Привет, Codeforces!
В 07.08.2019 17:35 (Московское время) состоится Educational Codeforces Round 70 (рейтинговый для Див. 2).
Продолжается серия образовательных раундов в рамках инициативы Harbour.Space University! Подробности о сотрудничестве Harbour.Space University и Codeforces можно прочитать в посте.
Этот раунд будет рейтинговым для участников с рейтингом менее 2100. Соревнование будет проводиться по немного расширенным правилам ICPC. Штраф за каждую неверную посылку до посылки, являющейся полным решением, равен 10 минутам. После окончания раунда будет период времени длительностью в 12 часов, в течение которого вы можете попробовать взломать абсолютно любое решение (в том числе свое). Причем исходный код будет предоставлен не только для чтения, но и для копирования.
Вам будет предложено 6 задач на 2 часа. Мы надеемся, что вам они покажутся интересными.
Задачи вместе со мной придумывали и готовили Роман Roms Глазов, Адилбек adedalic Далабаев, Владимир vovuh Петров, Иван BledDest Андросов и Максим Neon Мещеряков. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.
Удачи в раунде! Успешных решений!
UPD: Так же от наших друзей и партнёров из Harbour.Space есть сообщение для вас::
Привет Codeforces!
Остановитесь на минуту и задайте себе вопрос — каких навыков мне не хватает? Каковы те ключевые качества, которые превратят меня из достойного разработчика в экстраординарного? Я там, где я хочу быть, с точки зрения личного прогресса?
В Harbour.Space, мы ориентируемся на основные технические и социальные требования работы будущего. Наши трехнедельные курсы предназначены для того, чтобы студенты могли приобрести и развить определенные навыки посредством семинаров, практикумов, проектов и тематических исследований за очень короткое время.
Курс Михаила MikeMirzayanov Мирзаянова, Advanced Algorithms and Data Structures, отличный пример такого подхода:
Это, в сочетании с нашей неповторимой учебной средой, обширной профессиональной сетью и нашим кампусом в прекрасном городе Барселона, обеспечивает действительно уникальный опыт обучения.
Заинтересовались?
Заполните форму ниже и получите больше информации о том, как вы можете попасть на курс Михаила MikeMirzayanov!
До скорой встречи!
Harbour.Space
Поздравляем победителей:
| Место | Участник | Задач решено | Штраф |
|---|---|---|---|
| 1 | CSWhisky | 6 | 258 |
| 2 | tfg | 6 | 302 |
| 3 | Sugar_fan | 6 | 310 |
| 4 | jiangly | 6 | 338 |
| 5 | Geothermal | 5 | 195 |
Было сделано 109 успешных и 290 неудачных взломов.
И, наконец, поздравляем людей, отправивших первое полное решение по задаче:
| Задача | Участник | Штраф |
|---|---|---|
| A | nantf | 0:03 |
| B | Denverjin | 0:11 |
| C | Geothermal | 0:20 |
| D | dhxh | 0:10 |
| E | lqs2015 | 0:19 |
| F | duxing201606 | 0:59 |
UPD: Разбор опубликован
I have joined 7 Educational Codeforces Round and 6 of them, my rating went up.So I love Educational Codeforces Round and I hope to become orange after this round.
Wish you good luck~.By the way,this group of people have held plenty of Educational Rounds and did help us a lot.Thanks to them~ :D
I have joined 3 Educational Codeforces Round and all of them , my rating went up . So I also love Educational Round and I hope to become purple after this round .
Wish you good luck too~~
Wish you good luck(run away My rating went up to 1653 in my last Educational Codeforces Round.Wish I can come back to Expert in tonight's Educational Codeforces Round and wish all of you will have a good luck！
I have joined 1 Educational Codeforces Round and in 1 of them, my rating went down. So I just hope to not become green after this round.
2 days later.....
o o f
So this edu round was kind of unexpected. How is your rating now?
CF-Predictor says my rating can be 2101 after this round.
Kind of really close. Hope you will be orange ^^
Mine's 1394. That just sucks.
We expect halyavin will be disappointed in this round.
good problem as usual
if only that was true
It's good, but i can't do it.
What is the difference between these Educational Rounds and others? I have never joined Educational Round :)
Educational Rounds are based on ACM/ICPC rules and there are 12 hours for hacking any solution you want after the contest ends.
