Akikaze's blog

By Akikaze, 14 months ago, In English

We apologize for the huge gap from F to G.
In the meantime, you can join the Discord server of AC — a competitive programming forum — here.

1305A - Kuroni and the Gifts

Author: Ari
Development: Ari, dorijanlendvaj
Editorialist: Ari

Tutorial
Solution (Ari, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1305B - Kuroni and Simple Strings

Author: xuanquang1999 (remixed by antontrygubO_o)
Development: Ari, Kuroni, xuanquang1999
Editorialist: antontrygubO_o

Tutorial
Solution (Ari, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1305C - Kuroni and Impossible Calculation

Author: antontrygubO_o
Development: antontrygubO_o, dorijanlendvaj, Kuroni, Ari
Editorialist: antontrygubO_o

Tutorial
Solution (antontrygubO_o, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1305D - Kuroni and the Celebration

Author: Akikaze
Development: Akikaze, dorijanlendvaj
Editorialist: Kuroni

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1305E - Kuroni and the Score Distribution

Author: antontrygubO_o
Development: xuanquang1999
Editorialist: antontrygubO_o

Tutorial
Solution (xuanquang1999, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1305F - Kuroni and the Punishment

Author: Kuroni
Development: Ari, 265918, Kuroni, dorijanlendvaj, xuanquang1999
Editorialist: Ari

Tutorial
Solution (Kuroni, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, PyPy 3)

1305G - Kuroni and Antihype

Author: antontrygubO_o
Development: antontrygubO_o, Kuroni
Editorialist: antontrygubO_o

Tutorial
Solution (Approach #1) (kefaa2, C++)
Solution (Approach #2) (Kuroni, C++)

1305H - Kuroni the Private Tutor

Author: zscoder
Development: zscoder, ngfam, Kuroni, antontrygubO_o
Editorialist: zscoder

Tutorial
Solution (zscoder, C++)

Read more »

 
 
 
 
  • Vote: I like it
  • +155
  • Vote: I do not like it

By Akikaze, 16 months ago, In English

"Can you hear me?"

"Vanessa...?"

Hello Codeforces!

We are here to invite you to Codeforces Round #614 (Div. 1) and Codeforces Round #614 (Div. 2), which will take place at Jan/19/2020 16:35 (Moscow time). The round is rated for both divisions.

This is our first round including Div.1 parts, hopefully you'll find the problems interesting. ;)

This round is themed based on the Rayark Inc.'s rhythm game, "Cytus II". You are about to help our characters in various problems, whether inside or outside of the virtual Internet! Also, feel free to listen to the music tracks I've chosen from the game for each problem (and later, editorial!). ;)

Each division will be given 6 problems to solve in 2 hours. The round's problems were prepared by Xuan-Quang xuanquang1999 D. Nguyen, Duy-Bach Akikaze Le and Tuan-Dung low_ To.

Interactive problem(s) might be found in this round. Learn about them here.

We also want to thanks our friends for helping this contest being possible:

  • Our dear Codeforces coordinator Dmitry cdkrot Sayutin for reviewing our problems, and roasting a whole bunch of them as well. :D
  • Grigory vintage_Vlad_Makeev Reznikov, Quang-Minh MofK D. Nguyen, Yufan ouuan You and Sooke for helping us in preparing and adjusting difficulties of a few problems.
  • Anton antontrygubO_o Trygub, Duc-Trung Kuroni D. Dang and Duy-Thuc leduythuc Le for being our testers.

Last but not least, I want to give a huge appreciation to MikeMirzayanov for the awesome Codeforces and Polygon platform, which makes this contest possible.

Wish everyone good luck and high rating!

UPD1: Editorial is available here.

UPD2: Many more testers helped us in this round! Huge thanks to Kevin ksun48 Sun, Andrew ecnerwala He, Aydar aid Sayranov, Nikolay KAN Kalinin, Oleg Mustang98 Vallas, Mohammed mohammedehab2002 Ehab, Artem Rox Plotkin, Mingming Nero Zhang, Darko Aleksic, Ilya IlyaCk Porublyov, NatInTheHat and NIWIS!

UPD3: Score distribution:

  • Div. 1: 500-750-1250-1750-2250-2750
  • Div. 2: 500-750-1250-1500-2000-2500

UPD4: True editorial is available here!

