An unusual round with tricky problem. Programmers be like "Brace yourself, storm is coming!"

Вау, даже разбалловка быстро обьявлена

i wonder which question is going to be tricky :D

А для саратовских школьников этот раунд будет в качестве школьного этапа? Или они уже писали/будут писать?

Эх, не очень удобно будет с пары писать...

Tfw CF rounds are getting earlier and earlier, from starting at mid-night (00:35) to starting at supper's time (19:35).

Good luck for everyone that's joining.

hope the translation is good enough to understand clearly, unlike last round.

What is the reason behind setting contest time so early?

you only needed one more problem to make contest for both divisions. poor div.1

EDIT : It seems downvotes are coming :(

When A Problem is tricky

game time is good for china

Раунд специально для тех школьников, у которых сегодня диспансеризация?)))

salam

what does tricky means?

"Tricky problems" --> Hacks contest xD

Finally CodeForces loaded for me :( But alas around 40 minutes are gone :(

I cant even understand the problem statement for C!

Я думал что раунд должен был начаться в 16:35 по МСК. Специально торопился домой. А тут сморю "соревнование идет 00:40". Разочарование (((

What is the problem for D? I keep getting WA on test 7.

Only a few numbers of hack wow!!!

Poor English #C..

Problem statement for C was too difficult to understand

It was an AMAZING AND WONDERFUL contest! Problems were really interesting and pretests were strong enough.

Thank you fcspartakm

EDIT : according to zscoder pretests were strong enough for A to D!

I see someone has used -1 index to access array. And he passed the test. Is it possible?

.

how to solve C?

Once again, very nice problemset! I really enjoyed the contest, although I couldn't do D — my approach was with DSU, however there's some tiny mistake in my code that I didn't find...

When you submit in the last couple seconds of the contest only to get WA because you put "YES" rather than "Yes"... sad times.

Is div2E a flow-related question? The small (n,m) constraints looks suspicious to me.

pls help me with D

I got into many dfs but failed...

http://mirror.codeforces.com/contest/723/submission/21154778

misread D as transforming land to water to reduce the lake number, and struggleed for 90 min to write a complicated solution and found I was so stupid...

quick editorial .

Maybe my English is too poor. Can't understand problem C at all.

Will system test start right away? Or With some delay? Thanks in advance

The quick editorial makes this contest best ever

It's the second time that I come up with a solution to a problem several minutes after contest ends... sad :(

in problem D: "and it's impossible to add one more water cell to the set such that it will be connected with any other cell"

Before clarification, I overthink that statement and after complicated process implying that the river can't have hole, can't fork, and can't turn, LOL. Thanks for fast clarification btw, save me much time :)

It took lot of time to understand problem statement for C. Because of this I could not implement problem D :(
The contest has nice set of questions. Hope to see more rounds from fcspartakm
EDIT Now problem C fails System Test. I think I should have given time to problem D

Опоздал на 5 минут... Участвовал весь раунд параллельно устанавливая CodeBlocks, Dev-C++ и PascalABC на компьютеры...

Итог: за 5 минут до конца решил последнюю задачу.

Вывод: даже если занят работой — решай задачи.

UPD: Правда С упала...

UPD2: И E...

It costs me much time to understand the mean of the Announcement,and i just realized that it is no use to me after passing the PTs...I think the most difficult part for me to solve the problem C is the EN. (:P)

I know that it isnt related to this contest, but I am wondering my rating is 1318 pupil even though i got specialist at my first game i am 14 years old and i honestly wonder if i am doing good of i should improve my skills to meet standards?

Problems are very interesting, hope more rounds from fcspartakm!

Is anyone read statement of D and think statement require replace land by water instead of replace water by land like me ?? f*** my very bad E !! PS : Can anyone solve problem D like my mistakes =))

How to prove greedy works for E?

Randomly taking edge and orienting all edges to satisfy nodes with even degree gets AC. How to prove this is correct? Also, if this is indeed correct why is constraint on N so low? I got misled into thinking solution is something via MCMF. Example: 21156793

Pls help me, problem D

I got WA on test 7:

http://mirror.codeforces.com/contest/723/submission/21158564

IS all python solution for D get RTE because of recursion depth limit reach ?

Very hard to understand problem C. I wasted about 30 mins after it. Then let it go, solved D. Now I regret why I did not read problem D without wasting time after problem C. -__-

Why aren't editorials written before the contest and published as it ends?

I just changed an array's size from 1000 to 2000 in problem D and got AC after the contest :((

Nice problemset ... Specially C & E ... overall Nice contest waiting for rating change !!!!