In traditional codeforces rounds,hacking is only avaliable during the contest and you can only hack the solutions written by coders who are in the same "Room" with you.Moreover,points of each problem decrease as time passes.
Thanks for your reply, so these are beginner-friendly rounds :) What happens if I have been hacked? Do I lose any points or not?
It counts as a failed submission and you lose points
Sooner or later, if my submission is incorrect (it may pass from pretest but fail on final test) it will already not pass from the final test. So, as far as I understood, this hacking stuff only brings points to contesters who use it.
Thank you for your reply :)
People don't gain points from hacking in educational rounds. Systests in educational rounds consists entirely of successful hacks as far as I know.
Ranking in educational rounds is based on first the number of problems solved, and then the total time used for all the solved problems plus failed submission penalties.
I wouldn't say educational rounds are more beginner friendly than regular Div 2 rounds.
Yes, Don't let the name surprise us :)
No differences.
That's totally impossible. Even the names are different.
Maybe you can find it here.
Good chance to become master :3
Good luck!!
Good luck everyone, and me to become specialist :/
You will never become a specialist.
Good luck to you!By the way, Good luck to me to become expert.
The same as the comment above
I've seen you say this more than three times
You will never succeed if you just say
Seems we're at the same boat. Make the most of it.
Out boat just sank :v
While my friends hang out with their girlfriends on Chinese Valentine's Day, I have to stay at home to participate in this round. Maybe I should see Computer Science as my girlfriend... Anyway, good luck and happy Chinese Valentine's Day~ :D
Now it became a sad Valentine's Day. It seems that Educational Codeforces round broke up with me. (T_T)
Hope it will not be unrated...
I want to become Expert again....!
I don't want to become Expert again, but it must will happen because I ranked 3500+th. QWQ
Don't be discouraged. Come on next time.
Don't worry about it,you can become candidate master again.I wish you will do it in a short time(maybe the next contest).
Wow, I see Benq registered today ... the day between IOI competition day1 and day2.
A good competitive programmer should be able to deal with that kind of workload.
I am so worried because it is my first time to join a Codeforces Round.
Good Luck Everyone!
qaq
good luck and have fun!
Its the worst thing you could do this evening...
OMG I feel SOOOOO SAD for you!
Let's bang this round.
more like got banged by the round :D
What are the links to the light versions of Codeforces? Anyone?__
https://m2.codeforces.com/
Wtf, can you pls speak about some specific conditions of round? Like anti-understandable tasks, queryforces and another awesome things
Раунд просто помойка. Таких мусорных задач я не видел со времён раундов по отборочным на технокубок. Авторы скатились с Эвереста до Марианской впадины и продолжают прорываться к центру земли.
Not actually participating in the round, but I guess a grey or green coder (normally capable of doing div.2 A) would cry when they see this problem statement...
Yupppppp, that's right :). I'm crying...
Lol. I almost cried.
Контест для любителей поработать ручками. Еее
for me contest lasted 15 min. thanks. i enjoyed a lot.
I have seen easy and difficult problems that were fun or boring.
But this round has outdone them all.
And I hate strings!
Imagine having tasks with nice solutions and statements.
"i know im not the only one" — sam smith :D
Educational Round...????
Seriously...???
Well, this looks so much like an education round that I decided to go to bed.
Educational Round is too dangerous to me,my code usually can be hacked easily.I have been hacked for four times in a short time.So,I didn't join the contest.
u good bro?
2 mins before the contest : watching youtube
2 mins after : reading problem A
15 mins after : still reading A
16 mins after : back to youtube :)
2 mins before the contest : watching youtube
2 mins after : reading problem A
15 mins after : still reading A
16 mins after : back to youtube :)
same to me
close enough bro.... (https://codeforces.com/blog/entry/68425#comment-527756)
I wanted your 80 upvotes bro :P
Okay, i understand, that Mike wants to promote his students, or something, but maybe it's time to stop? Come on, CF haven't seen such concentration of shit in one round during all existence. I suggest that Mike should at least have a miser look at the tasks, that are given as 'educational'.
Ofc, rounds from GreenGrape were much more interesting, then from this team now
UPD: Sry for bad english(
Ofc, not ofk
Interesting, not interested
At least you tried!