UPD5: The contest is over. Thanks for participating, and here are the winners:

  • Div. 1:
  1. Um_nik (first to solve F)
  2. tourist (first to solve A, B, D and E)
  3. Benq
  4. HIR180
  5. jiangly
  6. TLE
  7. AprilGrimoire
  8. Golovanov399
  9. cz_xuyixuan
  10. fateice
  • Div. 2:
  1. DestinyFucker9000 (solved all Div.2 problems!)
  2. about
  3. Isaunoya
  4. espr1t
  5. kkktl01
  6. the_happy_camel
  7. changruinian2020
  8. Agarifighter
  9. Small_Pax
  10. TaeHo0o00o0N

Also, as the direct setter of Div1B/Div2D, I sincerely apologized for the weak testsets. I must admit, I underperformed this time, and might cause some of you inconvenience. Hope to see you guys another time with a better contest.

Read more »

 
 
 
 
  • Vote: I like it
  • +703
  • Vote: I do not like it

By Akikaze, 16 months ago, In English

All themes written by Akikaze (I am the only one in the team playing Cytus II anyway :D).

1293A - ConneR and the A.R.C. Markland-N

Author: xuanquang1999
Development: xuanquang1999, Akikaze
Editorialist: xuanquang1999, Akikaze

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1293B - JOE is on TV!

Author: Akikaze
Development: Akikaze
Editorialist: Akikaze

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1292A - NEKO's Maze Game

Author: xuanquang1999
Development: xuanquang1999, Akikaze
Editorialist: Akikaze

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1292B - Aroma's Search

Author: Akikaze feat. xuanquang1999
Development: xuanquang1999, Akikaze
Editorialist: Akikaze

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1292C - Xenon's Attack on the Gangs

Author: xuanquang1999
Development: xuanquang1999
Editorialist: xuanquang1999

Tutorial
Solution (xuanquang1999, C++)
Solution (xuanquang1999, Java 8)

1292D - Chaotic V.

Author: Akikaze
Development: Akikaze
Editorialist: Akikaze

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, PyPy 3)

1292E - Rin and The Unknown Flower

Author: low_ (Sooke Remix)
Development: low_, Sooke, Akikaze
Editorialist: low_

Tutorial
Solution (Akikaze, C++)
Solution (Akikaze, Java 8)
Solution (Akikaze, Python 3)

1292F - Nora's Toy Boxes

Author: xuanquang1999 × MofK
Development: xuanquang1999
Editorialist: xuanquang1999

Tutorial
Solution (xuanquang1999, C++)
Solution (xuanquang1999, Java 8)
Solution (xuanquang1999, PyPy 3)

Read more »

 
 
 
 
  • Vote: I like it
  • +202
  • Vote: I do not like it

By Akikaze, history, 2 years ago, In English

1152A - Neko Finds Grapes

Author: xuanquang1999
Development: xuanquang1999, Akikaze, GreenGrape
Theme development: Akikaze, GreenGrape
Editorialist: xuanquang1999

Tutorial
Solution (xuanquang1999)

1152B - Neko Performs Cat Furrier Transform

Author: Akikaze
Development: Akikaze, xuanquang1999
Theme development: Akikaze
Editorialist: Akikaze

Tutorial
Solution 1 - Greedy (Akikaze)
Solution 2 - BFS (Akikaze)

1152C - Neko does Maths

Author: stefdasca
Development: stefdasca, Akikaze
Theme development: xuanquang1999, neko_nyaaaaaaaaaaaaaaaaa
Editorialist: stefdasca

Tutorial
Solution (implemented by stefdasca)
Solution (implemented by Akikaze)

1152D - Neko and Aki's Prank

Author: cdkrot
Development: cdkrot
Theme development: xuanquang1999
Editorialist: cdkrot

Tutorial
Solution (_kun_)

1152E - Neko and Flashback

Author: xuanquang1999
Development: xuanquang1999
Theme development: xuanquang1999
Editorialist: xuanquang1999

Tutorial
Solution (xuanquang1999)

1152F1 - Neko Rules the Catniverse (Small Version)

1152F2 - Neko Rules the Catniverse (Large Version)

