Hello, Codeforces!
My name is Adilet Zhaxybay, and together with Bekzhan Kassenov (BekzhanKassenov) we are authors of Codeforces #294, which will be held on 28th of February at 16:00 MSK. This is our first Codeforces round and we are happy to invite all of you to participate in it. The round will be rated for the second division, however, participants from the first division can, as usually, participate in it unofficially.
As far as we know, it is the first Codeforces round, which was completely prepared by the authors from Kazakhstan. We are very honored by this fact and hope that everything will go great. We are encouraging other participants from our country to join us — I am sure, that you can prepare a lot of very nice problems. Preparing Codeforces round is possible ;)
We want to thank all the people, who helped us to prepare the contest: Max Akhmedov (Zlobober), who helped us with the problems, Nurlan Kanapin (kt-9) and Mansur Kutybaev (mexmans), who tested the round, and Maria Belova (Delinur), who translated problem statements.
Also we want to say great thanks to Mike Mirzayanov (MikeMirzayanov) for creating Codeforces and Polygon. We want to congratulate Codeforces with its fifth anniversary. We, authors of the round, were very lucky to start competitive programming at the time, when Codeforces already existed, and it helped us really a lot!
We love, when authors of the round write a bit about themselves (we encourage everybody to do so) — this helps to feel that there are real people behind the problems. Thus, we will write a bit about ourselves. We are students from Nazarbayev University (nu.edu.kz). NU is a new university with English as a language of teaching, which is located in the capital of Kazakhstan, Astana. Our university participates in ACM-ICPC only from 2012, but the team from NU already qualified to World Finals twice — in 2014 and 2015. We hope that we will do only better in the future!
Good luck to all!
UPD Score distribution will be standard (500 — 1000 — 1500 — 2000 — 2500)
UPD2 Editorial is available here
Congratulations to winners!
Round is over, thanks to everybody, who took part in it!
Hope for finally become blue :)
Do not hope
You never gone blue
you become purple
My hope has been granted :)
Congrats! Mine too. :)
If you want, you can!
Congrats for being first in country to prepare a codeforces round. Hoping your efforts will inspire many people in your country.
For the sake of fairness: azizkhan was one of the authors of Codeforces Round #202. We are just first, who prepared complete round.
Wahhey, first complete round from my country!
Always dreamed to write this comment (
afarin be country shoma
This contest overlaps with Challenge24 :(
you boro challenge24 bede we haminja contest midim
Can you shut up please?!
no I can't (:
I am really sorry bekzhan29)
Why isn't this page on the frontpage? Isn't this an official contest?
It's an official contest. Just appeared on the front page.
hope we enjoy the problems
we too (:
Attention guys, it's an individual contest.
In this world, winning is everything; winners are validated and losers are denied. Until now, I've never lost at anything, and I won't in the future. Since I always win, I'm always right. If you oppose me... I'll kill you, no matter who you are.
miay teeworlds?
Ya, we know that by looking at the time you created your account at.
teach me how to spout nonsense without getting embarrassed please because the things you just said made laughing a medicine for me =))
I'm pretty sure everyone is so much concerned with their lives and won't dare to oppose you. But I was just wondering what if the Online Judge oppose you and give you a verdict other than Accepted!
That cant happen because i am always right, i make no mistakes
I think he is just acting like the character Akashi Seijuro... Those words were all originally from the anime....
i am not acting, i am Akashi. winning is everything and i never lose as you can see in standings
Next round you will be introduced with div 1 coders.
just look tourist and shut up :|
look for help bro :)
@Akashi: Sorry but you will loose both in the anime and in div1 soon :)
I am ze ghamat very very sorry pictureato bede for yadegari
pls dis like me for kossher haye bala
chi kos migi ?
taghriban
kos shero put karde too koonesh dg
please speak English ! and don't be rude :|
Stop fighting :|
I wanted to take a walk today. Maybe I will do it tomorrow. Priority has codeforces :P
Usually I ignore large post, blog and announcement. But this one is so much encouraging that I can't ignore. May be one day I will be an author like you :). Best wishes to you guys.
I thought contest would be delayed for 10 min, but registrants 4965!
I missed the contest :-(. I thought it was at 16:00 local time.
I think problems were easier than standard for a Div. 2 contest IMHO.
Yes... of course that was first contest of ADJA we hope next contest be better :-"
I'm wondering... What's the test case for problem A that got all these hacks?
People thought knight was K lololol
made that mistake ;)
I use something like this: ....K... ........ ........ ........ ........ ........ ........ ........ (the code will fail this test case if they add 1 for 'K' or 'k')
Also some people / not in my room :( / use 9 instead of 8 for Q.
Wait... Aren't you supposed to use 9 for Q?
Yes... Changing 8 by 9 I mean...
how to solve E??
I missed the contest but I guess it's related to LCA.
Preprocessing: LCA preprocessing and making an array of heights of nodes (h[]), quantities of nodes in the subtrees (sub[]), ancestors of levels 1,2,4,8,16... If we have ancestors of these levels, we can find ancestor of any level with O(log(N)) time.
Solution: if a==b, the answer is n. Else find LCA(a,b)=c. If heights of a and b are the same, the middle is c. We can find ancestors of a and b that are childs of c (call them e and f), because we know that they are a and b ancestors of the (h[a]-h[c]-1)th level (complexity O(log(N))). Then the answer is n-sub[e]-sub[f]. If heights of a and b are not the same, then either h[a]-h[b] is odd — then answer is 0, or is even — then we know where the middle node e is situated. If its child closer to a or b is f, the answer is sub[e]-sub[f].
thanks got it ....
WA on test 20 ¿?
