providing some ideas that were not ultimately used.
• cry for inventing a basement of infinite capacity to imprison cheaters.
• errorgorn, tiger2005, EnofTaiPeople, and dXqwq for black opal testing.
• geospiza, Aging1986, Sugar_fan, Duck_sajin, qkm66666, AYTDD, Fantasy_Blue, Intellegent, SATSKY_2025target_LGM, _istil, wangmarui, rucaco, fallleaves01, permutation, nifeshe, and A_G for ruby testing.
• Proof_by_QED, sh1ziku, 0x3F, K_tian, aori., sszcdjr, hxu10, CirnoNine, and chennie for topaz testing.
• fatalerror, Fusu, -WIDA-, shendeliliang, and Liang_SYEA for amethyst testing.
• Kato_Shoko, TEYL, clearlove13, Non-origination, chromate00, fr200110217102, and XiaoXia for sapphire testing.
• imhighshou and Clclclcl for aquamarine testing.
• MikeMirzayanov for his obsidian Codeforces and Polygon platform.

The score distribution will be announced later, along with my crossdress cosplay photograph.

We sincerely hope you can enjoy the problems. Good luck and see you on the field !

Hello, Codeforces!

We are glad and excited to invite you to take part in Codeforces Round 1076 (Div. 3), which will take place on Jan/25/2026 17:35 (Moscow time). You will be given 2 hours and 15 minutes to solve 7-8 probmles. At least one problem will be interactive, so we highly recommend to read guide for interactive problems before the contest.

The round will be hosted by the rules of educational rounds (extended ICPC). Thus, all solutions will be judged on preliminary tests during the round, and after the round, there will be a 12-hour phase of open hacks. After the open hack phase, all accepted solutions will be rejudged on successful hacks.

As a reminder, only trusted participants of the third division will be included in the official standings table. This is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

• take part in (and solve at least one problem in) at least five rated rounds
• and not have had a rating of 1900 or higher at any moment in time.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

Problems were authored by KluydQ, YF_YUSUF, Wansur, Mendeke.

We would like to give special thanks to:

• Vladosiya and soullless for the great coordination and chance to host this contest.
• Wansur, k1r1t0, Arpa, Aldk, SorahISA, QazLon, itz_pabloo, YF_YUSUF, Daki-sa, Yessimkhan, Arkanefury, hamburger46, gbula, China001, Dobri_oke, Idam, wadibay, Darko, uwbt17, raiywbek, CLown1331 for their time and effort in testing.
• MikeMirzayanov and KAN for the great Codeforces and Polygon platforms.

UPD: Editorial is here

Hello, Codeforces!

We are excited and pleased to announce that Codeforces Round 1075 (Div. 2) will be held on Jan/23/2026 17:35 (Moscow time). This round will be rated for all participants with rating below $$$2100$$$. You will be given $$$2$$$ hours to solve $$$6$$$ problems and some problems will be divided into subtasks.

The round is based on the Sharygin International Geometry Olympiad All problems were authored and prepared by yanb0, furt1ve and me.

We would like to express our special thanks to:

• Akulyat for coordinating the round and assistance in preparing problems;
• the testers: Wansur, __baozii__, k1r1t0, Mark_Pr, _istil, OG_Matveychick1, TimDee, zhenja, abs0lute, princeee, NotDWT, Sokol080808, machine_solution, Pobe, madlogic, wuhudsm, pattern-seeker, dvb1r, VitaliiV, penwick, sanya37y, itz_pabloo, Morselllprimo, AK_15, Golden_Square, Norman165, arsen1y, graphs_enjoyer, tih-a, emirhanbanan, ak1ko, s97b, thereverberation, bibiq for their time and effort in testing the problems;
• MikeMirzayanov and KAN for the great platforms.

The score distribution is below.

$$$500-1000-(1250+750)-(2000+750)-2500-3250$$$

GLHF!

UPD1 The round is over, thank you for participation.

UPD2 Editorial

UPD3 Winners and First to solve

Div2

Div1 + Div2

First to solve

The Registration for the 50th Petrozavodsk Programming Camp is open.

THE CAMP WILL BE HELD ONLINE from January 29 to February 06, 2026.

For teams from the EAEU, offline participation is possible; details are in the information letter.

Teams of up to 3 members are invited to join

The level of contests: for participants of the semi-finals and finals of the ICPC World Championship

The training Camp schedule consists of 8 contests and 1 day off between them, preliminary schedule: camp.icpc.petrsu.ru/2026w/schedule

For each contest, a problem analysis will be broadcast in English.

