Codeforces Beta Round #8

15 лет назад, # ^ |

If it's tough for you, find more easy challenge then.

Do you know any contests with test cases release?

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15 лет назад, # ^ |

Yes. TopCoder.

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15 лет назад, # ^ |

Hm, yeah, I didn't think about TopCoder. Sorry then.

But anyway, there's more sense to proceed solve problems in practice room without knowledge of the test cases, in my opinion.

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eduardische

15 лет назад, # ^ |

Hm... Let me think... Like IOI, TopCoder, COCI, USACO and pretty much everything IOI-style...

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15 лет назад, # ^ |

OK, I agree.

But this competition is in ACPC style and in this way organizers hide test cases even after the end of the competition.

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eduardische

15 лет назад, # ^ |

Well, in ICPC you also can't view other person code, I guess. But here, you can download Petr's solution and just randomize cases until you find a non-working case on your code (I tihnk, that's gonna happen not so rarely). So, it will just make possible task simplier to release test cases after the contest.

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vdmedragon

15 лет назад, # ^ |

Hi, where I can download Petr's solutions?

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eduardische

15 лет назад, # ^ |

Enter contest -> Click on a number, showing how many users solved this task -> Click on any submission number

It seems, that you can't scroll through all submissions, but you will find some "Accepted" for sure.

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_arjun

15 лет назад, # ^ |

i thnk now no one (except admin) can get "petr"'s solution(i have checked each sort option)

showing solution in this way is not quiet uncomfortable to access...

it shud be accesible through STANDING page.....

so that everyone can see the solution of high rankers comfortably...(well that another kind of sort i think....... :) )

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slycelote

15 лет назад, # ^ |

Actually you can view Petr's solutions, check this out:
http://codeforces.net/contest/8/status/B?order=BY_ARRIVED_ASC

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_arjun

15 лет назад, # ^ |

sorry I forgot mentioning....

actually i was searching for problem A...... :)

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slycelote

15 лет назад, # ^ |

http://codeforces.net/contest/8/status/A?order=BY_ARRIVED_ASC
You can view any problem, just append order=BY_ARRIVED_ASC manually to the URL.

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nvilcins

15 лет назад, # ^ |

I am a fan of constructive argumentation; I would, therefore, be happy to learn some advantages of not releasing official test data. Until that I support all the frustrated coders who just can't find bugs in their solutions. Contest is one thing, but in my opinion the process of practice would only benefit if test data was available - whether one decides to use it or not, it is totally his/her responsibility and choice of training techniques.

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15 лет назад, # ^ |

You can view accepted solutions and compare them with your one. It's useful excercise.

What does Mikhail Mirzayanov think about test data release?

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15 лет назад, # ^ |

I think that open test would be useful.

Especially when an error is in technical details e.g. array sizes etc.

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ick2	15 лет назад, # \| +1 why can the problem C shows out the PE error? → Ответить

pablo.aguilar

15 лет назад, # ^ |

Same problem here. Any ideas on why the PE for problem C test 5?

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Fefer_Ivan

15 лет назад, # ^ |

It is not differ much from WA.

Solution returned some time T, and some order P.

PE returned when total time, needed to collect objects in order P differ from time T.

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Enric

15 лет назад, # ^ |

It also happened to me. It was path reconstruction.

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pablo.aguilar

15 лет назад, # ^ |

Thanks Fefer and Enric, got AC now.

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15 лет назад, # ^ |

hi~can you tell me how did you solved the PE problem on test 5?

i've been stuck at it for more than 2 hours...and can't find my problem...

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pablo.aguilar

15 лет назад, # ^ |

In my case, it was that my program first attempted to pick up a pair of objects, and recorded the best option, and afterwards when it tried picking up only one and found a better solution, it forgot to say "only pick up one" and so the order it output was wrong.

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Olexiy

15 лет назад, # |

Really liked the problems, but 1 geometry would be really enough :)

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ick2	15 лет назад, # \| 0 i think this time,the judge is too terrible:( → Ответить

unrated

15 лет назад, # |

Может быть было бы лучше если бы для участников 1 дивизиона был отдельный рейтинг, для 2 див. отдельно. А рейтинг можно оставить.

