Hello, Codeforces!
Paul stingray Komkoff is my hero! He found some issues in the network configuration. The most important of them was about flow control auto-negotiation: in case of our network routers the number of dropped packets reduced in times. Thanks!
To be sure that it really helped to fix the issue I ask you to take part in Testing Round 16 (Unrated). It will start on May/07/2020 17:05 (Moscow time). Probably, it will contain 3 easy problems which are not prepared for now (I'll use some old problems, I think). The only reason to host the round is to check the system under a load. It will be an unrated round.
I am upset about what happened with the last round. Once again, I apologize to both the participants and the writer, coordinator and testers. I wrote Monogon about the incident and apologized.
I am sure that the only way to absolutely prevent unrated rounds is just don't host them. And this is not my way. The most popular rounds were hosted without noticeable technical problems. And I'm sure the main records are yet to come. I ask the writers and coordinators to look forward with optimism and try to please us with problems.
Please, join to the testing round. See you!
— Mike.
UPD: Thank you for testing! I think the system worked great. It seems recent reconfiguration improved system performance and stability. We have some rare "Judgement failed" after database update (I'll try to fix them asap).
Thanks Mr. Mike, for your relentless effort to make this platform better during these harsh times. Hope everything works out.
We will gladly participate in the testing round :)
It is sad to see that when people need Codeforces, they participate in huge numbers. Yesterday's contest had total of 28k registrations. Now when Codeforces needs people, they just don't bother to contribute as there are only 8.5k registrations till now.
just submit each solution multiple times
I am sorry that u feel this way but i did not check my mail until the round was already over. I wanted to be a part of this too :(
You can count on me :)
It is nice to see that Codeforces community is making some good efforts :)
This quarantine time we expect more contest.Why my comment too much down voted don't understand.
I guess it's because the exact same thing has been said countless times since the quarantine started XD.
May be.
Everyone should try to participate. Codeforces is getting better in this quarantine. <3
Make codeforces great again together, <3
did you put this comment for increase your contribution ?
even you don't submit a single attempt in this testing round .
tahsin_protik
Give him the benefit of the doubt — he might have had legitimate circumstances.
I didn't have stable Internet connection, I wished to participate! Don't spread negetivity in any community!
Feeling sorry for Monogon but gonna remember him for a long time because of the issue :)
Thanks, Mike.
The plot twist is that halfway through, this testing round will become rated when all goes smoothly. :)
In all seriousness, I think this is a great idea, and I wish for upcoming contests to have better luck when it comes to technical problems. I admire your dedication to fix these issues.
Maybe we will have blindfold rounds too in coming future.
All the submissions will be judged after the contest, give your best shot.
That's what TopCoder does. Lets shut CodeForces and make TopCoder great again.
are you serious?
aryanc where c="chutiya"
ignore him he is mentally retarded .bro look for a doctor in jodhpur. his (aryanc403) most of comments either on codeforces or codechef only makes people sick.
0 My father is a well-known doctor in Jodhpur. Feel free to consult him for me. But next time make sure to do your homework.
1 Not surprised with back to back comments within 1 min and personal abuse and same no of upvotes. I'm pretty sure the same person operates both accounts and is upvoting himself using his alts. 650iq and saurabhkumarfx
2 If you were just angered by the fact someone told something to your favourite website then dude gets a life anyone can just come and manipulate you due to your anger.
3 As far as that comment is concerned that was just an orthodox soln to an out of the box solution (presented by BadduCoder) which literally meant just go to topcoder if you want this.
4 "his (aryanc403) most of comments either on codeforces or codechef only makes people sick". My comments are sick but my contribution here is +120 but your both account has -20 each. Much wow. Nice maths. No doubt why your colour is....
that so called out of box thnking made u say both are my accounts?? i am intrigued seeing your maths.But your numbers will fail soon.
haha..i was expecting this comment of yours about the color. Well your color just shows that you have invested more time in coding than us and nothing else. Secondly, apart from coding try to learn how to live a social life, bcoz from your comments i can surely find out one thing that you got no life bro, go make some friends and be happy.