The registration fee for participants from the EAEU countries is 12200 / 13420 / 24400 rubles per participant (depends on meal inclusion).
The registration fee for participants from other countries is $165 per participant.

To register, the team coach should write a letter to the organizers.
After agreement, each team member must go through individual registration on the site of the Camp.

Contact Information

• Contact the organizers: [email protected]
  
• Website: camp.icpc.petrsu.ru
  
• Group in VK: vk.com/camp_acm_petrsu
  

Hello Codeforces!

I am delighted to invite you to the first Div. 4 round of the year: Codeforces Round 1074 (Div. 4)! The round is scheduled for Jan/18/2026 17:35 (Moscow time). You will be given 7 — 8 problems to solve (all authored by me), and 2 hours and 15 minutes to solve them.

The format of the event will be identical to Div. 3 rounds:

• ICPC rules with a penalty of 10 minutes for an incorrect submission.

• 12-hour phase of open hacks after the end of the round (hacks do not give additional points).

• After the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings will be recalculated.

Only trusted participants of the fourth division will be shown in the official standings. To be a trusted participant, you must:

• have participated in at least 5 rated rounds where you have solved at least one problem.

• have a rating less than 1400.

Regardless of if you are a trusted participant or not, this round will be rated for you if you

• have a rating of less than 1400 or are unrated.

• do not select the "Register as unrated" option when registering for the contest.

Participants who are rated 1400+ are not allowed to create a new account for the purpose of competing officially. We encourage you to take part unofficially.

We would like to remind all participants about the rule against using artificial intelligence tools during the contest. Violators will be sent to cry's basement; we spent a long time expanding it so we could host this round, and we sincerely hope that it won't be filled back up again.

I would like to thank:

• cry for being an incredible coordinator, and for giving me a chance to write this contest.

• Vladosiya for translating the problems into Russian.

• cduckling for looking over the initial problemset before I officially proposed it.

• Our red testers: __baozii__, Intellegent

• Our golden testers: Arpa, -firefly-, AksLolCoding, Edeeva, Friedrich, omsincoconut, Proof_by_QED, temporary1

• Our purple testers: macaquedev, pop, tin.le2, wuhudsm

• Our blue testers: apollo07, Argentum47, Eikyu, Ermiooo159, expertaq, Jteh, ritam1234, simplelife, SpyrosAliv, susvent, Vladosiya

• Our cyan tester: anandswaroop191

• Our gray testers: DraxLab, piman51277

• Our unrated tester: qdread

• MikeMirzayanov for creating Codeforces, Polygon, and testlib.h.

• You, for participating!

I wish you all the best of luck in this competition, and I hope you enjoy the problems!

EDITORIAL.

Hello Codeforces,

After decades of hard work and several quality reviews from independent third parties, I'm delighted to invite you to participate in Codeforces Round 1073 (Div. 1), and, if you really want to, Codeforces Round 1073 (Div. 2), which will both held on Jan/17/2026 17:35 (Moscow time).

In each division, you will be given $$$7$$$ problems and $$$3$$$ hours to solve them, one of which will be divided into subtasks. Problems were mainly authored by me, nifeshe, with help from nika-skybytska and satyam343. Only $$$6$$$ or $$$7$$$ problems will not be interactive in each division, so please make sure to read the guide for interactive problems before the contest.

In related news, we’ve already been awarded the Nobel Peace Prize for this round, for achieving a level of problem quality so universally accepted that all global conflicts have been resolved.

I would like to thank the following people for making the contest possible:

• satyam343 for outstanding coordination and helping with problem ideas/preparation.
• Um_nik for preliminary reviewing the round.
• Sana for being the most helpful tester I've ever seen.
• EvenImage, Geothermal, A_G, sammyuri, _istil, Intellegent, catgirl, Dragos, weirdflexbutok, Hori, samsoom, whiitex for VIP testing.
• The rest of our testers: LipArcanjo, Adam_GS, __baozii__, jiazhichen844, maomao90, IceKnight1093, wangmarui, caterpillow, -firefly-, arvindr9, djm03178, omsincoconut, CatsAreCool, reirugan, conjectureguy, SpyrosAliv, chromate00, Non-origination, beaten_by_ai.
• Alexdat2000 for translating the problems to Russian.
• MikeMirzayanov and KAN for the Codeforces and Polygon platforms.
• And You for participating!

The score distribution is below.

Div. 1:

Div. 2:

Unlike other rounds, this one will only be held once, so I sincerely hope you will not skip the round and enjoy all of the problems.

