### cry's blog

By cry, 4 days ago,

In the comments section of my most recent round, there has been a lot of misconceptions about interpreting score distribution. This blog is just to inform the correct way of understanding them from a problemsetter standpoint.

The biggest misconception I saw was score distributions are always almost equal to its difficulty. This is not true. Do you really think 1852A - Ntarsis' Set is a rated 500 problem?

The correct way to interpreting score distribution is looking at the differences between each adjacent gaps. I will give suggestions on interpreting difference in points in a Div. 2 round. Div. 1 Scoring may be different because the difficulty curve is different.

Usually, a $250$ point gap means the two problems are relatively similar in difficulty but with a slight difficulty increment. A $500$ point gap represents the standard gap between adjacent problems that you'd expect. I think any gap $750$ or above means there is a decently large difficulty discrepancy between the two problems. I will use Codeforces Round 965 (Div. 2) as an example.

Problems A and B are expected to be similar difficulty with B being slightly challenging. B and C are $500$ apart, which means that the difficulty difference between B and C is expected to be larger than that for A and B. In hindsight, I probably should've assigned a $750$ point difference. This is also why you shouldn't rely on score distribution to determine whether you should approach a problem or not, as the assigned difference could be higher or lower than the actual gap. Again, there is a $250$ gap between C and D so they are expected to be relatively close in difficulty but D should still be harder than C; same for D and E1.

Problems with subtasks usually come with $(x + y)$ in the announcement blog, with $x$ being the score assigned to the easy version and $y$ for the harder version. In most round, this usually means that if the easy version is a stand-alone problem, then it should be assigned $x$ points. If only hard version is proposed, then it should be worth $x+y$ points. However, I don't believe that this should always be the case in the future, which is why this blog is also a suggestion to future problemsetters.

Originally, E1 was going to be assigned $2000$ points and E2 assigned $1000$ points. Then, one of our testers, Dominater069 said "I wrote 10 mins of ds for E1 for $2000$ points... And then take 30 mins just for $1000$ points?" I thought about this and I was like, he has a point. There has been a lot of instances where the hard version is a lot harder than the easy version, but isn't worth a significant amount of points on its own. Therefore, I think setters should weigh the hard version like a standalone problem, and decrease its value based on how much of the observation that the easy version gives away.

Lastly, score distributions aren't always accurate. They are usually only decided by setters, the coordinator, and a small subset of the testers. You shouldn't get scared if you see a large score gap between problems. Most of the time, us setters also get surprised by the performance of you codeforcers.

• +176

By cry, 2 weeks ago,

## Wazzup Codeforcers!

sum, satyam343, and I are extremely ecstatic to invite you to Codeforces Round 965 (Div. 2) on Aug/10/2024 17:35 (Moscow time). You will be given 5 problems and 2 hours to solve them. 1 problem will have subtasks. This round will be rated for all participants with rating below 2100. We spent the most time cooking up this round than any other round, so it means a lot if you will participate.

We would like to orz the following individuals for making the contest possible:

Score Distribution: $500 - 750 - 1250 - 1500 - (1750 + 1750)$

#### UPD: Editorial

• +265

By cry, 3 weeks ago,

I accidentally copied a CodeChef problem.

I was just made aware by satyam343 that 1996A - Legs somehow COINCIDES EXACTLY with FARMLEGS.

I had zero idea this problem even existed before right now. I even thought satyam343 was trolling and thought this problem was only published after my contest. It wasn't until I looked at submission dates that I noticed the problem was created more than three months ago... My problem was based on a mixture of middle-school word problems and me casually thinking of USACO cows.

Regarding how even the constraints are exactly the same: The constraints were initially $t \leq 10^5$ and $n \leq 2 \cdot 10^5$, but a tester did $O(tn)$ and still passed all test cases. Obviously, this is hackable, so we have to either decide to add a third test case with all tests being $2 \cdot 10^5$ or make $O(tn)$ comfortably pass. We didn't want to blow up queue even more, so we resorted to the latter option.

Anyways, this is way too funny, so I have to make a blog. This is also even more ironic since I advertised a CodeChef contest in the comments :skull:

• +187

By cry, 6 weeks ago,

## Hewwo Cowodeforcers!

sum and I are overjoyed to welcome you to participate in Codeforces Round 962 (Div. 3) on Jul/26/2024 17:35 (Moscow time). This contest is the last stop on our mission to problemset for every division. We hope you've been enjoying our stuff so far!