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15 лет назад, # ^ |

+12

Codeforces Beta Round #7:

С сегодняшнего контеста рейтинг по дивизионам для общих контестов будет считаться отдельно по двум таблицам положений участников. То есть подсчет рейтинга будет эквивалентен проведению двух контестов отдельно для каждого дивизиона по общим задачам.

Ты про это спрашивал?

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luckman

15 лет назад, # ^ |

А так вот оно что.

А то я уже заметил некоторую странность в подсчете рейтинга.

Просто если так считать, то получилось что некоторые люди из второго дивизиона меня обогнали, хотя место в раунде у них было ниже и до соревнования их рейтинг был ниже, то есть по идее они обгонять не должны никак.

А на стыке двух дивизионов получается такая вещь.

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15 лет назад, # ^ |

Just like in the TopCoder.

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luckman

15 лет назад, # ^ |

Но на топкодере то хотя бы контесты разные проводят, а то когда один контест и один монитор получается по-моему странно.

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15 лет назад, # ^ |

You can watch the Monitor for only selected div. All is gonna be Ok after that. =)

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unrated

15 лет назад, # ^ |

Спасибо..... Я не знал

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Kenny_HORROR

15 лет назад, # |

It's a pity that testing problem isn't fully solved... Especially it felt at the end of the round, where appeared a huge queue of problems to test.

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15 лет назад, # |

Petr is Red now.

The Red is the color of other contestants' blood. =) =)

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skywalker

15 лет назад, # |

Could you please post the 9-th test for the B problem? :)

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smilitude

15 лет назад, # ^ |

I think the 9th case consist of something like this,
UURRDL

Here the answer should be "BUG", but if you don't check the adjacent squares, you'd get "OK".

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Anurag

15 лет назад, # |

please provide the #Test9 for A - Train and Peter

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15 лет назад, # ^ |

Try that tests

aaacaa

aca

backward

aacaaa

aca

forward

aacaa

aca

fantasy

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dennismv

15 лет назад, # ^ |

how about ... UURD ?

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15 лет назад, # ^ |

It's for problem B.

And the ans is BUG.

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15 лет назад, # ^ |

Yes，it is a bug。

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15 лет назад, # |

I think its better check out a fine solution and find your own mistake.

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ick2	15 лет назад, # \| +1 how can i turn the pages in the status? → Ответить

15 лет назад, # ^ |

It seems that it's "under construction".

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rem	15 лет назад, # \| 0 По-моему рейтинги обновились ещё до того, как закончилось тестирование всех решений. Это нормально? → Ответить

15 лет назад, # ^ |

Может всех решений, отправленных с контеста? (до 21:45)

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MikeMirzayanov

15 лет назад, # ^ |

Неправда ваша. Как только дотестировались контестные сабмиты - сразу рейтинг и обновили.

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15 лет назад, # |

Who wants to see a Petr in a train? =)

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15 лет назад, # ^ |

I want。

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Dasha

15 лет назад, # |

There are some odd effects with ratings. For example, before contest I was in Division 2, solved 2 problems and now I have rating 1603. MRoizner was in Division 1, solved 3 problems and now has rating 1567. It seems a little bit strange. =)

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15 лет назад, # ^ |

It's all right. He solved problems worse than average participant of his 1st div.

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15 лет назад, # ^ |

What's the different between Div 1 and Div 2?
I am a new for Codeforces.

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15 лет назад, # ^ |

Non-rated users (newbies) or those having less than 1500 rating points belongs to second division. Others ( >= 1500 rating ) belongs to first division.

By the way at first contest you have rating 1500 and have changes with it participating in second division.

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Petr	15 лет назад, # \| +20 Thanks for the nice problems! Although when I submitted D for the second time, I was almost completely sure it will fail again, since there're too many if's :) → Ответить

15 лет назад, # |

Hi. Is it possible to have a public Google Calendar with the match times updated on it? This saves me trouble of converting between Moscow and New York time all the time ;)

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15 лет назад, # ^ |

I have such calendar.

clndr

Is is suitable for you?

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15 лет назад, # ^ |

This works, but will it be updated at all times permanently? (i.e., whoever is maintaining that Calendar may get busy in life and stop updating.)

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15 лет назад, # ^ |

While the calendar will be updated he will be updated.

That's nothing more I can say about it.

By the way you can tell me if I forgot something. That really helps sometimes.

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15 лет назад, # ^ |

Well, for one thing, TopCoder SRM 467 is marked on the wrong date, as far as I can tell.

