Hello Codeforces!

I'm glad to announce that we will be having Round 19 of MathMash today at 17: 15 UTC. The round has been prepared by Snpushpita, Joydip, thanicsamin, rah4920 and DrSwad.

The round will consist of 8 problems, as usual, to be solved within 2 hours.

Points distribution for the problems are decided as 750-750-1250-1500-1750-2500-2500-3000

We're inviting you all to join us in the contest. Hopefully we'll have a fun and successful round.

Update: The round has been postponed by 15 minutes as it appears that the Google Code Jam Distributed Round ends exactly at 17: 00 UTC.

A few details about the contest:

• In order to participate in the contest, you need to register first. Kindly follow this link to do so. Registration deadline has been removed from the contests. So now, you can register at any time before the contest ends.

• I know this announcement is being placed in a coding website, but unfortunately using computer programs for MathMash contests is not allowed. We are trying to reward users' math skills with high ratings as there are not many sites that do this yet. We also try our best to set up the problems in such a way that any trivial brute force approach isn't supposed to work (for the mediocre/difficult problems).

• Time-penalty is applicable for the contest: Each problem is given an appropriate number of points, which will be visible when the round starts. Participants will gain that many points — the time penalty after successfully submitting to a particular problem. The later the problem submission occurs, the more points being deducted due to time penalty.

• The round is rated; which means that if you participate in the contest, your rating will be updated at the end of the round based on your rank in it. But you won't be considered as participating in the round if you don't submit any answer at all, even if you're registered for the contest.

• +27

 » 2 years ago, # |   +6 It's already 2nd round that I participated in and I'm really thankful for this exciting kind of competition. Although I enjoyed it very much, I think that something about those competitions should be definitely changed. 1) Today my friend solved geometry with that kind of reasoning: "hmmm, seems like if CD is just 6, then AD should be somehow small" and then he guessed "answer = 11" very soon. This would have never happened if conditions were like "CD = 600". Setting constants in problem as big as possible would make it difficult to guess the answers.2) " using computer programs for MathMash contests is not allowed." -- this rule can't be controlled, and some people would of course break it (somebody just uses WolframAlpha, somebody solves almost everything with programming) and get high places. What can be changed about it? Today's problem H (about a, m, n ≤ 2018, am + 1|an + 203) may be solved in very straightforward way in any language with long arithmetics: ans = 0 for a in range(2, 50): ____for m in range(2, 50): ________for n in range(2, 2018): ____________if a ** n + 203 % a ** m + 1 == 0: ________________ans += 1 print(ans) However, computing might help with handling cases like "a, m, n ≤ 10" which one had to perform on his own today. If one sets constants in problem as big as possible (like a, m, n ≤ 20000018) then it wouldn't really affect correct solution, but all "dumb" solutions would definetely fail. Hope to see those regulations of mathmash (truly beautiful platform) improved!