Codeforces Round #457 (Div. 2) Editorial

Revision en1, by STommydx, 2018-01-19 21:45:30

I would like to take this opportunity to express my deepest apology to all of you who take your own precious time to participate in this unrated round. Also, apologies to vintage_Vlad_Makeev who really helped a lot in preparing the round. As the main author of this round, I'm undoubtedly responsible for the mistake that not writing a brute force solution to test the correctness of the intended solution.

I hope all of you can learn something from the contest. Do not claim a greedy solution absolutely correct (like me :C) unless you have proved it. On the bright side, I'm really glad that some of you found problem D and E interesting as said in some comments in the announcement blog post.

Just a little fact: The original div2B problem was a harder data structure problem which involves a slightly complicate mathematical proof (which the current div2B doesn't have :C). We replaced it because it is too difficult for div2B as the coordinator suggested.

#### 916A - Jamie and Alarm Snooze

idea: STommydx, preparation: southball

#### 916B - Jamie and Binary Sequence (changed after round)

idea: southball, preparation: STommydx

Working in progress!

#### 916C - Jamie and Interesting Graph

idea: STommydx, preparation: STommydx

#### 916D - Jamie and To-do List

idea: STommydx, preparation: STommydx

#### 916E - Jamie and Tree

idea: longhuenchan, preparation: longhuenchan

#### History

Revisions

Rev. Lang. By When Δ Comment
en10 STommydx 2018-01-20 15:42:53 158 Updated E editorial
en9 STommydx 2018-01-20 11:18:08 2604 Added E tutorial
en8 STommydx 2018-01-20 10:17:13 317 Added my implementation
en7 STommydx 2018-01-20 08:09:28 681 Added B editorial (published)
en6 STommydx 2018-01-20 07:13:01 1117 Added D tutorial
en5 STommydx 2018-01-20 04:09:14 2 fix typo
en4 STommydx 2018-01-19 23:15:03 6 Tiny change: 'me? As $x <= 60$, $hh$' -> 'me? As $x \leq 60$, $hh$' (saved to drafts)
en3 STommydx 2018-01-19 23:14:17 95 Tiny change: 'answer is 390 where $x ' -> 'answer is$390$where$x ' (published)
en2 STommydx 2018-01-19 23:04:28 1519 Added A and C tutorial
en1 STommydx 2018-01-19 21:45:30 1539 Initial revision (saved to drafts)