I guess Codeforces seriously wants to educate us by giving DIV 1 problems in DIV 2..
this problem A really knocked me out
this contest is a bad marketing strategy for harbour space
Stringforces
Are you from future ?
Actually it's 70.
the math person from discord is in the announcement pic, no wonder this round is bad.
Who is he just to be safe in future rounds ?
Seems like Div 1 :(((((
Только взял золото на межнаре и тебя уже цитируют...
Stringforces??
The setter did a typo while writing division, he actually meant div1
I give up.
Not enough string power
I guess, I can't solve any of it before the Editorial :(
How on earth is this round educating??
In problem A there is quote from Wikipedia, there might be some people don't know about! and now they learned it. is that not educational? xD
I doubt they learned stuff specific to the problem. Quoting from the quote : then the string whose first letter comes earlier in the alphabet comes before the other string. 1's and 0's are not even alphabets!
Stringy round = hard round (?)
Makes me wonder, if a true Mathforces round could be held unrated in a seperate series, and this one, basically a stringforces, cannot; then what's the issues?
In this round the question has made in the upside-down universe that's why it seems hard in this universe
Is it serious for us div2?
I think I have crippling depression.
It's more like div1 difficulty, RIP Rating :(
When a sensible contest with legitimate problems will be made
Negative, LOL.
It was really a UNIQUE Educational Round.
I hope it will never ever repeat
This contest is so hard for Div2
But if this round is too eazy , how can we say it 'educational'?
I think we can get more knowledge in a little more difficult round , right?
This round was majorly implementation based. Even the I/O was to be taken care of.
Очень приятная С-шка, спасибо
The most difficult EDU round
This educational round was terrifying to me :<
Да, я понимаю, может вам надоело делать однотипные образовательные раунды, но сделать раунд таким, нуу... думаю многим это не понравилось. В чем смысл в строковых задач? В чем их поучительность? В их реализации? Ну не знаю.
Извиняюсь за возможную резкость, но, немного припекло.
Во-первых, "строковых" задач была одна штука — E. Остальные не требуют знаний строковых алгоритмов от слова совсем.
Не соглашусь и с тезисом: сложные в реализации. Авторские решения по первым 4 задачам суммарно чуть больше 150 сток — есть множество действительно строковых задач, где 150 строк — это только подготовить всякие суффмассы, LCP, Sparse Table и т.д. Я понимаю, что мерятся строками — такое себе, но я не знаю как простым способом оценить такую субъективную величину, как сложность реализации.
Если Ваши решения действительно сложны в реализации, то, возможно, этот раунд действительно образовательный для Вас.
Вы меня неправильно поняли. Дело не в строковых задач. Я ничего не имею против этого. Меня смущала всего одна вещь — сплошная реализация. Просто, мне кажется, что в образовательных раундах обычно должны давать задачи на базовые алгоритмы. Да, задача E была отличной. Но остальные задачи требует больше умение программировать или придумывание решений нежели понимание базовых алгоритмов. Я помню, свой первый бинарный поиск и свою первую динамику в контестах я написал именно на этих образовательных раундах. Многие смущаются на то, что многие задачи в образовательных раундах стандартные и легкие. Мне кажется все должно быть именно таким. Ведь начинающим не хватает именно этого — уверенности. Решая стандартную и легкую задачу начинающий обретает уверенности. По себе знаю это. Майк Мирзаянов написал, что задачи были интересными и конструктивными. Я согласен с этими. Задача D мне очень понравился. Но я думаю, что такие задачи должны давать на обычных раундах. Ведь задачи на реализацию и конструктивные задачи не дадут начинающим много пользы.
как недавно писали, раунды не могут быть образовательными. Самое сообщество на кф убило образовательные раунды. Раньше это были не рейтинговые раунды, поэтому мы мог просто дать самые обычные задачи напишите бин поиск, напишите ахо-корасик, напишите small-to-large и тд. (многие темы я тоже впервые встретил и изучил на этих раундах.)
Теперь так как это рейтинговые раунды, в них нельзя давать обычные задачи, которые по факту раньше и были обучающими. Теперь это что-то среднее между див1 и див2 с форматом icpc.