I solved it that way but I keep getting TLE on 7th test case. My solution--> http://codeforces.net/contest/519/submission/10136461
Sorry my fault, my code was right but I thought roads in input were correct (i.e. a is closer to the root than b) so it was going on infinite loop. lol
Also prima[][] is unnecessary here. http://codeforces.net/contest/519/submission/10138678
C looks easier, than A for me.
I finally find my blade.
.
.
.
If you know what I mean :-troll.
How do I do E? I know its a tree.
How to do C problem.I solved it recursively but dont know how to optimize it for large test case .Thanx
my solution is to print the minimum of (n+m)/3 and n and m
Greedily, whichever out of n or m is larger subtract 2 from it and subtract 1 from the other until one of them is smaller than 2 and the other smaller than 1.
Easiest solution i found was:
Ans=(a+b)/3
Ans=min(Ans,min(a,b))
I doubt this tho
ans=min(n,m,(n+m)/3) :)
i did something like this 1+max(solve(n-1,m-2),solve(n-2,m-1));where solve is my function.
Did it work? Looks like exponential time to me. Or n^2 if memorized.
Can anyone tell me how to solve D? I can't wait till Editorial
Who can say 5 pretest of C?
How is D solved?
i did this:
keep this : array[ each partial sum amount ][ each character ] = number of occurences of that character with the amount of partial sum.
(by partial sum i mean sum of all values from the first to the i'th character) since the amount of partial sum can be large and also negative you need map ( or unordered_map )
when you want to add a new partial sum you must see how many of the previous partial sum and the current character had occured and add this amount to the ans.
what's the meaning of "Validator 'validator.exe' returns exit code 3 [FAIL Expected EOLN (stdin)]" when hack others' code?
my submitted code is http://codeforces.net/contest/519/hacks/140490/test
After looking, it might be because of the extra space you print at the end of each line... I'm not sure but I know that the validator is very strict.
It's kind of you to answer my question~
you need to print "\n" at the end of your input.
shold i use printf("\n") replace "puts("")" ?
No, I said that before I saw your code... I think puts("") is fine.
You have a trailing space at the end of the lines
Use
%d%c ... i == n - 1 ? '\n' : ' '
I think for prob C it will be more challenging if the input range is bigger, something like 0 <= n, m <= 5.10^9. with 10^5, even brute force implementation can pass. But, overall, nice contest!
min(n,m,(n+m)/3) is not very challenging even 10^18. if this solution is correct...
I know, but at least brute force implementation will not pass (and maybe can gives more hacks.)
let's wait system testing, and look at solutions 1500 score problem.)))
This is so unfair. They skipped my solution to problem C. It was a super simple 10 line solution. How can it be skipped ? It may be due to coincidence that my solution is similar to someone else since it involved only 3 variables and simple commands!
Erm... About problem A...
Thanks for very fast system testing!
Let's hope for fast rating updates too :D
UPD. It was very fast :) Thank you!
I don't understand why my submission is not any giving output. For the same case my solution is giving output in my codeblocks.
I don't understand it either. I submitted your code without any modifications and got AC 10086878
Try to write admins about that.
Editorial is published here
There are a lot of people who unrated joined this contest. I think they are from DIV1... Not fair play
I don't have this efficiency in Div. 1 contests :( :-"
Please explain problem D?
Ok)) I am need too))
Speed contest
It's another swarm of unrated competitors...
Hello programmers! How I an quicly find general parent of two vertex on tree? For O(1) or O(logn) ?
LCA tutorial on topcoder.
thank you))
Thank you all who participated in the contest! We enjoyed it. Hope you too :)
I have written small blog post about what is like to be problemsetter: link. I will be happy, if this helps you to have a feeling of what is going on behind the scenes.
See you in the next contests ;)
Top 8 participants are unranked... Are you shi'in me?
Seems like AkashiSeijuro used his Emperor's eye this time...
Nice!!! I became purple :P But I'm banging my head: stupid mistake on problem D, not using long long catch me again :(
say goodbye to int try typedef long long ll; and use ll everytime !
How this submission passed system tests?
Sum of all numbers in first array must be maximum 1e5 * 1e9 = 1e14
1e14 > 2^31-1
It's the same as performing all operations modulo 2^32
How about this case:
that code gives wrong answer. The variables needed to be long long.
It gives Correct Answer!
http://codeforces.net/contest/519/submission/10066478
Hi Java fans. Don't forget that it's not right to compare Integers by ==. Use equals instead:)
http://codeforces.net/contest/519/submission/10085682
When I submitted my code, the verdict was AC. But when I open my submission page, the verdict has been WA.
my source code is here -> http://codeforces.net/contest/519/submission/10067289
Everything has changed after a few hours. What's the matter with test 6 ?
When you submit a solution during the contest, it's checked only on a small number of cases (pretests). Only after the contest ended, it's run on a larger number of cases (system tests). Your solution is incorrect because it considers only 4 rows of the chessboard. It passed pretests but failed system tests.
thanks for your help =))
Is there a tutorial for this contest? I can't find it. Somebody provides me with the link, please.
http://codeforces.net/blog/entry/16687
all unrated guys have won,, u konw what i mean
Did you have a seizure when you were writing the second half?
English Editorial please.
Need editorial to 5th ques.
just replace the ru in the url with com http://codeforces.net/blog/entry/16687
Thanks for this round. Finally become purple after 15 contests. :)
Really thank this round, I finally became blue!
But I lost 91 points!
Could not solve problem C just for missing the line "Furthermore, they agree that the total number of teams should be as much as possible." :( :(
I mean that is a pretty crucial line, it states the goal of the problem. If after reading a statement you do not know the goal of the problem you should reread statement. Overall I thought it was a very clear description of the problem.