UPD 1 The hacks are disabled for problems A — D2 in Div 2, and for problems A — B2 in Div 1. We have final tests consisting of pretests and hacks for all problems.

UPD 2 Editorial

UPD 3

Congratulations to the winners.

Div. 1:

1. Petr
2. strapple
3. jiangly
4. tourist
5. Radewoosh

Div. 2 (subject to change):

1. LHNB
2. xoxoKitty
3. EchidnaTea
4. AuroraUwU
5. t1e1

First solves:

Div. 1:
A. 00:02:15 by TKT_YI
B1. 00:08:23 by Petr
B2. 00:14:54 by strapple
C. 00:35:39 by jiangly
D. 00:21:27 by PCTprobability
E. 01:42:55 by XVIII
F. 02:53:16 by olmrgcsi
G. 01:34:40 by rainboy

Div. 2 (subject to change):
A. 00:01:21 by akshW
B. 00:05:49 by khushicodes03
C. 00:10:28 by ansh91627
D1. 00:12:47 by CoderMeow
D2. 00:18:11 by sks4401
E. 00:54:52 by crimson_leaf
F. 00:47:03 by shobhitgagrani.coding33
G. 02:54:37 by dooglius

Hello, Codeforces!

The TG channel team @KogutIvanTutoring is pleased to invite you to participate in the first Div. 3 round of this year — Codeforces Round 1072 (Div. 3) on Jan/12/2026 17:35 (Moscow time). This round will feature 6-7 problems selected in difficulty to create an interesting competition for participants with ratings up to 1600. However, anyone with a rating of 1600 or higher can register for the round out of competition.

The round will follow the rules of educational rounds. Thus, during the round, the problems will be tested on preliminary tests, and after the round, there will be a 12-hour phase of open hacking. After this phase, all successful attempts will be retested on successful hacks. We have tried to create decent tests — just like you, we will be disappointed if many solutions fail after the contest ends.

You will be offered 6-7 problems and 2 hours 15 minutes to solve them.

The penalty for an incorrect attempt in this round will be 10 minutes.

We remind you that only reliable participants of the third division will be included in the official results table. As stated in the link — this is a necessary measure to combat unsportsmanlike behavior. To qualify as a reliable participant of the third division, you must:

• participate in at least five rated rounds (and solve at least one problem in each of them)
• not have a rating point of 1900 or higher.

Regardless of whether you are a reliable participant of the third division or not, if your rating is below 1600, the round will be rated for you.

The problems were conceived and prepared by part of our team: fstilus, Friendiks, gravitsapa, EzikBro, Boodoochai

Also, a big thank you to:

• MikeMirzayanov for the Polygon and Codeforces systems.

• Vladosiya for coordinating the round.

• misha.arkhipov, Escapisst, feblokas, lewc, mlovbnee, Yassia, YamOCHca, -_TIMOFEY_-, _liravel_, Gmacem, vintermach, margothequeen, itz_pabloo, sivukhin, Merkurev, the_dragon_emperor, Cyber, MariamH, Arpa, Marckess for testing of the round.

Good luck to everyone!

UPD. Editorial is out!

Happy new year, Codeforces!

We are glad to invite you to take part in Hello 2026, which will start on Jan/07/2026 17:35 (Moscow time). You will be given 9 problems and 3 hours to solve them. At least one problem will be interactive, so please make sure to read the guide for interactive problems before the contest. This round is open and rated for everyone.

Problems are authored by wangmarui, Gold14526, Hoks_, Neil_Qian, Network_Error, jiazhichen844 and xvchongyv.

We would like to thank:

• Um_nik for pre-reviewing the round.
• Proof_by_QED for his wonderful coordination.
• Alexdat2000 for Russian translation.
• Geothermal, StarSilk, and Dominater069 for nutella testing.
• Mindeveloped, ETO_leader, nldr, max0810, A_G, _istil, ian_HLX, nifeshe, paulzrm, sammyuri, catgirl and Intellegent for red testing.
• cuteSubtask, LucaLucaM, cry, Genius_Star_rgw, Friedrich, incra, lkrqwq, LaDeX, pichax, shiny_shine, efishel, Edeeva, Register, AksLolCoding, Watersphere, Lilypad, tzl_Dedicatus545, Caylex and waauto for yellow testing.
• NATO, Cfz_qwq, MagentaCobra, gza, wuhudsm, madlogic and Heartquake for purple testing.
• tybbs, larush, pianapolataa, Terminator-XII, hollis_yang, Nukumizu-Anna, shengxuanyi, chromate00 and cby_ for blue testing.
• wizardMarshall, Solwek, sztcodeforces and lottle1212 for cyan testing.
• yaotianhao0906, lovelyfish and YSY_ for green testing.
• chenzhishuo2012 and doraimota for gray testing.
• Lynette_D for unrated testing.
• MikeMirzayanov and KAN for the great Codeforces and Polygon platforms.
• You for participating in this round.