Я не знал про это. Теперь понятно в чем дело. Вот почему я часто встречал знакомые алгоритмы в самых ранних раундах, а последующих нет. Ну тогда значит почти нет разницы между обычными и образовательными раундами.
Я не говорю, что слишком сложная реализация или прочее. Задачи были несложными. Дело не в этом. Раньше, я если захотел узнать что-то новое всегда участвовал в виртуальных контестах на этих образовательных раундах, зная, что встречу что-то новое, еще не встретившую раннюю алгоритм. И LCA, и метод двоичного подъёма и СНМ я узнал благодаря этим раундам. И вычислить мат. ожиданию в сложных задач тоже научился благодаря вам. Ведь обычно именно вы дадите задачи на теорвер. Я просто хочу чтобы вы чаще давали задачи на базовые и продвинутые алгоритмы, чтобы начинающие узнали новое.
why first three problems were so much harder than what we used to see in previous div2 rounds.
They weren't really much harder, but A has shitty statement and B, C has shitty implementation
When will the test public
Worst Educational Round to me.
This contest sucks. A and D are a bit interesting, but B and C are just like shit, especially B. Implementing is much harder than thinking. E is so standard that who knows AC automaton would easily solve it.
Well I know E is good for educational rounds, but I really disgust such problems like B and C appear in Edu rounds.
I could have slept an extra 2 hours instead of getting owned by this round :(
I hate problem C just because its code will be so long,and I cannot finish it.Isn't it write one thing for 4 times?
A was tricky for me .. instead of length of x and y are <=100000 i misunderstood as f(x),f(y)<=100000
Sorry to say, this is the worst contest I have ever participated so far!
i think (and i wish :D) it will become THE most "not liked" contest announcement of all time.
Lol, I think, arsijo s round is the most unliked
which one?
Round №571 div.2 from summer camp
Round started...
Thinking on A...
20 minutes later
Okey, I cannot write any solution, that I can prove. Let's write some shit.
Samples passed
Submit
OK
In problem E, what is the intended solution's time complexity?
Linear.
could you explain your approach...
$$$a[i]$$$ denotes the number of strings that can be matched ending at $$$t[i]$$$, $$$b[i]$$$ denotes the number of strings that can be matched beginning at $$$t[i]$$$. So the answer is $$$\sum a[i]b[i+1]$$$.
How to calculate those two things quickly? Can be done by two Aho-Corasick Automatons. One contains all $$$s$$$, the other contains all reverse strings of $$$s$$$.
Author's solution is $$$O(n \sqrt{n})$$$. You can write whatever you can.
this contest was implementation heavy , could not finish C. Please problem setters, consider duration of contest proportional to difficulty!
So the problems in edu rounds are not sorted by difficulties?
I think problem B & C are too difficult for div2 b c....
Why AC-Automaton got TLE on test 5?
58456132
You used a violent jump fail pointer in the quary function.
Ohhhh...Thank you!
I should quit before submit anything.
But the better thing is I can join Div.3 now LOL
Horrible EDU ever
seriously, what is this B?
also A is hard to read :(
B is just a simple implementation problem. Sometimes you just have to spend some time reading the problem's statement and then spend some time coding some basic stuff. А is also about reading the statement. Why the fuck do you consider smth like "Pls output YES if n is odd and NO otherwise" as a nice problem for A?
But low-skill kids prefer to write shitty comments instead of upsolving because it's so much easier, right?
what you mean "low-skill kids"? why are you that aggressive?
this picture is just joking about my feeling on B : /
and in round I skip B and solve CD, cuz B is too hard to read(for me)
in fact, to me, I'm just can't read out what A,B want to explain.
and I solved that B after round in 5min.
A&B 's coding time is shorter than 15min for me, but too hard to read
I spent near 1hour in total on reading A,B and understand them : /
well, ok, it's just my english noob , ok : /
and personally, I think this round's problem it self is not bad...
but the statement is really hard (at least for me : (
I think a good problem should take more time on thinking but not reading :p
Actually, your meme is a nice one, I liked it, should’ve point that out directly. I just upset by the fact that people downvote nice contest. It’s kinda sad, you know. Pls register some fake accounts and upvote the blogpost back.
and also
Why the f*** do you consider smth like "Pls output YES if n is odd and NO otherwise" as a nice problem for A?I didn't remember that I said things like that :p
The Education Round requires a lot of thought.
