I previously did not understand why some people write ps[j] = (ps[j — 1] + dp[pidx][j] + MOD) % MOD when I read others code, but I understand it now. Thanks a lot for your explanation.

If the β sign is removed, the logo looks like that:

I do not have a strong sense of beauty so I do not know which one is more beautiful :(

Maybe you are right.

For 437B — The Child and Set, I think you need to prove why all the numbers chosen are distinct. If the numbers are not distinct, the solution does not fulfill the problem statement. Here is the prove:

Let a × 2^x = c for some positive odd integers a and some positive integers x and c

If b × 2^x - y = c for some positive odd integers b and y ≥ 1,

$a \times 2^y = b$ can be true only when y = 0. So, this is always false. So, the number chosen are always distinct.

(Sorry, I am not familiar to the latex function in Codeforces. I do not know how to use align and why the formula in the bottom left hand corner does not show correctly.)

I think I will write a plugin for vim later so that I can read problem statements, do coding and submit the solutions in vim and throw away the web browser :)

Should it be O(n*m+q*(n+m))?

I will do that from now on.

Yes, I agree that their solutions are very easy to read, but most masters' are not.

I think that my coding style is quite good (Am I too arrogant?). Unfortunately, I am only a newbie and you can learn nothing from me. I can hardly read most masters' code as they use a lot of macro, and the variables are named casually.

I am sorry to hear that you feel uncomfortable with the time.

However, I like the time very much :) It is 15:00 in Hong Kong (UTC+8), but I will be at school as it is Friday... The usual time of contest will be at 23:00 in Hong Kong and I can't help falling asleep at that time.

I hope that the time could be modified so as to cater most people's need.

What do you mean?

Me too! I received the email 4 hours and 4 mins after the competition had started.