Looking forward to it! Such a long time since the last Div 1 round.

You are a programmer AND you have a girlfriend!!!

you are my role model dude.

"And I want to thank my girlfriend because there would be no Limak without her." congratulations on becoming a father!

You are my favourite problem setter! Too bad I will miss this round.

Looking forward to "Bear and Forgotten Tree Girlfriend"! :)

Anyway, this contest will surely be great as always. Thank you Errichto!

Yes! The stories with Limak are always nice to read :)

Errichto be like, Petr's getting closer to me on the contribution list, lemme prepare a new round and make his mission impossible lol .
You always come with great problems, eagerly waiting for the round and hope I'll be able to participate, thank you .

I'm looking forward to it. You wrote some very nice problems in the past. I hope there will be many algorithmic problems :D

Limak has a great subliminal message. Reverse it first: Kamil. It is the name of first Turkish polarbear manufacturer.

my 1st div1 participation , am I gonna go back to div2 ?? I hope not :p

Errichto, Your Problem Statements are So clear to me. I Solved Your problems in Hackerrank too. Thanks You.

Good Luck & Have Fun!

We get it, you have a girlfriend.

Tbh, Limak scares me. The later problems turn out to be DPs, which are scary for me. The quality of questions are great, though.

That's GOOD

Guess there will be statement like that:

As Limak is a bear and he can't solve the problem by himself, so he ask you for help. Can you help him?

This may be strange, but I'm becoming a fan of Errichto, his posts, comments and problems. :)

Wish me good luck guys I really feel like I'm gonna make it!!

I'm wondering if this little polar bear is preparing a problem about powers of prime numbers ? :p

i really hope that the pretests would be strong enough , because it's sucks when you spend a lot of time working on Problems and gets the same position of someone spent all the time refresh room page to hacks someone else solutions.

Hope I can get my first 4/5 at your round, after 4 unsuccessful try -_-

What do you mean by "your first standard round" — were the others prepared by you a non standard?

It's fun that the last CF Round I took part in is on the Chinese Spring Festival, and this one is on the Dragon Boat Festival.

Thumbs up for those playing cards from World Finals 2012! :)

It's recommended to read the Interactive Problems Guide prepared by Mike Mirzayanov.

i think the second problem will be interactive as second card is hidden in the image .

So it is not a standart round as well :p

Having interactive problems adds to fun of Competitive Programming. :)

It's about time I left the green phase without a second comeback

Good luck everyone

Oh, div2 C scores 1750, I have a bad feeling..

Feels like experimental round, poor you Errichto

Bad feelings :(

I had great fun solving Div2/C. Thanks for the nice problems, Errichto!

My solution to problem C.Whenever i tried to submit it , my browser get stuck on the same page. More interesting part is that submitting this solution to any other problem results the same.

Why am I getting WA for Div2 C?

int sieve[1000];

set st;

bool isPrime(int num) {

return (st.find(num) != st.end()); 

}

int main() {

//t(); 

st= { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 }; 


vi v; 

for (int i = 2; i <= 10; i++) {

    cout << i << endl;

    fflush(stdout);

    string s;
    cin >> s; 

    if (s == "yes") v.pb(i); 

}

if (v.size() == 0) { cout << "prime" << endl; fflush(stdout); return 0;  }

if (v.size() ==  1) {

    if (!isPrime(v[0])) { cout << "composite" << endl; fflush(stdout); return 0; }

    else {

       cout << v[0] * v[0] << endl;
       fflush(stdout);
       string s; 
       cin >> s; 

       if (s == "yes") { cout << "composite" << endl; fflush(stdout); return  0; }

       else { cout << "prime" << endl; fflush(stdout); return 0;  }

    }


}


if (v.size() > 1) { cout << "composite" << endl; fflush(stdout); return 0; }



return  0;  

}

i got stuck on C because i didn't take perfect squares in account

How to solve Div 2 — D?

According to me , the 3rd problem should be able to differentiate between coders and the number of people who solve should be <=700,800. That was definitely not the case today.

2 of my submissions were submitted at the exact same second . Can one of these be removed while considering penalty >.<

Problem Div2 C was really easy for hacks, because it had week pretests! For example, I hacked two people using "94" as a hack because they didn't check for 47. Another hack was "49", so no perfect squares.

TNX for your perfect contest and fast editorial guys.

After try spending 1 hour and 45 minutes on Div1-B:

I'll need to train harder next time...

Errichto when can we expect system testing? In 5 minutes or in a hour?

А все потому что закончились шишки и приходится курить табак((((( никогда не курите ребята!! никотин вреден для мозга я тому пример седня!!!(((

I want to know why my solution got run time error for div2 b. can anyone pls take a look? link to submission Thanks

I completely forgot to input m as a long long for problem D.

At least my solution probably had a bug somewhere else!

Again, A massive gap between Div.2 C and Div.2 D ...

Вобще блин так растроился(((( Теперь рейтинг точно упадет(((( Нада к Майклу в сазанку ехать он стопудово надрочит меня задачки щелкать на раздва(((

Ребята поддержите меня пожалуста мне грусно!!(((((((

I managed to find number of cubes in D and minimal volume. Was it the right way or this information is useless?

Forgot «47» in C... short div[] = {2, 3, 4, 5, 7, 9, 11, 13, 17, 19, 23, 25, 29, 31, 37, 41, 43, 47, 49} Frustraiting...

Can anyone please explain how to obtain the 0.916666666667 in the 3rd sample test of problem D?

hacked two solutions in div2 C and then realized that i was screwed ! 25 and 49 will hunt me down tonight . :(

Now-a-days contests have become extremely rare. And then to provide a contests like today is so disappointing...To do so much upsolving preparing for contests..for what? An interactive problem that almost 70% of the candidates can solve? Noooo...This is just not done..

Thank you for a wonderful round!)

Thank you very much, Errichto! I loved the problems!

I came up with the efficient approach for C right after the contest ended and it took me some 10-15 minutes more to code it, but I enjoyed the contest nevertheless :D

my eyes almost got cancer from debugging this.. only realizing my l and j is swapped after the contest is finish..

The waiting for rating change has just begun.

Thank you for participation and for kind words. Also thanks for bad words (as long as it's something constructive/reasonable). Btw. div2 participants can now check again a picture from the blog. Do you know why is there one card hidden?

Awesome contest!!! :D Solved 3. Coded brute force dp for 4th one but failed to find a tiny bug in time which was resulting in wrong answers for the tescases :/

My view of the points system this round 500 — 750 — 1250 — 2500 — 3500

Honestly, I miss the dynamic scoring.