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

You will be given 7 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for each wrong submission in this round is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

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

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.

We would like to orz the following individuals for making the contest possible:

Thank you for reading and we hope you have a fun and educational interstellar adventure :3

### UPD: Editorial

• +423

By cry, 5 weeks ago,

1996A - Legs

Problem Credits: cry
Analysis: cry

Solution
Code (C++)

1996B - Scale

Problem Credits: sum
Analysis: cry

Solution
Code (C++)

1996C - Sort

Problem Credits: cry
Analysis: cry

Solution
Code (C++)

1996D - Fun

Problem Credits: sum
Analysis: cry

Solution
Code (C++)

1996E - Decode

Problem Credits: cry
Analysis: cry

Solution
Code 1 (C++)
Code 2 (A Little Different) (C++)

1996F - Bomb

Problem Credits: sum
Analysis: cry

Solution
Code 1 (C++)
Code 2 (C++)

1996G - Penacony

Problem Credits: cry
Analysis: cry, awesomeguy856

Solution - Segment Tree
Code (C++)
Solution - XOR Hashing (by awesomeguy856)
Code (C++)
• +110

By cry, 2 months ago,

#### 1998A - Find K Distinct Points with Fixed Center

Problem Credits: sum
Analysis: cry

Solution
Code (C++)

#### 1998B - Minimize Equal Sum Subarrays

Problem Credits: satyam343
Analysis: cry

Solution
Code (C++)

#### 1998C - Perform Operations to Maximize Score

Problem Credits: cry, satyam343
Analysis: sum, satyam343, Dominater069

Hint 1
Hint 2
Hint 3
Solution
Code (C++)

#### 1998D - Determine Winning Islands in Race

Problem Credits: cry
Analysis: cry

Solution
Code (C++)

#### 1998E1 - Eliminating Balls With Merging (Easy Version)

Problem Credits: cry, sum, satyam343
Analysis: sum

Solution 1
Code 1 (C++)
Solution 2
Code 2 (C++)

#### 1998E2 - Eliminating Balls With Merging (Hard Version)

Problem Credits: cry, sum, satyam343
Analysis: sum

Solution
Code (C++)
• +151

By cry, 5 months ago,

## Hellowo Codeforcers :3

sum and I are very delighted, ecstatic, enchanted, euphoric, excited, exultant, jubilant, overjoyed, and proud to invite you to participate in Codeforces Round 952 (Div. 4), which will start on Jun/11/2024 17:35 (Moscow time). There will be $8$ problems, with one split into two subtasks, to be solved in $2.5$ hours.

As usual, I have to copy and paste the following...

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 recalculated
• by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).

We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.

Only trusted participants of the fourth division will be included in the official standings table. This is a forced measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:

• take part in at least five rated rounds (and solve at least one problem in each of them),
• do not have a point of 1400 or higher in the rating.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), then the round will be rated for you.

We want to express overwhelming gratitude to the following individuals for making the contest possible:

Vladosiya and mesanu for coordinating the contest and reviewing the problems.

Dominater069, omeganot, Phi-001, flamestorm, nskybytskyi, willy108, ScarletS, mark, yuan-shen, vgoofficial, htetgm, buffering, yash_9a3b, haochenkang, ETL, natalina, MatthewC3297, and lcsc0 for testing the round.

MikeMirzayanov for the usual.

We suggest reading all of the problems as we have put mucho effort into all of them. Best of luck, mis amigos!

UPD: Editorial

• +363

By cry, 3 months ago,

This was our first time setting a Div.4 contest. We sincerely hope you enjoyed the problems!

