Sharing Candies
Problem Idea: Cisco Ortega
Story: Amanda Lim
Test Data: Amanda Lim
Tester: Cisco Ortega
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): The first problem should technically be solvable even without loops, hence the fixed n=7 number of packs.
Hans Gets Disqualified
Problem Idea: Cisco Ortega
Story: Cisco Ortega
Test Data: Cisco Ortega
Tester: Paolo Estavillo
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): I apologize for the oversight in that I did not consider that “incident(s) of cheating in the past” would, beyond just flavor for the story, cause people to filter only for dates that had occurred in the past with respect to e.g. Datetime.now(). This interpretation of the phrasing did not occur to any of the scientific committee members.
Ultimately it might have been better to just have the years only go up to 2022 anyway, just to remove all possibilities of ambiguity.
The problem story loosely references the Hans Niemann cheating allegations following his September 2022 match against Magnus Carlsen.
Inverse Ferb Latin
Problem Idea: Paolo Estavillo
Story: Paolo Estavillo
Test Data: Paolo Estavillo
Tester: Amanda Lim
Editorial: PDF (by Paolo Estavillo)
Remarks (Cisco): This problem ended up being harder than anticipated. Of course, NOI.PH Elims problems aren’t necessarily sorted in increasing order of difficulty, but I make an effort for the first few problems to have a nice curve.
This is a “pen and paper” problem. The running time of your algorithm isn’t really a concern, and really the problem barely uses loops at all. However, it seems that ironing out the logic and hunting down various edge cases turned out to be more than tricky enough to make up for it. If I could reorder the set, I would put this after Amogus and Rule of Three.
The problem story directly references the animated TV series Phineas and Ferb. Specifically, it (clearly) references the episode Ferb Latin.
Amogus??????????
Problem Idea: Cisco Ortega
Story: Cisco Ortega
Test Data: CJ Quines
Tester: James Bryan Francisco
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): We really couldn’t come up with nice subtasks for this one.
The problem idea was inspired by the Matt Parker video, “I found Amongi in the digits of pi!”.
The problem story references a past problem from NOI.PH 2021 Elims.
Zoom Proctoring
Problem Idea: Aldrich Asuncion
Story: Aldrich Asuncion
Test Data: Aldrich Asuncion
Tester: Mark Ong Yiu
Editorial: PDF (by Aldrich Asuncion)
Remarks (Cisco): Whenever Aldrich and I discuss this problem, we always sum up our solution as “sungka” (highlight white text to view a spoiler). It’s the only way I can think of summing up our solution in one word.
Remarks (Aldrich): There are many ways to form the construction, and I hope those of you who got Accepted were able to justify the correctness of your construction in some way.
Many submissions involved sorting the students using some built-in sorting function to sort students by their school, which runs in O(n lg n) time. But since the number of schools is less than or equal to n, linear-time sorting algorithms, such as counting sort or bucket sort, are feasible and technically better. Strictly linear time was not required to pass the time limits, however.
Rule of Three
Problem Idea: Cisco Ortega
Story: Cisco Ortega
Test Data: Dan Baterisna
Tester: Cisco Ortega
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): This problem could have been made harder (see notes at the end of the editorial), but we decided to leave it in its current state in order to smooth out the score distribution. Of course, one could say, “But isn’t that what subtasks are for?”, and my answer is: Well, yes, but I think people find it motivating to see a nice crisp 100/100 :))
I Really Hate Olympiad Algebra
Problem Idea: Cisco Ortega and Vincent Dela Cruz
Story: Cisco Ortega
Test Data: Miko Surara
Tester: Vincent Dela Cruz
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): If you can get 93 points on this problem, then I would essentially consider it “solved”… unless you’re a math nerd and you like learning obscure advanced tricks! See the editorial for more details.
In case you missed it, the initials of Princess Mattea Oleifera give us PMO, whereas Neumann Philips is meant to represent NOI.PH (the “Neu” in Neumann is actually pronounced “Noy”).
We also want to make it clear that the title is very tongue-in-cheek and meant to be from the perspective of Neumann in the story; NOI.PH does not “hate” Olympiad Algebra!
The World is Round
Problem Idea: Miko Surara
Story: Payton Yao
Test Data: Miko Surara
Tester: Andrew Ting
Editorial: Coming soon!
Remarks (Cisco): The specific phrasing of “without form, and void” was a deliberate choice, in order to directly quote the translation of tohu wa-bohu in the King James Bible.
Who Doesn’t Love Sliding Puzzles?
Problem Idea: Miko Surara
Story: Cisco Ortega
Test Data: Miko Surara
Tester: Cisco Ortega
Editorial: Coming soon!
Remarks (Cisco): The story in the problem is quite barebones and could apply to any (of many) video games which shoehorn random minigames into the main plot; however, I specifically had this skit by ProZD in mind while writing the story.
.img of the Artist as Filipino
Problem Idea: Cisco Ortega
Story: Cisco Ortega
Test Data: Cisco Ortega
Tester: Dion Ong
Editorial: PDF (by Cisco Ortega)
Remarks (Cisco): This problem is a continuation of “Image of the Artist as Filipino” from the Abakoda 2022 Long Contest. Both problem titles are a play on “Portrait of the Artist as Filipino“, a literary play by Nick Joaquin, one of the Philippines’ National Artists.
For another hard data structure problem with similar vibes, you can check out GGVV from the 2016 UP ACM Algolympics (you may need to register into the Hackerrank “contest” first, in order for the url to work).
Osmosis (Version Alpha)
Problem Idea: Vernon Gutierrez
Story: Cisco Ortega
Test Data: Vernon Gutierrez
Tester: Ivan Tan
Editorial: PDF (by Vernon Gutierrez)
Remarks (Cisco): The problem scenario and story are both hugely inspired by the King of Clubs game of the same name from the manga/Netflix live-action series Alice in Borderland. If you intend at all to watch Alice in Borderland, then please don’t spoil yourself by reading the Wiki page!
If it felt like “Osmosis” was unrelated to the problem statement, it’s because the original game had a mechanic where you could battle the enemy team for points (but this dynamic was cut entirely from the NOI.PH version of the problem).
Accomplice to the Cutest Bunny in the World
Problem Idea: Dan Baterisna
Story: Payton Yao
Test Data: Dan Baterisna
Testers: Ivan Tan and Vincent Dela Cruz
Editorial: Coming soon!
Remarks (Cisco): The picture of the bunny used in the problem statement is in fact the real pet bunny of Payton Yao. His name is Oreo McFluffy! His trouble-making behavior in the problem is a reflection of how he acts in real life.
Pre-in-Post
Problem Idea: CJ Quines
Story: Cisco Ortega
Test Data: CJ Quines
Testers: Cisco Ortega
Editorial: Coming soon!
Remarks (Cisco): Truth be told, this problem was intended to be one of the hardest problems in the set to get a full 100 points in, because getting a formula that runs in sub-quadratic time uses a lot of advanced math. However, once we realized the “cheese” solution (see Editorial when it’s out), we decided it was both funny and educational enough to leave it as is.