Now that Goodbye 2022 has recently concluded (I hope you liked it). Let's share the best problems from 2022 instead of only before 3 weeks ago (I am looking at you kozliklekarsky).

Btw, I have noticed a trend in these blog posts where many problems come from the last few months of the year. So I hope that we take a good look through the contests of 2022 before posting.

Also, I think it would be a good idea to share your favourite blogs of 2022 as well in case we missed out some genius blog!

Thank you for rendering my blog useless. I thought we were friends.

Posting "Problem of the Year" 3 weeks before 2022 ends is stupid. Instead, you should have posted it in January 2022.

Bine antontrygubO_o. Se da un sir de cifre separate prin operatori '*', '+', '-', '/', '^', '&', 'XOR', '!' '|'. Avand voie sa faci maxim K interschimbari intre operatori, aflati valoarea maxima a expresiei. Marinush. Posting "Spotify Wrapped" 4 weeks (PATRU!!) before 2022 ends is stupid. Instead, you should've posted it in January 2012.

Elementar. Rezolvarea problemei necesita cunostinte despre evaluarea unei expresii aritmetice, programare dinamica.

Pentru rezolvarea problemei in cazul general vom nota cu a[1],a[2],...,a[m] operanzii expresiei si cu op[1],op[2],...,op[m − 1] operatorii expresiei, unde m = [N /2] + 1.De asemenea, notam cu d[i][j][h] valoarea maxima a expresiei, ce se obtine utilizand operanzii a[1],a[2],...,a[i], expresie in care s-au folosit j operatori diferiti fata de cei corespunzatori din expresia initiala, si h operatori de inmultire. Desigur, Valoarea lui d[i][j][h] se calculeaza dinamic (cu programari dinamice)

tibinyte always pushes his problemsI won't this time, my favorite problem this year was:

Caloriferwho am I kidding, of course it's Majority!problem

I loved this problem too

You know what? Let me just write a blog about calculating the diameter of a polygon using two pointers on the upper and lower hull, and point that blog as my favorite. THIS IS GONNA BE EPIC

UPD: Yes I did

Brother, errorgorn did nothing wrong, why are you so malicious.

Are you sure that's correct? I think rotating calipers is cleaner.

I know rotating calipers is one famous way to do it, but trust me, my algorithm is correct (tested with Robert Hood™), and I have proof that the diameter cannot be on the same side of the hull (excluding leftmost/rightmost points). I like the method because I am too stupid to understand Graham scan or Rotating calipers. (Yes, I would have used them if I understood them well enough) I am not really sure about how epic it is though

Not sure about problems, but I enjoyed reading this blog, even though a lot of it is well-known. It was nice seeing someone finally compile scattered information about hashing into one place.

SpoilerI was planning on writing a blog along similar lines (i.e., compiling some obscure but useful stuff), but in the end, I couldn't find a topic which doesn't have a good resource already.

If you want to see a blog on some idea, please reply with a suggestion about that idea. Perhaps I could try writing something if I get the time (and the motivation of course).

1621D - The Winter Hike, 1638D - Big Brush

1704D - Magical Array, 1704E - Count Seconds

1707B - Difference Array, 1710B - Rain, 1718C - Tonya and Burenka-179

1733C - Parity Shuffle Sorting, 1733E - Conveyor <- The author is me, but I thought it is great problem XD.

1746D - Paths on the Tree, 1746E1 - Joking (Easy Version)

1770D - Koxia and Game, 1770E - Koxia and Tree

The author is me, but I thought it is great problem XD.1758D - Range = √Sum This problem.

This problem was a great one.

Here are some problems I possibly liked/found interesting this year:

January: ARC133E — Cyclic Medians, CF768F — Making It Bipartite

March: CF774F — Playing Around the Table, ABC243Ex — Builder Takahashi (Enhanced version)

April: NERC 2021 K — Kingdom Partition

May: ARC141C — Bracket and Permutation, CF794F — The Ultimate LIS Problem

June: CF803F — Equal Reversal

July: CF CodeTON 2 E — Count Seconds, CF CodeTON 2 H1 — Game of AI (easy version)

September: ARC147D — Sets Scores, ABC269Ex — Antichain

October: ARC149D — Simultaneous Sugoroku

November: CF836F — Decent Division

Only problems from the contests I participated/upsolved soon/tested are included in the selection. I didn't participate a lot this year and I believe that lots of good problems aren't here just because of this (or because I accidentally forgot them).

Spotify, Reddit, Steam and maybe some other things post their yearly summaries in early December too. I don't get it. kozliklekarsky was just following their trend

1630F - Making It Bipartite

1633F - Perfect Matching

1634F - Fibonacci Additions

1637H - Minimize Inversions Number

1646F - Playing Around the Table

1656E - Equal Tree Sums

1672F2 - Checker for Array Shuffling

1685C - Bring Balance

1687E - Become Big For Me

1689E - ANDfinity

1707E - Replace

1718E - Impressionism

1738G - Anti-Increasing Addicts

1774G - Segment Covering

After having some time to understand the editorial for Good Bye 2022, I would add 1770H - Koxia, Mahiru and Winter Festival to the list. My favorite contest of the year was probably Codeforces Round 808 (Div. 1) but Good Bye 2022: 2023 is NEAR would be quite close to the top. Thanks to all the authors and coordinators!

Here's a list of my favourite tasks this year. Thanks to the authors!

I don't know if it's only me but I really enjoy reading blogs about cheaters a lot.

Because you want to know how to write a blog to say you're not a cheater when you've got skipped for the third time? (He's a cheater himself and he's been caught twice).

Well, I had cheated back then (and this is almost 9 months ago when I started CP) because I was very focused on my rating and was afraid of getting negative delta. Later on, I was overwhelmed with guilt and decided never to do it again.

If you were aware of that previous blog, you could have just commented there.

We will soon have "what is your favorite blog about your favorite problems in 2022"?

Problem, Nice problem, also Problem2

My favourite blog is Bakry's blog https://codeforces.com/blog/entry/110245 it is really inspiring.

My 2023 goals are to reach CM hopefully and to do well in my country's National Olympiad.

Happy New Year Every One, Hope you all achieve your Goals.

Bakry

some of my favorite tasks in 2022:

From Atcoder:

From Codeforces:

Others:

obviously goodbye 2022 C

Did not do problems on other OJs as much so this list only mainly contains problems from CF

commentsThis problem is a horrible div 2B but its the greatest anti-problem this year. Definitely one of the most memorable div 2Bs of all time.

commentsOriginal constraints are not that interesting. The thing I like about this problem is that we can prove that the answer obeys a linear recurrence of length $$$K$$$ which can be calculated in $$$O(2^K)$$$ time.

commentsIdea is really nice but the implementation is not fun.

commentsAuthors proposed this as d1A

Also some problems from atcoder that I recall (wasn't really active on atcoder though)

Others:

commentsThis is definitely bias from this being such a recent contest but I can't believe the 3-5th place (including me) choked on such a simple (in hindsight) greedy observation

commentsflamestorm proposed this for a contest but a tester found out it had appeared earlier in 2022 so we could not use it. Very sad, was my favourite problem of the contest.

Unfortunately, I don't have any favorite problems in 2022. APIO2022B, AGC059C, IOI2022F deserve some honorable mentions, I think.

I think these Codeforces problems were good:

1634F - Fibonacci Additions

1637G - Birthday

1682E - Unordered Swaps

1698F - Equal Reversal

1707F - Bugaboo

1737D - Ela and the Wiring Wizard

1774G - Segment Covering

1770F - Koxia and Sequence

Honorable mention: 1685E - The Ultimate LIS Problem