##### 1985A - Creating Words

Problem Credits: cry
Analysis: cry

Solution
Code (C++)
##### 1985B - Maximum Multiple Sum

Problem Credits: cry
Analysis: cry

Solution
Code (C++)
##### 1985C - Good Prefixes

Problem Credits: sum
Analysis: cry

Solution
Code (C++)
##### 1985D - Manhattan Circle

Problem Credits: cry
Analysis: cry

Solution
Code (C++)
##### 1985E - Secret Box

Problem Credits: cry
Analysis: cry

Solution
Code (C++)
##### 1985F - Final Boss

Problem Credits: cry, sum
Analysis: cry, sum

Solution
Code (C++)
Bonus
##### 1985G - D-Function

Problem Credits: cry
Analysis: cry

Solution
Code (Python)
##### 1985H1 - Maximize the Largest Component (Easy Version)

Problem Credits: sum
Analysis: sum

Solution
Code (C++)
##### 1985H2 - Maximize the Largest Component (Hard Version)

Problem Credits: sum
Analysis: sum

Solution
Code (C++)
• +113

By cry, 6 months ago,

# Hello Codeforcers!

We are pleased to invite you to participate in CodeTON Round 8 (Div. 1 + Div. 2, Rated, Prizes!). This round will start on Mar/30/2024 17:35 (Moscow time) and will be rated for all participants. There will be $8$ problems to be solved in $3$ hours, with one divided into two subtasks. Similar to USACO, you will help Farmer John and his cows resolve a series of first world problems. Be there or be square.

This round was cooked up by smax, sum, oursaco, cry, and buffering.

We would like to thank the following people for making the round possible:

#### Score Distribution:

$500 - 1000 - (1250 + 750) - 2250 - 2500 - 3000 - 3000 - 4500$

#### Editorial

Congratulations to our Winners and First Solves!

Top 5:

First Solves:

A. A_G
B. jiangly
C1. ksun48
C2. turmax
D. Omer223
E. tourist
G. tourist
H. ecnerwala

And here is the information from our title sponsor:

Hello, Codeforces!

We, the TON Foundation team, are pleased to support CodeTON Round 8.

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

Since July 2022, 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 8 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 8 and hope you enjoy the contest!

• +505

By cry, 5 months ago,

Thank you for participating! We put a lot of effort into this contest. Special thanks to TheScrasse for contributing to these problems.

Rating Predictions

#### Solutions

##### 1942A - Farmer John's Challenge

Problem Credits: buffering
Analysis: buffering

Hint 1
Hint 2
Hint 3
Solution
Code (C++)
##### 1942B - Bessie and MEX

Problem Credits: buffering
Analysis: buffering

Solution 1

Hint 1
Hint 2
Solution
Code (C++)

Solution 2

Hint 1
Hint 2
Solution
##### 1942C1 - Bessie's Birthday Cake (Easy Version) and 1942C2 - Bessie's Birthday Cake (Hard Version)

Problem Credits: cry
Analysis: cry

Solution (Easy Version)
Solution (Hard Version)
Code (C++)

#### 1942D - Learning to Paint

Problem Credits: sum
Analysis: sum

Hint 1
Hint 2
Solution
Code (C++)

#### 1942E - Farm Game

Problem Credits: cry
Analysis: sum

Hint 1
Hint 2
Hint 3
Solution
Code (C++)

#### 1942F - Farmer John's Favorite Function

Problem Credits: sum
Analysis: sum

Hint 1
Hint 2
Hint 3
Hint 4
Solution
Code (C++)

#### 1942G - Bessie and Cards

Problem Credits: smax
Analysis: smax

Hint 1
Hint 2
Solution
Code (C++)

#### 1942H - Farmer John's Favorite Intern

Problem Credits: oursaco
Analysis: oursaco / rainboy

Solution 1
Code (C++)
Solution 2
Code (C++)
• +143

By cry, 11 months ago,

Recently, around daily at around this time (9PM EST), when I try to edit a problem in Polygon I just get greeted with blank screen. The main view problems page seems fine though.

Is polygon just down everyday at this time or is it just me? Do I have too many created problems in my account lol? When I view console it just displays this:

• +6

By cry, 13 months ago,

# Hello Codeforcers :3

UPD 2: Contest has started! You may start your window anytime over the next 2 days. Join our Discord server to ask clarifications for any problems. Good luck!

From the authors behind Codeforces Round 887 (Div. 1) and Codeforces Round 887 (Div. 2), CerealCodes is excited to announce our Summer 2023 Programming Contest!

This contest will be held on August $13 - 15$ th with a customizable time-frame window. The time limit for novice is $3$ hours while intermediate and advanced are allowed $3.5$ hours. All of the contest information, including exact start and end times, can be found here.

The competition has three divisions: Novice (USACO Bronze-Silver or Div. 3), Intermediate (USACO Silver-Gold or Div. 2), and Advanced (USACO Gold-Platinum or Div. 1).