Ok. :).
P.S. — I wrote one more thing apart from colour do read that.
do not be ecstatic seeing your color .Just like you said I have many accounts so i might have better color than u on my original accounts on both platform or May be whatever you have achieved or will achieve in your lifetime using your master color some newbie have achieved more than u till now only .(newbie) does not mean to be disrespected or judged because of their talent because they might have different interest and just learning some basics for fun .And i am sure people like u only clear comapanies coding round and get rejected in interviews finally.So learn some other things also. Being master after slogging like u for years does not make sense and does not make u special and many newbie achieved more than u in their fields in less than that time.
ignore him he is mentally retarded .bro look for a doctor in jodhpur. his (aryanc403) most of comments either on codeforces or codechef only makes people sick.
If you need an anonymous account just to abuse people and get your voice heard. Then let me tell you you are much worse and sick than what you claimed I am. I at least use the same account to say whatever I feel and everyone knows what I am saying and then they use their judgement to make opinions about me.
I wanted to use one specific word for you —
Coward.
sure lets assume i am coward .But do not forget atleast i respect my original color and do not use that color to abuse codeforces like u and on the other hand u learned so much from codeforces and urging people to leave this site when it is going through hard time ???? this is what called traitor and u should know traitor is more shameful word than coward. DO not forget u owe significant amount of gratitude to codeforces and u are betraying it after getting your proud color so called "master" which u are by the way using to show your achievements as well.
Bro, this is hilarious. XD.
saurabhkumarfx, don't take jokes/sarcasm so seriously.
"Being master after slogging like u for years does not make sense and does not make u special and many newbie achieved more than u in their fields in less than that time."
What the heck ? Are you saying if someone takes more time to reach a color , he doesn't deserve it?
Bro , do you even realize how many years most reds have trained to reach their level?
So now if a prodigy comes and becomes a LGM in just one year from scratch , will that mean other LGMs are worthless ?
Some more relevant info : aryanc403 has taken ONLY around 3 years to reach so close to red , and you think that's "slogging like u for years" ? Are you fking crazy? How much faster were you expecting him to be ?
Wait , do you search things like "How to become LGM in one month?" in google? XD
He doesn't deserved a reply. I realised that too late. It's difficult to explain to the kids that some comments are never meant to be taken seriously.
And I got equal no of downvote on it within the same duration. Wow. One more comment just to get more downvotes from your alts.
Thanks but No.
Unlucky that your round was unrated. I really enjoyed the problemset!
Is this test need i crazy submit but not must be "accepted" ?
I think yes. It's just testing the codeforces system.
Monogon's problems were really a bit different and so interesting. I'll be waiting for problems from him.
Is it possible to write some stress test for CodeForces? The test could be like:
Ideally, I think we could run this test 1 hour before every rated round and immediately know if there are issues with taking too much load. This should make it possible to detect when the site is unstable and give us a chance to postpone rated rounds.
I'm sure there are many bored devs (like myself) that could code this up in a few weeks :)
Mike actually has quite a few stress tests, but in this case it didn't help because the issue has only manifested itself recently and it was likely triggered by some other machine on the same network (or even a misbehaving network switch). Fortunately now we know which metric to monitor and we won't be surprised by a sudden failure of this kind.
Thanks MikeMirzayanov for your problems.
They are very interesting.
Was waiting for that "The rounds must go on" line, I have to say i am disappointed.
Hope that Round 640 won't be unrated. If both of the current rounds were rated, I'd have been 2700 :(
As an author I'd also like to see everything is fine. But in fact we are considering delaying the round if such issues may probably happen again in the near future. XD
The simple fact that these rounds were unrated makes their results unreliable. I've also had some great results when enough people decided not to bother competing.