Больше ДФСа! Прямо как я люблю.

the idea of the most tricky problem which one was the tricky one ?

i'm so hungry when i programed

The pretests for F may be too weak. With a wrong character in my program, it got pretest passed and pass 47 tests. So to me, it's a little bit surprising to see so few hacks on F after finding such a silly mistake in a pp program.

I found problem C's writing quite poor.

What was the purpose of writing "Polycarp likes bands with the numbers from 1 to m, but he doesn't really like others."? Was it to confuse people???? Why, if Polycarp does not like numbers greater than m, are there playlists with such numbers (test case 7)?

This is totally ambiguous and this should have been made explicit.

Когда-нибудь я перестану считать без калькулятора... или пользоваться статическими массивами...

200 * 200 != 4000 И это грустно... Добавил нолик и E — AC...

My solution for C got one line in wrong ordered which should give wrong answer to many of the tests but somehow passed the pretest then system test got me. :( Now I cannot tell whether I'm extremely unlucky or extremely lucky. Xp

//wrong one which pass the pretest
a[i]=*needer.rbegin();
needer.pop_back();
give[a[i]]--;
//right one that i figured out after the contest
give[a[i]]--;
a[i]=*needer.rbegin();
needer.pop_back();

FEELSBADMAN

My fortune is that I didn't read D statement. It was clear from input/output and clar.

Объясните, почему такой вердикт на поссылке http://mirror.codeforces.com/contest/723/submission/21148825 ? Я пересдал, оказалась проблема в том что я использую вектор для ответа( когда поменял на на массив получил АС ( http://mirror.codeforces.com/contest/723/submission/21162757 ) ).

Problem C's statement is so silly and confusing i couldn't even understand it till the end of the contest .

This is a very, very, very exciting and thrilling round!

C is failed for...typo?(confirmed, "m" should be "per")

E is failed for missing a if statement in dfs process to judge the starting point of circle.

UPD: F is only one statement away to get Accepted (I missed a statement like "a--").

The rating, certainty, will drop. But I have got so much fun.

Horrible problem statement for C. Why are bands numbered more than m included in the play list if he doesn't like numbers > m?! I solved the question in 1h10m then got a test case for which my solution printed values greater than m.

so I tried to fix that for the rest of the contest without even trying D question.

Had the question been clear I could've used the remaining time to try D. Just pathetic problem statements.

547D has the same idea with problem E.(But 547D have very different statement.) Everybody can try it. XD

That's an extremely exciting party!

Why my first submit also been skipped.?

I met a very strange problem, it cost me a lot of time and badly affect my standing. I still cannot figure out what the problem is. It's problem B. I ran it correctly locally but it could not even pass pretest 1. And When I debug it on code forces, it became very weird.

#include <iostream>
#include <vector>
#include <string.h>

using namespace std;

#define pb push_back
#define mp make_pair
#define ll long long
#define ull unsigned ll
#define db double
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define PII pair<int, int>

vector<string> inp;
vector<string> outp;
int main() {
    int len;
    string str;
    cin >> len >> str;
    str += "_";
    bool flag = true;
    char buf[512];
    int idx = -1;
    for (int i = 0; i < str.size(); i++) {
        char c = str[i];
        if (c == '(') {
            if (idx >= 0) {
                outp.pb(string(buf));
                memset(buf, 0, sizeof(buf));
                idx = -1;
            }
            flag = false;
        } else if (c == ')') {
            if (idx >= 0) {
                inp.pb(string(buf));
                memset(buf, 0, sizeof(buf));
                idx = -1;
            }
            flag = true;
        } else if (c == '_') {
            if (idx >= 0) {
                if (flag) outp.pb(string(buf));
                else inp.pb(string(buf));
                memset(buf, 0, sizeof(buf));
            }
            idx = -1;
        } else {
            buf[++idx] = c;
        }
    }
    int a = 0;
    for (int i = 0; i < outp.size(); i++) {
        a = max(a, (int)outp[i].size());
        //cout << a << endl;
    }
    cout << a << " " << inp.size() << endl;

}

This is is my code for problem B. You can see the line I commented. If I uncomments it, it outputs correct number for pretest1. However, when I comment it, it outputs 13 or 7 sometimes randomly.

Please take a look at these submissions: my submission1 my submission2 my submission3

Is this a bug? Again, when my code runs locally, it outputs correct answer. Hope someone could help me. What's wrong? It drives me crazy!

I first misunderstood problem D and thought that I'm allowed to change " * " sign to ".". I found this problem interesting but couldn't come up with any solution.

It's a perfect time,especially for the Chinese! It's the first time that there's even no hacks in my room!How tricky!

Hi! I tried to attempt 375D, and this is my solution: http://ideone.com/VtXhW5

I've tried really hard to debug it and gives strange outputs on ideone and something very different(and coloured) on another online IDE. Could someone please help me out?