Score Distribution: $$$500 - 1000 - 1500 - (1000 - 2000) - 2250 - 2750 - 4000 - 4000 - (4500 - 1000)$$$

Good Luck & Have Fun!

Update 1: The score distribution have been changed a bit. In particular, problem I will be split into two subtasks.

Update 2: Hacks will be disabled on problems A-D.

Update 3: editorial — https://codeforces.com/blog/entry/149944

Update 4: Congratulations to the winners!

1. maroonrk
2. ecnerwala
3. turmax
4. peti1234
5. kotatsugame
6. hos.lyric
7. BurnedChicken
8. strapple
9. stepanov.aa
10. antontrygubO_o

Hi Codeforces!

2025 comes to an end. However square the year was, we held a number of rounds: 29 Div. 1 and 31 Div. 2-only contests, to be precise! Additionally, 18 Div. 3, 4 Div. 4, and 13 Educational rounds made the schedule even more congested.

December is not only the perfect only time to wrap the year, but also to celebrate and thank all the people who made this year possible. That's why I want to highlight with this post the people whose efforts shaped Codeforces contests.

I'd like to say a huge thank you to every active community member who created and/or prepared problems for Codeforces rounds! Without your ideas and creativity, it would be impossible to hold so fun and interesting competitions. There are so many of you from every corner of the world, so that it's impossible to name everyone here, but one can see the authors of each contest on the contests page. Thank you!

Next, I'd like to extend my deepest gratitude to our coordinators who make sure rounds are the best quality and come on time. Here they are: Error_Yuan, maomao90, FairyWinx, Sugar_fan, satyam343, errorgorn, TheScrasse, 244mhq, Artyom123, Akulyat, Dominater069, flamestorm, abc864197532, cadmiumky, SSerxhs, Kaey, Vladithur, Um_nik, and Proof_by_QED coordinated Div. 1 and Div. 2 rounds this year. These people mostly worked after work of studies and sometimes even through the night to bring the rounds to you. An extra appreciation goes to Um_nik who now pre-reviews all round proposals, making sure the authors receive timely feedback. At the same time, BledDest and his team managed all the Educational rounds, Vladosiya managed all Div. 3 and Div. 4 rounds, with cry and soullless coordinating some of them. Thank you for your amazing work!

And last but not the least, I'd like to thank almost 800 testers who got to know the problems before the time, spotted some mistakes, and gave very useful advice to the problem authors. Again it's not possible to name them all, but huge shout-out to these heroes who tested the most rounds: _istil, chromate00, A_G, N_z__, larush, Error_Yuan, Proof_by_QED, Dominater069, __baozii__, Friedrich, -firefly-, madlogic, Um_nik!

Please join me in applauding all directly and indirectly mentioned people for their exceptional effort! Your work is invaluable for our community. Thank you! With that, I wish you all an exceptional New Year Eve and see you next year!

Hello Codeforces,

As 2025 comes to an end, it is time to start summing up the results.

This post is about the Global Rounds. Since September, we have held a series of three Global Rounds, numbered from 29 to 31.

This is the perfect moment to once again express our gratitude to XTX Markets for their initiative in organizing these rounds and their constant support over the years. Such stability in supporting the competitive programming movement is truly admirable and highly appreciated by the community. I wish XTX Markets a fantastic 2026, full of success and victories!

In each of the three rounds, 50 t-shirts were awarded (to the top 30 participants and 20 random participants ranked between 31st and 500th). This year, we had to change the manufacturing and shipping process, so it is still a work in progress, but things are moving forward, and shipping will begin soon. I would like to take this opportunity to ask the prize winners to respond promptly to any information requests and to meet the deadlines. It is also a good idea to keep your shipping address up to date at https://codeforces.com/settings/delivery.

The results for this series were calculated based on the best two performances out of the three possible rounds. Participants received points depending on their rank (points were awarded to the top 100 participants according to this table). The top 20 participants will receive commemorative hoodies and certificates indicating their rank.

Congratulations to the series winner ecnerwala on a decisive victory! Full results can be found at https://codeforces.com/contests/2147,2164,2180/gp100/best2/standings.

Thank you for participating in the rounds. Would you like another season of Global Rounds in 2026?

Mike

P.S. Here are the top 20 participants. Congratulations on winning a hoodie and a certificate!