Unfortunately, we had a bug in our interactor of the interactive problem.
The interactor contains the following code:
if (y < x) t = -1; else if(y > x) t = 1; else t = 0; if(!p[q % n]) t *= -1; cout << t << "\n" << flush;
This is the opposite to the statement. However, it turns out that this error doesn't causes any harm for solving problem — it actualy just inverts the pattern, selected by judges. This also wasn't noticed during testing, by the same reason — the error is not visible to the user code.
But it may cause unexpected behaviour for hackers -- since they write the pattern themselves.
We are very sorry for this error and decided to do the following:
- The round will be rated, because very little people (maybe even zero) got affected (the people, who made incorrect hack)
- If you made a hack, which turned to be incorrect due to the error, we will cancel your - 50 points and recalculate your rating afterwards. Please PM me if you have such a hack.
We are very sorry again. This is a huge lesson to us to be more attentive.
I hope you enjoyed the round!