Author: MofK
Development: MofK, xuanquang1999, Akikaze
Theme development: xuanquang1999, Akikaze
Editorialist: MofK, Akikaze

Tutorial - F1 (Small version)
Tutorial - F2 (Large version)
Solution F1 (xuanquang1999)
Solution F2 (xuanquang1999)
Solution F2 (veryheckingfast by MofK)
Bonus

Authors' logs (miscellaneous things during our preparations)

Read more »

 
 
 
 
  • Vote: I like it
  • +115
  • Vote: I do not like it

By Akikaze, history, 2 years ago, In English

Once again, TREMBLE BEFORE THE MIGHTY OMEGALULRIPGRAPE.

(He last walked the Earth in round 538 btw.)

Hello Codeforces!

We are here to invite you to Codeforces Round #554 (Div. 2), which will take place at Apr/24/2019 17:35 (Moscow time).

The round will be rated for all Division 2 participants (with rating less than 2100), yet any Division 1 participants are welcome to join us out of competition.

The round will be cat themed. Raise your paws and prepare your catnips!

(Or even cat memes, while you're at it).

You will be given 6+1 problems ( 6 problems, one of them has 2 subtasks ) to solve in 2 hours. The round's problems were prepared by Xuan-Quang xuanquang1999 D. Nguyen, Duy-Bach Akikaze Le, Stefan stefdasca Dascalescu, Quang-Minh MofK D. Nguyen and our dear Codeforces coordinator Dmitry cdkrot Sayutin.

Gladly (or sadly), no interactive problem tonight!

Also, the tribute should be given to everyone within the team — we all make it possible:

  • Andrew GreenGrape Rayskiy for various problem suggestions and the infamous OMEGALULRIP influence. ;)
  • Xuan-Tung neko_nyaaaaaaaaaaaaaaaaa Nguyen for testing the rounds and various suggestions in the core theme idea. Nya~.

Last but not least, I want to give a huge appreciation to MikeMirzayanov for the awesome Codeforces and Polygon platform, which makes this contest possible.

P/s: I will be at the Discord CP Community to discuss the problems after the coding phase. However, please follow the rules and don't discuss the problems during the contest by any means.

Wish everyone good luck and high rating!

P/s(2): Commies united!

P/s(3): A dear thank-you to Grigory vintage_Vlad_Makeev Reznikov for the last-minute complete testing as well! ;)

UPD1a: Another comrade, Quang-Minh MofK D. Nguyen joined the fun! Kudos for the problem suggestion! ;)

UPD1b: The problemset contains 6+1 problems ( 6 problems, one of them has 2 subtasks ).

UPD2: Score distribution: 500-1000-1500-2000-2000-(2250+750).

UPD3: Editorial will be available tomorrow. Sorry for the waiting, we have quite a lot of things to polish. ;)

UPD4: The contest is finished. I hope that you're satisfied. And here come our winners ;)

Official participants:

  1. hamzzq
  2. davidHernandes
  3. oiyoayao
  4. ItstInternationalTourist
  5. OnionGod
  6. IPL
  7. memset_inf
  8. dsgsjk
  9. FluffyT (the only official participants solved F1+F2, too bad she didn't solve E :<)
  10. _wxw_

Div.1 + Div.2 participants:

  1. dreamoon_love_AA (solved all problems!)
  2. pwild
  3. Heltion
  4. hamzzq
  5. natsugiri
  6. kmjp
  7. davidHernandes
  8. Jeffrey
  9. betrue12
  10. KrK

UPD5: Editorial blog post is available.

Read more »

 
 
 
 
  • Vote: I like it
  • +436
  • Vote: I do not like it

By Akikaze, 2 years ago, In English

Model solutions are now available.
GreenGrape and I will write more about problem F, including an alternative data structures (still quite tight on time limit) ;)

1114A - Got Any Grapes?

Author: Akikaze, GreenGrape
Development: Akikaze, GreenGrape, neko_nyaaaaaaaaaaaaaaaaa
Editorialist: Akikaze

Tutorial
Solution (Akikaze)

1114B - Yet Another Array Partitioning Task

Author: xuanquang1999
Development: Akikaze, xuanquang1999
Editorialist: xuanquang1999, neko_nyaaaaaaaaaaaaaaaaa

Tutorial
Solution (xuanquang1999)

1114C - Trailing Loves (or L'oeufs?)

