Hello everyone!

As many of you already know, today is the day for Codeforces Round #127 missing which is really undesirable ;)

Original problems for you were created by tourist and Romka. We tried to emphasize the ideological component of the problems, thus we hope that you'll spend more time thinking than coding. Special thanks for helping in setting the contest go to Codeforces coordinator Gerald. We also thank Delinur for translating the problem statements and Alex_KPR for reviewing them.

We hope that this round won't be just a regular Codeforces round for you, but will bring you new experience and new knowledge. For the authors all problems are equally easy, yet we tried to arrange them in decreasing order of simplicity :)

Problems' point values in Division 1 are 1000-1000-1500-2000-2500. Problems' point values in Division 2 are 500-1000-2000-2000-2500.

Wish you success!

**UPD:** The contest is over, thanks all for participating. We hope you enjoyed it :)

In Division 1 rng_58 was a clear winner, solving all 5 problems in an hour and a half! No one else managed to solve all problems in two hours.

The winners in Division 1 are (full results):

In Division 2 every problem was solved by somebody, but nobody managed to solve all problems. The battle was very tough and the gaps were very small.

The winners in Division 2 are (full results):

Congratulations to the winners!

**UPD2:** The editorial is available now.

This will be my 1st participation ever on a codeforces round!! I am looking forward to it

good luck then ;-)

As points seem to be in increasing order, it suggests that also the difficulty of tasks is increasing rather than decreasing... am I right? :)

Yes, you're right: in Russian version it's written: "in decreasing order of simplicity".

Thanks man, always good to know where to start :)

Yes, I meant "in decreasing order of simplicity" :) Thanks, I've corrected it.

I'm learning Einglish！>_<"yet we tried to arrange them in decreasing order of difficulty :)"

decreasing order with points increasing?

That was a mistake, sorry. It should be "in decreasing order of simplicity", of course.

I really like the idea ;-)

"For the authors all problems are equally easy, yet we tried to arrange them in decreasing order of simplicity :)" Nevertheless, we recommend you to read all the statements and hope you won't get stuck on one problem losing possibility to solve other problems.

I Hope Short statements ,easy to understand and more thinking.

I like such problem statements too, like the one in SRM 547, Div I, easy.

Totally agree with you.

I feel it will be hot !!!

I was the author of this problem... http://community.topcoder.com/stat?c=problem_statement&pm=11133

So Ivan won't accept that problem for Torcoder? :)

I don't think the SRM's problem contains a permutation of the codeforces's problem as a subsequence :)

Turns out it wasn't a brand new problem [:|||:] :)

We're really sorry that this happened. We both missed that SRM, so there was hardly a chance for either of us to find that out.

I know it's impossible to completely avoid "duped" problem. I'm just a bit surprised.

What is the logic behind Div-2 Problem C ??

just try it out wid some input values and observe the pattern....look for dependencies if any cell is 1..u wil find cells dependent in groups of 4, 2 and 1..so each square of size n gives some 4 pairs, some 2 pair and 1 one. now all possible combinations of sums from these pairs can be reached with square of size n. max sum dat can be reached using square of size n is sum of all pairs of 4, 2 and 1.

by tring wid some i/p values i meant to say .try wid square size n=1,2,3..and find wat sums can be formed using these squares..

Why is the output of x=3 is 5 ..Cant we have something like:

it is not symetric.

Oh..I just read "Let's call matrix A symmetrical if it matches the matrices formed from it by a horizontal and/or a vertical reflection" and skipped the formal description.. From that statement I had made the conclusion that if we place a mirror on the bottom or the right and take the reflection and match then if we get the same array ,Its done..

y not..

0 1 0

0 1 0

0 1 0

for x=3...??

You have adjacent "1".

oh shittt....

jst got lost with that symmetric thng....

thnx.

for x=3..we have pair of 1 4's and 1 one. ..u need to understand symmetricity as mentioned in prob.. all corner cells should be same..either all 0 or all 1...so this is one group of 4..and center cell is one group of 1...thus we cannot form x=3 using square of size 3..

The Div1-E has been mentioned on Topcoder before (check SRM 484 Div1-Hard editorial) for reference). EDIT: Too slow

i wish i had solved problem C...i think it failed for case x=2..other than prob A and C, rest of prob i felt quite tough...

Like the problem set! e.g., for problem C, after analyzing a bit we can actually come up a very simple DP algorithm. Problem A (the easiest one) is too tricky to trap me for a long time...

Any one Can tell me the Connection between Problem E with NumberMagic? ( SRM 484 Div 1 1000 ? ..

In Div2-C, how does the square look like for x = 3 ?

It can be done in matrix of size 5, but no less.

00000

00000

10101

00000

00000

[Edit:Slow]

0 0 1 0 0

0 0 0 0 0

0 0 1 0 0

0 0 0 0 0

0 0 1 0 0

00100 00000 00100 00000 00100

Somebody can tell me the value of n for x = 2 in problem C (div 2) and how the matrix looks like? Thanks.

n = 3

0 0 0

1 0 1

0 0 0

n=3 010 000 010

I really dint want to do this.But I am facing a strange trouble in the submission of the problem-B of div 2. It gives wrong answer on pretest 11 but when I run the program in my system for the same input it is giving correct answer. Here is the link http://www.codeforces.com/contest/202/submission/1844228

Firstly u have given the wrong link.. The link is link

sry the correct link is http://www.codeforces.com/contest/202/submission/1844228

Excellent contest. It was not very suitable time for me but I don't regret that I tried to compete.

Output format in D was ridiculous (bad that non-Russian speakers won't get it).

Will it have an editoral?

FAIL:(

Minor mistakes (less than 5 chars of code each, one per task) in tasks B and C and I am 221th instead of ~90th.

I need to exercise more often.

Good contest anyway!

I have had a lot of fun!

## [:||||||||||:]

:-)4 a b c d 1 11 b c b a d d d a a c b for this test in B problem i am getting wa when in my pc i am getting the correct ans. code can anybody explain?

even iam having the same problem. If you get why it is happening please post it here

what is test case 11 in Div2 B?

4

a b c d

10

20 d c c c c c b b b b b a a a a a a a a a

20 d c c c c c b b b b b a a a a a a a a a

20 d c c c c c b b b b b a a a a a a a a a

20 d c c c c c b b b b b a a a a a a a a a

20 d c c c c c b b b b b a a a a a a a a a

20 d c c c c c b b ...

How does the answer(p) come 1?

I got it.

When will editorial be available?

I didn't understand the definition of "clear" matrix in "Clear Symmetry." "Clear" means that no two or more adjacent "1"s never appear? Thank you in advance.

Thanks for the advance. :P

I wanna see my name above! This will really improve my Programming skills.