It doesn't seem to want to be passed on as a simple idea.
But ranker's code is simple!
Educational StringForces Round 70 (Div.1)
owob
The Problem D is just a easy problem, why did u put it on D?
The Probelm E is also a easy ACAM problem, why did u put it on E?
The Problem A is not a div2-A...
I use my another account MtOI to join this contest (just for rating),
at first I wish to become Master, but the result is terrible.
I feel very disappointed for this contest...this contest does not fit many people.
Hey. I want to share my thoughts about this round and your reaction to it.
I agree with the opinion that the first problem has an unpleasant wording for beginners. If I were a round writer, I would try to do something with it or replace the problem. However, I do not see anything particularly terrible in this problem. Moreover, it is in an educational round that one can more likely expect a problem that will teach you to read a formal mathematical statement. The implementation of the solution is really simple, I think that many participants were too lazy to delve into its statement.
The second problem is very well formulated, has a short and understandable solution. It can be interpreted as dynamic programming or even as some natural idea (brute force). Perhaps this problem is difficult for position B, but it is far from div1 level, many div2 participants have solved it. It doesn’t require any specific knowledge.
I did not delve into the following problems, but it seems they are fairly distributed in complexity, using different ideas (I noticed not only strings, but also constructive and data structures).
I note that all the problems were soundly formulated and worked out by the authors: they contain examples along a statement, notes for examples from the statement. The number of questions about statements in this round was very small and there was no need for corrections in the statements. There were no troubles with the correctness of tests or writer's solutions. I believe that the writers have missed a bit with the complexity of the first problems and their attractiveness for beginners, but nothing more.
The team of writers of the educational rounds really delights me with their productivity, stable quality and performance. I am very grateful to the guys for their work and contribution to the development of the community. They have prepared a huge number of interesting problems and continue to do so. The vast majority of educational rounds are very good. This round was not ideal, but preparing rounds is creativity, this happens.
I strongly disagree with those who wrote sharply and disrespectfully about this round. I would like the website community to be more able to appreciate the efforts of those who work on a content and forgive mistakes.
In my opinion, all the problem (I mean, at least A-E, which I came up with the solution) was easy to understand. Also, if you choose good way, implementation can be simple enough and easy to debug. I don't have agreement or disagreement about the difficulty or the problem order (I think it's far more harder than writing a problem and the ability to estimate the problem is very special skill). But at least, I think there are nothing to complain about the quality of each problem. I hope that writers won't be disappointed and hold such a contest again!!
In my opinion, these problems are valuable for someone new to Codeforces contests, in which you need to think a lot. These problems can improve one's implementation skills and thinking skills greatly. However, contestants usually estimate a contest with the time they need to come up with the solution and solve each problem, especially problem A and B. These problems worth doing, but they are somehow unpleasant for a Codeforces contest, for problem A needs time to think, and problem B needs time to write.
Лучше бы не писал этот раунд(
it was the best contest till now. loved it to solve one question.
People are getting triggered just because A was slightly harder than usual :thonk:
Congratulations for the revival!
Is it rated?
why not?
Because the server ran out of steam?
choo choo
It feels like my girlfriend left me during the maintainess of Codeforces, though i don't even have one.
So what was wrong with Codeforces?
So, when will we have system testing? Or is it done before?
UPD: I've just seen the announcement. The Open Hack Phase have been intended.
Не сказал бы, что раунд плохой. Только у него есть некий налёт начала нулевых, я даже пустил скупую мужскую слезу.
Is the hacking phase over?? Or will it be extended?
It will be extended in ~10-30 minutes.
Looks like someone is not happy with this round. And he hacks...
The website
Wait for becoming master all day . And seems it needs another day for open hacking QAQ
Auto comment: topic has been updated by awoo (previous revision, new revision, compare).
че за бомбеж?нормальный контест
Why is the editorial published when the open hacking phase is still running?
By the way, this is one of the particularly good round, where every successful attempt to solve a problem gives great sense of accomplishment.
What is wrong with editorial published while open hacking is running?
To hack a problem, you need first to solve it correctly. with the editorial published, hacking becomes easier because everyone knows the correct solutions.