We should participate in large numbers in testing round and make codeforces great again. Good Luck!
Thanks Mr.Mike again,we will glad to participate this testing rounds,and wish the codeforces better and better.
Mike, thank you all the time. We woule love to do that. Hooray
Codeforces Round 639 (Div. 2) really deserves to be rated :)
Why am I seeing so less registrations? Because I think we had no problems upto 10k registrations. So until more than 15k registrations are there , I don't think we will really be testing codeforces' vulnerability. So please do participate.
Will gladly participate! Thanks a lot for this amazing platform Mike!
ok
What is the film that this meme template is from? (thank you in advance)
Person of Interest, episode 4x10 — The Cold War
As a huge Person of Interest fan, I approve of this comment.
It would have been better with 4 problems equivalent to div2 B, C, D, E, I think. Anyway, will participate in the testing round
I think for testing it would be better to have all problems pretty simple like div2A or even Div3A as the target is not to compete but to stress test with many submissions. If you add harder problems you would get smaller queue which is not the target of stress testing!
This testing round deserves more than 15k participants, just like what normal div2 rounds do these days, or the testing result won't be much persuasive. Everyone looks forwards a better Codeforces, especially my friends and I, who has made an effort on preparing Round #640. So please register for the testing round if you can. Hope everything the best!
Happy to participate in the Contest. Will the First question be Watermelon ;-)
Turns out it is not as difficult as you mentioned.
If this is because of server load, maybe CF can start to limit the number of participants to something like 15k participants. I am not sure but I think TopCoder also limits the number of registrations for contests to a small amount.
If stress test is what Mike is going for, I think "the more, the merrier"!
I was not talking about the testing round, but contests in general.
Thanks mike for your effort by providing such a beautifull platform for competitive programming. Although i suggest you should see for the matter of excess crowding on site while rated contest to respect the efforts of contenders and contest organisers. one of my suggestion is -you should close all other activities on site while official rated contest is running.
Let's be the part of the history by our spontaneous participation and make Codeforces great again! Thanks Mr. Mike for your effort.
It was actually frustrating for us when we saw the big queue during contest time even though this contest was delayed for fixing bugs. Still hats off to your effort CF team. Hoepfully today's contest will be a smooth one!
keep calm and submit a code
Thanks to Monogon for the round. The tasks were very interesting. I hope everything will be fine next time
After increasing the participant of div-2 & 3 (24K to 26K ) cf might update their server request bacause before 2/3 month cf have only 16k/17k participants, now its time to upgrade cf server
I'm sure they never considered this...
Is it just me or the world is getting crazier out there :) Edit- It was just a joke and no offense intended to anyone. I greatly appreciate the author of codeforces to give us such a brilliant platform to code and for creating such a helpful community.
It is just you.
Good one. Lmao :-D
I will participate too.. and try submitting like crazy.
And hack crazily!
I hope that after fixing the problem, Codeforces will create more contests, as a compensation for Codeforces lovers. Div3 is a good idea right?
Never fear !! The vizard is here All the best for the round.
If you can,Please register so that codeforces can find the problems and solve them.
MikeMirzayanov if you wanna check the extreme case put at least 1st problem easiest. Kind of "sum of two numbers" or something like this so that everyone submit it instantaneously within seconds and hence it will result in largest overloaded queue possible.
would like to thanks to Mr, Mike for his efforts in last round and i appreciate the idea about 1 hour unrated contest. I will surely take part in this contest.
Thanks Mike for this wonderful platform and your efforts to make it better.
I think this contest should have as most participants as possible. If so then the testing round will be successful and Mike can be sure that It is okay now.
so participation is our responsibility now.
HEY FOLKS WHAT İS 7K REGİSTERED ?? We have to increase this much more and be a lot of people (like regular rounds) otherwise the testing round has no meaning, right?
let's wake up and attack the judging. let's see has it fixed? I hope it has improved Thanks MikeMirzayanov for your strive, although if it has not improved!