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http://www.timeanddate.com/worldclock/fixedtime.html?&day=15&month=04&year=2010&hour=21&min=00&sec=0&p1=179

15 лет назад, # ^ |

+12

Why?

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15 лет назад, # ^ |

Am I wrong?

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15 лет назад, # ^ |

I am not sure. It shows up on my Calendar on Wednesday, but it is on Thursday. My time zone is synchronized with TopCoder so I am fairly confident.

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15 лет назад, # ^ |

Oh, realy my mistake. Thanks!

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http://acm.nankai.edu.cn/recent_contests.php

15 лет назад, # ^ |

really cool...

would you please tell me how you did it? I mean how to sync the information from the website to google calendar? because I want to arrange some contests from schools in my region, and they always post the time on their website, like this:

Thank you very much :D

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15 лет назад, # ^ |

I created a new calendar and pasted a contest event with time in my time zone. So I sync information by hands.

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itomatik

15 лет назад, # |

А уже были предложения сделать графики рейтинга для каждого участника? И кто-нить предлагал делать статистику по странам? :)

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15 лет назад, # ^ |

I think it will be implemented in future. =)

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15 лет назад, # |

still WA on problem B...

I've considered situations like UURD...

and I used a BFS.

But always get WA on the 1st Test....

any help?

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15 лет назад, # ^ |

You can use hash……I AC it with a map[230][230].

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snake

15 лет назад, # ^ |

no cycle,and bfs

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http://codeforces.net/blog/entry/259#comment-2894

15 лет назад, # ^ |

+12

galymzhan:

Problem B doesn't need BFS. I solved it in linear time using followin approach:
set all f[201][201] = 0;
set f[100][100] = 1; // start location
simulate moving and for each new location f[x][y], check the sum of four adjacent cells. If the sum > 1 then answer is BUG.

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15 лет назад, # ^ |

UP
me too.I solve it without bfs.

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15 лет назад, # ^ |

nice algorithm

But my method should not be wrong =.=

still can't find my error...

Maybe I should wait till test cases are released. :(

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15 лет назад, # ^ |

Does the test UD gets a BUG?

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15 лет назад, # ^ |

yep...I tried this.

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OmarEl-Mohandes

15 лет назад, # ^ |

Hey, I solved mine like your idea exactly and the same problem ...but i think there is something wrong in the judge.have a look in my BFS function and got AC when i add that line , have a look:

#include <iostream>

#include <queue>

#include <memory.h>

using namespace std;

#define pb push_back

#define rep(i,m) for(int i=0;i<m;i++)

#define mem(a,b) memset(a,b,sizeof(a))

#define mp make_pair

typedef vector<int> vi;

typedef vector<vector<int> > vii;

typedef long long ll;

#define oo ((int)1e9)

int arr[1001][1001];

int vis[1001][1001];

int dx[]={0 , 1 , 0 , -1};

int dy[]={1 , 0 , -1 , 0};

int BFS(int ii , int jj){

queue<pair<int , pair<int , int> > > q;

q.push(make_pair(0 , make_pair(500 , 500)));

vis[500][500] = 1;

while(!q.empty()){

int j = q.front().second.first , k = q.front().second.second , len = q.front().first;

q.pop();

if(ii == j && k == jj)return len;

rep(i , 4)

{

if(arr[dx[i]+j][dy[i]+k] == 0 || vis[dx[i]+j][dy[i]+k])continue;

q.push(make_pair(len+1 , make_pair(dx[i]+j, dy[i]+k)));

vis[dx[i]+j][dy[i]+k] = 1;

}

cout << "It will never cout this !!" ;

return 0; // without this line it will get WA in test case 1 , Now AC

}

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15 лет назад, # ^ |

thx a lot...but that's not my problem .

I will try to rewrite this problem again...maybe there are some small flaws in my program, though I tried thousands times to make sure it won't :D

BTW: It's not the problem about the judge.

the line: "return 0; "

gives the operation a signal that the program ends correctly.

otherwise the operating system on the server would think this program has some wrong, because no signal inform it that the program is right.

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OmarEl-Mohandes

15 лет назад, # ^ |

The return 0 is not in the main, its in a function I call. Also control never reaches this statement (Thats why I added a cout before it to double check).

It compiles successfully at the judge? Why should not work?

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