Author: Akikaze
Development: Akikaze, majk, cdkrot
Editorialist: Akikaze

Tutorial
Solution (Akikaze)

1114D - Flood Fill

Author: neko_nyaaaaaaaaaaaaaaaaa
Development: Akikaze, neko_nyaaaaaaaaaaaaaaaaa, cdkrot
Editorialist: neko_nyaaaaaaaaaaaaaaaaa, cdkrot

Tutorial
Solution 1 (_kun_)
Solution 2 (neko_nyaa)

1114E - Arithmetic Progression

Author: Akikaze
Development: Akikaze, GreenGrape
Editorialist: Akikaze, xuanquang1999

Tutorial
Solution (Akikaze)

1114F - Please, another Queries on Array?

Author: Akikaze, cdkrot
Development: Akikaze, GreenGrape, cdkrot
Editorialist: Akikaze, GreenGrape, cdkrot

Tutorial
Solution 1a (_kun_)
Solution 1b (Akikaze) [literally kun's solution, yet shorter, and a bit uglier :P]
Solution 2 (GreenGrape)

Read more »

 
 
 
 
  • Vote: I like it
  • +148
  • Vote: I do not like it

By Akikaze, history, 2 years ago, In English

TREMBLE BEFORE THE MIGHTY OMEGALULGRAPE

Hello Codeforces!

We are honored to invite you to Codeforces Round #538 (Div. 2), which will take place at Feb/10/2019 17:05 (Moscow time). The round will be rated for all Division 2 participants (with rating less than 2100). Still, we warmly welcome Division 1 participants to join us out of competition.

You will be given 6 problems to solve in 2 hours. The round's problems were initially prepared by Duy-Bach Akikaze Le, Xuan-Tung neko_nyaaaaaaaaaaaaaaaaa Nguyen and Xuan-Quang xuanquang1999 D. Nguyen.

There will be an interactive problem in this round. Learn more about interactive problems here.

This is our first attempt in making a Codeforces round, so suggestions are much welcome to help us improve ourselves. ;)

We also want to thanks many friends for making this round possible:

  • Dmitry cdkrot Sayutin for coordinating the round, providing a neat idea on one problem and some Russian translations.
  • Andrew GreenGrape Rayskiy for various suggestions on the problems, some other Russian translations, and most importantly, peacefully submitted himself to be quarantined from pretests. ;)
  • Michal majk Svagerka for testing the round.
  • And last but not least, Mike MikeMirzayanov Mirzayanov for the amazing Codeforces and Polygon platform, without which this round would never be possible :D

P/s: I will be at the Discord CP Community to discuss the problems after the coding phase. However, please follow the rules and don't discuss the problems during the contest by any means.

Wish everyone good luck and high rating!

UPD1: Score distribution: 500-1250-1500-2000-2000-2750

UPD2: Editorial is published.

UPD3: The contest is finished. I apologized for the "somewhat" weak pretests at here and there. Anyway, time to celebrate our winners ;)

Official participants:

  1. xlk200
  2. vasilescu_mihai
  3. Cirno_9baka
  4. africamonkey
  5. 2019_BecameMaster
  6. cdsfcesf
  7. yww_AFO
  8. hr_tian_xia_di_2
  9. JZmster
  10. chinmay0906

Div.1 + Div.2 participants:

  1. Hazyknight
  2. tfg
  3. tempura0224
  4. xlk200
  5. sava-cska
  6. mango_lassi
  7. I_love_Tanya_Romanova
  8. ec24
  9. vasilescu_mihai
  10. Cirno_9baka

Read more »

 
 
 
 
  • Vote: I like it
  • +573
  • Vote: I do not like it

By Akikaze, history, 2 years ago, In English

Since the original data has been lost during the dark days of Codeforces, no version of the editorial has been re-released, and I feel the round itself is quite educational, so I decided to give a try.