To make up for the low participation I suggest we all spam submit with any code every minute lol
That sounds great. I hope Codeforces is getting better and better.
I felt bad for you. During every contest in this quarantine something bug issue came. Hope this time there is going to be everything solved! Good luck.
I'll try to enter Guinness records for 'the most submissions in one Codeforces round' .
I hope there will be a load or it won't test much.
Exactly, I expected to see easy problems with large input or large amount of processing needed, with lots, perhaps hundreds of test cases. Instead, we got three problems with a trivial amount of processing. This round didn't test anything.
Making more submissions, would you like to join me in the coding challenge without compiling? Just thinking is interesting!
Very few registrations in comparison to last round! Where are the rest of the participants who felt bad for the last round? :(
Hope test round will be successful. It is beneficial for both sides. Because no problem setter wants their round to get through troubles and no participant wants their preparation to go in vain. All the best.
Please submit lots of submissions, this would make this contest have a high load, and get better results.
Yeah I think its the only way now, I thought more people would participate :(
This is the only round where my code has a lot of bugs is useful :D
Is it rated?
Read the announcement.
Rofl, you know?
is rating contest?
Please provide ranks though.
Probably it would have made sense to add much more problems (even simpler ones), so that even a relatively low number of participants could generate lots of sumbissions.
Im so happy that everything works great! Congratulations!
As it is a testing contest so we should make a worst case(a lot of submission) :)
Thanks for the contest <3
Locked problem but cannot see others code. I am trying to hack. Should I hack blindly?
It is testing round, try it ^^
This could've been a cute div3.
i think too easy even for div 3. but yes, B and C were pretty nice!
I solved all problems, cant we make it rated?
Well yes but actually no :))
Anyone else or just me who received "Judgement Failed" verdict in problem C and suddenly after a minute or two it changed to "Wrong answer on test 2" ?
Althogh i solved all problems, but CF predictor tell me that my rating will go down. X:) (just for fun)
So on the bright side , codeforces will work better than ever now?
How to solve A? I think it had something to do with FFT but I couldn't get anywhere
You should try
DPandShortest Path,as well assegment treeand etc.Well, FFT is definitely not enough in this case. Try transforming it into a graph problem and then finding some flows.
I think you got it wrong it was to be done by convex hull trick with matroid transform
I solved it using squirtle watergun algorithm
About which problem are you talking bro ?
I'm sure you're not talking about problem A of this testing round...
This is a tough one.
Let dp[i][j] be i + j. Then dp[i][j] = dp[i-1][j-1] + 2.
Another solution is to observe that add(a, b) = add(a, b-1) + 1 and so you can solve the problem recursively.
I can't think of any solutions simpler than that.
Are u serious? I think fft is overkilled here. I used 2 arrays to store a and b in binary base. Then just simply did greedy.
Got AC with wavelet tree.
You can also do Matrix Multiplication for a simple solution. https://codeforces.me/contest/1351/submission/79303363
Well constraints were too tight I think machine learning can do some good....
Prob A was meant only for Red coders. Don't waste your time on it. I am waiting for its tutorial...xD
Judging System got slow again at the last minute?
UPD : it's ok now
How to do C?
Maintain which point you came from and where you went for every move, store them in a set to check for repetitive.
Hi! I solved it after the contest but can you help me if my logic is right? I made pair of each and every point I have already visited and store it in a set. Then I check if destination point is in the set. Is this the right approach?
That was my solution initially, and it is wrong. The problem asks to check for visited segments, instead of points. So if you went from (0, 0) to (1, 0), and then at some point went from (2, 0) to (1, 0), these two are considered different segments and take 5 seconds each, although they share the same destination.