Isn't that a good thing?
Well, that's relative. For me, at least, I like the part of solving the problem correctly first to be able to hack other solutions.
:( I very hoped I can become blue. :( but so sad with Education 70.
Got TLE on problem E during the contest because I used a map to count number of occurrences of numbers in range [0,2*10^5]. I hate myself :(
What do you mean? My rating? It will go deep for sure
This round had a good distribution between problems (by numbers of contestants solved each one). Sadly, I performed so badly, feel a bit sad {'-'}. Also its a lovely curve or maybe Im wrong?
How I thought of this round:
Problem B was a high quality problem. Problem B for a Div 2 B is not so high quality.
Meanwhile we'll say "sakib kala parena" :3
why one of the 2 solutions give tle although it has same complexity!! (https://codeforces.com/contest/1202/submission/58463769) https://codeforces.com/contest/1202/submission/58463646
https://codeforces.com/contest/1202/submission/58463646 https://codeforces.com/contest/1202/submission/58463769 why one of the two solutions give tle??
Your size of array is not big enough.
hey really thnx!!!
You know what? I don't care contribution now. I just wanna say the contest is terrible.
Did you ever seen ANY Div.2 A like this one? Multiple queries, length up to $$$10^5$$$, are you serious? It's Div.2 A, not Div.2 C or even harder!
The same problems on B and C, I'm not saying they are bad problems, but they are just too complex for being the first three problem in Div.2.
For problem D and E, their idea are similar to other problems. I swear I saw the exactly idea of D(add $$$\binom{k}{2}$$$ to get any number) in other problems. And problem E's first key idea is the same as CNOI 2016 D1T1 "Excellent Partition". So I think these two problems are not good-quality enough.
No Codeforces contest is flawless, but this one is so awfully flawed!
Yes, looking at feedback, it's clear now that we (personally, myself) overestimated our participants. It seems like we need just one more task before A.
But for me, personally, there are no problems with current D and E. Problem D was not hard and, I believe, you can invent the solution without knowing it beforehand. And problem E appeared 3 years ago — I think, it's not critical.
I agree that originality shouldn't be a concern for educational round. On the other hand I feel that the right order for BCD should be D — B — C.
The topic is not too difficult. There is not much problem with the number of questions.
I don't agree on your opinion, I didn't paricipate in this contest, but i have to say, this contest is not bad at all!
You say the problem is too hard, so you don't like them. But in fact, there are still up to 3000 people solved it.
What kind of Div.2 A do you like? A 500 points problem? Or a even 100 points problem? Codeforces is not a place for you to practice the basic C++/python/Java skills.
And the difficulty distribution is also good in this contest. Number of accepted people on each problem: 3441-1359-375-865-71-6, every two problems can differentiate two colors. Do you like a contest with number of accepted participants:10000-10000-10000-100-1?
I understand your disappointed feeling when you opened the A, B and find yourself can't solve any of them, but it's not a fair reason for you to complain that this is not a good contest.
If this contest is just lacking in a 500/600-points problem, it's still a good contest.
In the end, i still want to add one point, the writer spent thousands of time on this contest, what would he think if he see you complaining the contest just because of the problem is too hard for you? Have you ever prepared a contest? I really don't understand why there's so much downvotes of the blog and so many complaination of the problem.
I always agree that Codeforces is the best CP platform all over the world, but i'm very worried about this people who downvote the blog or send their complanation just because the problem is too hard for them.
I didn't say the problems are too hard. I'm saying the problems don't match with their ID. If this is a Div.1 Round instead, I may say those problems are slightly easier.
I've never seen a Div.2 A or B like this. As you can see, problem B here has a difficulty of
1700, which is close to regular Div.2 D. And problem C's difficulty is shockingly even higher:2100, it means in general, those who solved Div.2 C is able to get to level Master, isn't that ridiculous?I wish the following contests can be more "regular", and their problems can be "close to normal-difficulty problems", but not like this one, one of the most annoying contest, Educational Codeforces Round 70.
I agree that this contest's problems' difficulty doesn't match their ID, but absolutely it's not a fair reason for the blog to get so many downvotes and so much complaination.
