DMOPC '19 October Contest

Contest is over.

03:00 window between October 11, 2019, 0:00 EDT and October 14, 2019, 0:00 EDT

The authors of this contest are george_chen, little_prince, KevinWan.
Special thanks to Kirito, AvaLovelace for testing and feedback on the problems.
This contest will be rated for participants who submit at least once.
There are 7 problems in this contest.
- Partial scoring is enabled for some or all of these problems.
- The pretest system will not be used for this contest.
- There is no submission limit for any of these problems.
The contest format is AtCoder.
- The maximum score submission for each problem will be used.
- Each submission before the first maximum score submission will incur a penalty of 5 minutes.
- Ties will be broken by the last score altering submission time.
The scoreboard will be visible for the duration of the contest.

Welcome to the second DMOJ Monthly Open Programming Competition of the 2019-2020 season!

The problem writers this time are george_chen, KevinWan, little_prince.

This contest was audited by AvaLovelace and Kirito.

Please note that this contest will be full feedback.

This round will be rated for all participants who submit at least once.

Before the contest date, you may wish to check out the tips and help pages.

This contest will consist of 6 main problems, the difficulty of which may range anywhere from CCC Junior to CCO level.

This contest will feature a 7-th problem (Problem 0) for students who are just getting started with programming.

Some problems offer partial marks in the form of subtasks. If you cannot solve a problem fully, we encourage you to go for these partial marks.

You will have 3 hours to complete the contest. After the contest window begins, you may begin at any time. Once you enter the contest, your personal timer will start counting down and you will be able to submit until 3 hours from when you started, or until the hard deadline (midnight EDT of Oct. 13th), whichever comes first.

After joining the contest, you proceed to the Problems tab to begin. You can also go to Users if you wish to see the rankings.

We have listed below some advice as well as contest strategies:

Ties will be broken by the last submission time that increased your score plus penalties. The first submission time of your highest score will be used.
Each non-AC (excluding Compiler Errors) submission will incur a penalty of 5 minutes.
It is not guaranteed that the problems will be in order of increasing difficulty. Reading all of the statements is recommended.
Remove all extra debugging code and/or input prompts from your code before submitting. The judge is very strict — most of the time, it requires your output to match exactly.
Do not pause program execution at the end. The judging process is automated. You should use stdin / stdout to perform input / output, respectively.
It is guaranteed that all the problems will be solvable with C++.

Clarification requests for the contest must be routed through the clarification system provided on DMOJ, and not through other channels including but not limited to Slack and Discord.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in your rating being impacted negatively. Such behavior includes, but is not limited to:

Registering for the contest with at least two accounts.
Participating in the contest with an account that is not your primary account.
During the contest window, talking about the contest in more detail than answering a yes/no question about whether one participated in the contest. This includes, but is not limited to, posting spoilers about the contest and public speculation of the contest.
Attempting to exploit bugs in the platform to subvert the constraints of the contest.

Punishments may include performance being unrated or, for more serious infractions, being forcibly ranked at the bottom of the scoreboard.

At the end of the contest, you may comment below to appeal a judging verdict. In the case of appeals, the decision(s) of DMOJ staff is final.

Problems

Problem	Points	AC Rate	Users	Editorials
DMOPC '19 Contest 2 P0 - Roller Coaster	3	62.4%	325
DMOPC '19 Contest 2 P1 - Box and Whiskers	5	16.5%	252	Editorial
DMOPC '19 Contest 2 P2 - Squares	7	49.2%	421
DMOPC '19 Contest 2 P3 - Selection	12	38.8%	164	Editorial
DMOPC '19 Contest 2 P4 - A Greedy Problem	15p	20.6%	85	Editorial
DMOPC '19 Contest 2 P5 - Connections	20	6.9%	12	Editorial
DMOPC '19 Contest 2 P6 - Two Roots	20p	11.8%	24	Editorial

Comments

0

dsv2075 commented on Nov. 8, 2019, 11:38 a.m.

where I can find the solution? Editorial link is not working

11

Rimuru commented on Oct. 21, 2019, 1:48 p.m.

Due to a change of P4's data, I have publicized another version of it so that it does not affect the leaderboard here.

3

002 commented on Oct. 22, 2019, 12:23 a.m. ← edited →

Now my $\mathcal{O}(Q T + N T \log Q)$ ~\mathcal{O}(Q T + N T \log Q)~ solution can't pass :(

5

Ninjaclasher commented on Oct. 21, 2019, 3:09 p.m.

decreases time limit instead of augmenting test data

3

wleung_bvg commented on Oct. 21, 2019, 4:06 p.m.

At least data was correct

3

magicalsoup commented on Oct. 21, 2019, 5:16 p.m.

Are you still mad about A Harder Contest?

3

Plasmatic commented on Oct. 21, 2019, 5:48 p.m. ← edited →

YIKES

-14

wleung_bvg commented on Oct. 21, 2019, 2:00 p.m. ← edited →

Except data doesn't seem to be augmented by much ... $\mathcal{O}(NQT)$ ~\mathcal{O}(NQT)~ still passes

Edit: okay seems to be fixed

This comment is hidden due to too much negative feedback. Show it anyway.

17

Tzak commented on Oct. 21, 2019, 2:11 p.m.

"Yeet" -george_chen

16

imasheepow commented on Oct. 20, 2019, 6:41 p.m.

Are these problems going to be publicized?

9

Rimuru commented on Oct. 21, 2019, 1:48 p.m.

Yes.

6

stringray commented on Oct. 15, 2019, 7:03 a.m.

how to solve p5 connections

-14

magicalsoup commented on Oct. 15, 2019, 1:32 p.m.

Centroid Decomposition.

This comment is hidden due to too much negative feedback. Show it anyway.

13

Swarley commented on Oct. 14, 2019, 5:51 p.m. ← edited →

weak P4 test data? slight optimizations allow $\mathcal{O}(NTQ)$ ~\mathcal{O}(NTQ)~ solutions to pass.

4

verybadallen commented on Oct. 14, 2019, 4:53 p.m.

OPEN 12 HOUR HACKING PERIOD :blobhammer:

7

verygoodallen commented on Oct. 14, 2019, 4:56 p.m.

Bad.

13

Darcy___Liu commented on Oct. 14, 2019, 7:05 p.m.

verygood

1

Saikat commented on Oct. 14, 2019, 11:50 a.m.

I'm new here. How do I submit solutions to these problems after the contest and check other people's solutions like in CodeForces ? I wish to upsolve them.

14

crackersamdjam commented on Oct. 14, 2019, 12:30 p.m. ← edited →

You may click virtual join to start a virtual session that simulates the real contest. Unfortunately, you will not be able to view others' solutions until the problems are released (outside of contest) AND after you solve the problem(s) in question.

1

Saikat commented on Oct. 14, 2019, 4:58 p.m.

Thank you for your reply. But I have already participated in the contest in real time. Will I be allowed to participate in Virtual Mode ?

5

alextxu commented on Oct. 14, 2019, 5:15 p.m.

Yes.