Try taking a map<pair<int,int>,set< char >>m... store the visited points in pair<int,int> and the direction from which it is visited in set< char >. Then see if your destination point is in the map as well as check if it was visited from that direction ...hope that helps...
there are 4 directions to come at a point but this set will only be able to store one
how to check that then?? thanks in advance
Its set< char > so it can store all the four directions... I don't understand your point..?
https://codeforces.me/contest/1351/submission/79305532
Thanks! That is an amazing approach with a minor modification. I just hardcored the solution by making a set of pairs of start and destination and destination points. Something like
set<pair<int,int>,pair<int,int>>. Then I just check if the current start and destination points exist in the set as (start,destination) or (destination,start). I was not familiar with pairs till now but figured it out after the contest. Here is a reference to my solution.No need to thank me....we are all here to help each other out.
Can you check what is wrong in my solution https://codeforces.me/contest/1351/submission/79353675
Try this: WNES
Works fine, gives 25 as expected
The correct answer is 20, and I was expecting your code to give 16 hmm
When will the editorial be available xD?
I m wondering what would be the editorial for prob A..xD
How to solve c? What is the concept used
You need to store tuple of four values (fromX, fromY, toX, toY) in a set, when you insert a new tuple but it already existed time++ otherwise time+=5.
So, this is a testing round for the feasibility of div.4 round?
Never seen that div.4 round but my eyes felt good seeing it :)
You actually predicted this to happen.
wtf... Mike! I’m just joking!
IS codeforces running in a cloud server? If that the case, why not scale-up the resources?
.
No.
It's possible to make a rated round unrated, but impossible to make an unrated round rated.
It is possible but that will not be fair.
Can't I submit the solutions again after contest?
You can.
You can't submit during system test.
How to solve B?
Just add non-equal sides of two rectangles and see if it matches the other side of rectangle.
Eg.
l1=3,b1=1 and l2=3,b2=2(l1,b1 = length and breadth of 1st rectangle ans so on)so check
b2+b1 == l1In other words if summation of two different sides of rectangles should be equal to size same as the common side of rectangle.
For a square $$$a \times a$$$, it will split into two pieces after the operation. Let's assume that the size of them are $$$x \times a$$$ and $$$y \times a$$$. Notice that $$$x+y=a$$$ and $$$x<a, y<a$$$. So the greater one in each pair should be equal. And the sum of the smaller one is equal to the greater one.
max(a,b) == max (c,d) && a + b + c + d == 3*max(a,b)
When is the next div 3 contest? I want to participate and I wnat problems for my level!
When your only contribution on CF is because of the memes you upload.
Why where the problems so hard?
I think CF can provide a simple trial problem before each rated round like 3-4 mins before. If you want to participate, you have to solve that problem. This would lead to a lot of solutions before the start of the contest. Now during this time if there is a queue, they can decide whether to hold the contest or not. I mean this would at-least ensure that the efforts of the problem setters do not go to waste.
Where is editorial? I am waiting for it.
has codeforces round 640 just been cancelled?
I think it will be delayed a little bit.
I've just noticed that 'CF round 640' has been removed from the list. What's the plan? We all want to have a rated round shortly :|
Update: CF round 640 has been added as Div-4 !!! Quite surprising!
https://codeforces.me/blog/entry/77028
It would be interesting
Please release tutorials lol
does anyone has the solution for the C problem ? i tried to solve but my solution seem not to be right!
Right after reading C, I came up with your solution too. It is actually pair<pair, pair> not only pair. Instead of just using set<pair<int,int>>, u may need to use set<pair<pair,pair>>
i've seen your code ! but i confuseed and dont understand why we would use that pair<pair, pair> :<
We need to store pair of pairs because we need to store the paths visited instead of just points. Why? Take a testcase WNES. Storing only points will result into answer 16 as you have already visited point (0,0). This is wrong. The correct answer is 20. The path is (0,0)->(1,0)->(1,1)->(0,1)->(0,0). You can see that all the paths are visited only once and hence the answer is 20. Hope it helps!
ohh , i got it thanks so much
where is the editorial?
I wrote one unofficial