You can form teams of up to $3$ members, and compete to solve $\approx 10$ high quality problems within your time frame.

Over \$1500 in cash (possibly more) will be given out (in the form of Amazon gift cards), as well as other prizes like merchandise and raffle awards! Note: only pre-college teams are eligible for cash awards, but everyone is still eligible to participate.

All of the logistics, registration, and the contest platform will be held on our website.

The problems were invented and written by our problemsetting team: wavelets, Apple_Method, oursaco, omeganot, sum, null_awe, izhang, cry, thehunterjames, Ina, Whimpers, timg8710, buffering, ntarsis30, Cereal2, Alg01, asdf1234coding, dutin, and ArielShehter.

Big thanks to our problem testers as well: EmeraldBlock and GusterGoose27; and our web + contest platform developers: xiaossr, mirachael, SwayamSahoo11742, cryan., br1ck, and _monitor.

Last year's contest can be found here.

## Register Here

We hope to see you there!

CerealCodes Team

• +126

By cry, 14 months ago,

## Hello Codeforcers!

I am pleased to invite y'all to participate in Codeforces Round 887 (Div. 1) and Codeforces Round 887 (Div. 2), which will start on Jul/23/2023 17:35 (Moscow time). In both divisions, you will be given $6$ problems and $2.5$ hours to solve them. The Div. $2$ round will be rated for participants with rating below $1900$, while the Div. $1$ round will be rated for participants with ratings which are at least $1900$.

This round was authored and prepared by Benq, emorgan, omeganot, US3RN4M3, me (cry), Ina, nsqrtlog, buffering, ntarsis30, and ArielShehter.

We want to thank the following people for their contributions:

UPD 1: Score Distribution

Div. $2$: $500 - 1000 - 1500 - 2000 - 2500 - 3500$

Div. $1$: $500 - 750 - 1250 - 2000 - 2250 - 3000$

UPD 2: Editorial has been posted here

UPD 3: Congratulations to the winners!

Div.1

Div. 2

Good luck! Red panda wishes you all rating inflation!

Art credit to xiaossr

• +575

By cry, 14 months ago,

We hope you enjoyed these problems :) This contest has been in the works for almost a year.

UPD: D1D Editorial have been updated

UPD 2: D1D Editorial now has images by EmeraldBlock. As an apology gift for being so slow, the image generator is programmatic and available here.

#### 1853A - Desorting

Problem Credits: buffering

Analysis: buffering

Hint 1
Solution
Code (C++)

#### 1853B - Fibonaccharsis

Problem Credits: ntarsis30, cry

Analysis: cry

Hint 1
Solution
Code (C++)

Bonus: Solve for $n, k \leq 10^9$

Bonus Solution

#### 1852A - Ntarsis' Set

Problem Credits: nsqrtlog

Analysis: nsqrtlog, buffering

Hint 1
Hint 2
Solution
Code (C++) -- Model Solution
Code (C++) -- Simulation (more readable)

#### 1852B - Imbalanced Arrays

Problem Credits: nsqrtlog

Analysis: buffering, nsqrtlog

Hint 1
Hint 2
Hint 3
Hint 4
Solution
Code (C++)

#### 1852C - Ina of the Mountain

Problem Credits: Ina

Analysis: Ina, EmeraldBlock, GusterGoose27

Hint One
Hint 2
Hint 3
Tutorial
Code (C++)

#### 1852D - Miriany and Matchstick

Problem Credits: ArielShehter

Analysis: EmeraldBlock, emorgan

Hint 1
Hint 2
Hint 3
Hint 4
Solution
Code (C++)

#### 1852E - Rivalries

Problem Credits: buffering, ArielShehter, Ina

Analysis: oursaco

Hint 1
Hint 2
Hint 3
Hint 4
Solution
Code (C++)

#### 1852F - Panda Meetups

Problem Credits: Benq

Analysis: Benq, oursaco

Hint 1
Hint 2
Hint 3
Hint 4
Solution
Code (C++)
• +183

By cry, history, 3 years ago,

You can now name your variables with emojis in C++20 :D

Proof of C++20 submission: https://mirror.codeforces.com/contest/80/submission/140848199

It does not work in other C++ versions, such as C++17: https://mirror.codeforces.com/contest/80/submission/140847859

This is a revolutionary moment in variable naming, and an incredible breakthrough for the community <3

• +153