390A - Inna and Alarm Clock

Approach
Solution 1 (Map)
Solution 2 (Array)

390B - Inna, Dima and Song

Approach
Solution

390C - Inna and Candy Boxes

Approach
Solution

390D - Inna and Sweet Matrix

Approach
Solution

390E - Inna and Large Sweet Matrix

Approach
Solution

Read more »

 
 
 
 
  • Vote: I like it
  • +37
  • Vote: I do not like it

By Akikaze, history, 3 years ago, In English

First note: All observations are from my computer screen with the resolution of 1366 × 768. OS is Windows 10, browsing Codeforces using Google Chrome and coding using Code::Blocks 17.12. People with high-end computers/monitors or different software usages might experience differently or less inconvenient, yet the problem itself is still there.

TL;DR: The source codes presented through the "block code" format in Codeforces blog post should be made slightly smaller in terms of font size, and with less line spacing. A suggestion might be making it similar to the source code presented in the submission pages.

Many problem setters prefer showcasing model solutions on spoilers and direct sourcecode-formatting on blog posts (most notable ones are PikMike and Vovuh). I myself particularly enjoy this design, since the source code is collapsible and you won't lose the editorial tab you're watching (clicking any external links normally will not open it in a new tab, so sometimes it'd be annoying). However, the way the source codes are formatted seems to discourage some people (including me) from reading it.

I know reading source codes should be the last resort, if the editorial texts failed to explain things to you or the implementation intended in some parts was too complex that words couldn't make it. However, there has to be some times for some people to rely on this feature, and if that time comes, it should be made right.

Let's take the editorial blog post of Codeforces Round #515 for example.

Our target is problem D's solution by Vovuh.

Let's assume that I'm a newcomer intending to read the model solution. And this should be how the webpage is positioned when I open the source code (even this one is quite optimal):

Doesn't seem right. I can't even read the main function yet (the I/O optimization doesn't make up anything of the solution, and the find() function above is obviously not the total solution).

And by my estimation, the full solution takes up 1.5 screens. For anyone that have solved 1066D - Boxes Packing, the model solution can't be that tremendously long right?

So I copy-pasted the solution and submitted it to some random problem (I don't want to get another AC, just to test the source code representation). And this is what I have (submission link here):

It fits in just right. Difference in the very same platform.

Let's take another example. The target is the editorial blog post of Educational Codeforces Round 53 — to be specific, problem G and its model solution by adedalic.

And I have this:

Oh great. Now I can't even read anything further than macros and constant declarations.

To be honest, this one is a long solution indeed (compared to model solutions for casual problems). Let's diagnose deeper.

I copied the source code into my IDE. The source code is 175 lines long, and a screen in my IDE can show 39 lines:

Previewing it in Codeforces' submission page results in this (the link is here):

54 lines of source code visible. Technically it's similar to my IDE, just the full screen makes the result better a bit.

And in the blog post:

36 lines. 33.33% fewer than the submission pages. The rate is incredibly high.

Then what causes such differences?

Looking into the two screenshots again, we can see two points:

  1. The font size in the blog post is slightly bigger than in the submission pages. This one might be neglected in some extents, since smaller fonts might affect people with low visibility. Still, if the submission pages work right, then why can't the blog post be the same?
  2. This one is much more significant. The line spacings in the blog post is way wider and unnecessary. In the submission pages, the line spacing's width is from about to that of the line itself, while it's about the size in the blog posts.

Why am I complaining about this? How could the codes being presented in more spaces discourage people from reading it?

Let's make it simple. The model solution, hence its name, is something people would look at, not just to learn about the algorithms for the problem, but also coding experience from the problem setter himself/herself.

Let's assume every setter has for oneself model solutions which are nice, short and clean (as far as he/she can achieves). The short quality is ruined critically by the formatting. Imagine it, the source code is made one-third longer than usual, causing the hallucinogenic effect that makes people more prone to give up reading (since we all naturally feel tired within ourselves to read something long, at some extents depending on each individual). Therefore, the effect and purpose of publishing the source code is halved, and of course, the good efforts created by the setters are poorly wasted.

A solution for this issue can be simple. As I might have stated implicitly throughout the post, there exists two types of formatting source codes, one is worse in terms of UX than another — so why can't we replace it with the better one?

These are my analysis and opinions. I hope the administrators/moderators of the platform will look into this and provide some solutions to improve the satisfaction for both the users and the setters/solution writers.

Best regards.

Read more »

 
 
 
 
  • Vote: I like it
  • +32
  • Vote: I do not like it