You could just imagine this is contest without problem A. Getting the order of problem C and problem D wrong is a slight mistake. You could be polite and comment under the blog and say: "We want a easier A, and wish the difficuly of the problem match their order." istead of say:
one of the most annoying contest, Educational Codeforces Round 70.
And, this contest neither contains a "broken" problem nor leaks problem before it started. One shouldn't speak so impolitely to the author, I sincerely hope that those who said this contest "is the worst ever" can apologize to the writers of the round, for their hard work on the contest, for their hark work on the past all educational contests, for their hard work on making Codeforces better and better.
orz jgh
orz.
Check it yourself, and also Comet OJ — Contest #9 & X Round 3.
Codeforces Round #564 is mainly prepared by me, I poured time and energy into it. After that, I learned how hard it is to prepare a high-quality round, and also, how important it is to prepare a high-quality round.
Because you "spent thousands of time", you should make it high-quality to be responsible for yourself.
Because here is Codeforces, "the best CP platform", you have to make it high-quality to be responsible for thousands of participants.
One reason for CF to be "the best CP platform" is that it guarantees the difficulty of problems, and we can know a problem's difficulty by its position. Problem writers should follow the standard of difficulties.
Again, efforts can't win respect without taking responsibility.
In addition, good problems can form a bad contest.
Also, a list of logical mistakes:
Usually, there are more. And you should also consider the time people used to solve it.
We want problems in normal difficulty, not too difficult nor too easy.
I can't see any reason for PinkRabbit to like this distribution.
I think he could solve it, but found it was harder than usual.
I think you meant "you can't solve them", and that's not true. We say "it's too hard" to mean it's harder than usual.
Discussed above.
When will the system testing start?? Will it take one more day :XD
The objective of Educational rounds should be to educate. One can't learn much from conventional Div2 A and B difficulties, and to think of it, real learning begins with discomfort which one slowly conquers. I think the contest was just fine for serving this purpose, since the techniques it covered are standard-ish while being slightly disguised by more involved problem statements. One may argue against the high amount implementation of B and C, but hey, learning to implement long solutions with brevity is also an invaluable skill. For example, I realised after the contest that I could simply have used a (multi)set to query suffix maximum and minimum on the fly instead of dealing with four separate cases in suffix maxima/minima of x/y. I could only have realised this mistake in an implementation-heavy contest.
In short, Educational rounds are perfectly fine as long as they introduce relatively standard techniques.
I think we say the round is bad doesn't mean we disrespect authors.I like these problems.I just think they should be replaced in better positions.(A->div.2B,B->div.2C,C->div.2D,D->div.2C,E->div.2D).
I think C can also be done by efficiently brute forcing with the help of Range min/max lazy propagation segment tree. That would be overlkill though. Correct if I am wrong.
There is no need for lazy propagation, you can precompute prefix sums and use those values for the min/max segment trees.
I used ST since I didn't want to think the linear solution xD
58444732
maybe it's wrong to send that comment out.
I'm so annoyed at beginning and send the to comments.
but infact I don't want to argue like that at beginning. sorry.
maybe it's I have not sleep for 36 hours so my brain dead...
I'm idiot... made a lot of spam at here... sorry...
First of all, I'm very sorry about what I did. You see, I'm just a pupil. I learnt to use Codeforces just one year ago. I don't even know I will appear in PikMike's blog! I become happy only because "Successful Hacking Attempt". I do this just for fun and I hope you can forgive me. Ignore me. zdw1999 is the best hacker. Thank you. I'm really sorry.
I am so sorry for being normal with you
seems it's just some misunderstanding
sorry for take such long space
I am so sorry for being normal with you
deleteI am so sorry for being normal with you
I am so sorry for being normal with you
I've learnt many things from this round, it improves my strings manipulation. Thank authors
is the list of best hackers correct? for example, it's showed that awasd has only 3 successful hacks, although i can see he made 5 successful hacks.
It's really weird but two of the hacks made don't appear as hacks but as Wrong Answers on test 11. Anyways, if only the 3 hacks count shouldn't I be on the 5th position? :P (I made 4 hacks Lol)
Hmm, I retrieve that list from CF api. Looks weird.
I guess I can just hide the table for this contest, maybe I'll fix it before the next one.
It's too hard!!!!!!!!!!!!!!!!
I am former candidate master and I can't solve A. Would tourist solve A?