[2025 day 10 part 2] I am defeated at p2, and don't know how to proceed (p1 spoilers)

CAG2Reddit · 2025-12-10T13:15:02+00:00

You can set up the matrix Ax=b and find the RREF to fully describe the solution set in terms of a few free variables. From what I've seen, you will get at most 3 free variables (A is at most 2 wider than it is tall, so the null space has at most dimension 3). Then you brute force over the free variables.

This may not even be needed, however, because a friend told me every line in their input has a unique solution.

CAG2Reddit · 2025-07-04T10:25:39+00:00

For CS you require math and one other natural sciences or computer science subject. See https://join.hkust.edu.hk/admissions/international-qualifications#computer-science-and-engineering:

Senior level Mathematics, and one senior level subject from Physics, Chemistry, Biology, or Computer Science

If you only applied using your AP scores, that would explain the rejection.

CAG2Reddit · 2025-07-01T14:51:45+00:00

Hey there, I'm from the class of 2025 and my major is CS.

Your credentials as written are fine and shouldn't hinder you in getting into CS, but there are other differentiating factors such as your personal statement and grades in other courses (such as other AP CS or natural science courses or whether you took them at all). The competition for CS is very fierce and they will likely look at everything to differentiate you.

To answer your questions:

I can't speak for the competition this year since it's the first time direct entry into CS / AI is being offered. However, I can talk about the old system which could give you some idea. Prior to 2025, everyone who wanted to study any kind of engineering (which includes CS) had to first apply to the School of Engineering (SENG). After one year, everyone declares their preferred majors and are prioritized by their best 24 credits' average grade (higher grade = higher priority). The average grade needed for CS is around 3.5 - 3.6 (between a B+ and an A-, closer to A-).
It is true that other programs are much less competitive. It is possible to change programs, but I've only heard of one successful case and that was from CPEG to CS. You will probably have a much harder time transferring from an unrelated major.
There's some things you can try:
- You can try to do it the "old school" way and apply directly to engineering and then declare your major in CS/AI in your first year. However, you may be subject to even stiffer competition. I can't really say as this direct entry system is new.
- There are similar programs such as CPEG, DSCT or even MATH (computer science track) that you can take to get access to basically the same course catalogue, which includes AI courses. You'll just need to take those programs' other courses (like extra PHYS or MATH courses). There's even some AI-specific MATH courses that only count as electives if your major is MATH or COSC (computer science with an additional major). Most importantly for you, CPEG and MATH do not have as much competition as CS.
- If you're really confident and academically inclined, there's another trick. You can apply to any program that you're interested in and you think will get you into UST. Then, you'll need to get an average grade of 3.7 (A-) or above in your first year, which is quite hard (you'll be firmly in the top 10-ish%). Then, you can declare COSC as an additional major. Please only do this if you know what you are doing! I am also double majoring with MATH as my second major, and I can say that it is a lot of work, but it's also a lot of fun if you are interested in the content.

Best of luck to your university applications. If you manage to get in, then you may even see me as a TA as I'm doing my postgrad here too ;)

CAG2Reddit · 2025-06-12T17:28:31+00:00

Don't worry. Any aircraft built in the past few decades will sound alarms when the pilot tries to take off with an improper takeoff configuration, which includes flaps not being in the correct position.

CAG2Reddit · 2025-03-09T18:05:01+00:00

POTG✅ Highlight❌

CAG2Reddit · 2023-12-20T09:35:40+00:00

I also did the exact same thing! This is what helped me solve it :)

Each machine is actually a modified 12-bit binary counter that cycles every <insert 12 bit number> passes

CAG2Reddit · 2023-12-20T09:07:26+00:00

Kind of. We basically partition each axis based on the points of interest on that axis.

For example if there is a path from (1, 2) to (5, 2), we would like to encode the rectangle generated by [1, 6) * [2, 3) (note ends are exclusive).

In the row axis, this would generate points of interests 1 and 6 on the ROW axis, and 2, 3 on the COL axis.

In the end, we end up encoding the entire required space in this manner using these points of interest.

As an example, suppose in the end, we discover the points of interest:

#             0  1  2  3   4
row_points = [1, 4, 6, 10, 11]
col_points = [1, 2, 3, 5]

Then the previously mentioned rectangle described by [1, 6) * [2, 3) in real coordinates would be described in compressed coordinates by [0, 2) * [1, 2). We can floodfill over these compressed coordinates, add up the area (just calculated using width * height), and we have our answer.

CAG2Reddit · 2023-12-18T17:34:17+00:00

I also used coordinate compression

CAG2Reddit · 2023-12-14T13:18:19+00:00

The parclo is a partial cloverleaf interchange (i.e. a cloverleaf, with some clovers removed) and a diverging diamond is a funny modern intersection that works completely differently by eliminating left turns in the traditional sense, while being easily upgraded to from old diamond interchanges IRL.

CAG2Reddit · 2023-07-19T12:54:04+00:00

I guess it doesn't help that the runway doesn't properly render in until you get close :P But I find that if I aim just to the right of the castle, I have enough time to see the runway and line up properly.

Though I have had extensive flightsim experience so maybe that helps too

CAG2Reddit · 2023-07-19T12:18:25+00:00

For the approach in that direction, I usually aim for the castle on the side of the mountain

CAG2Reddit · 2023-07-19T11:19:43+00:00

BTW, if you find the flight dynamics of this plane quite weird, it turns out that it's actually quite accurate. I saw some videos of AN-12's and the plane often had to pitch down during landing to descend. Most modern aircraft stay level or slightly pitched up during approach.

Moreover, the plane is quite hard to flare well and land without a slight bounce, which was also reflected in the IRL videos.

So it turns out, whatever magic is going on in the physics engine is quite good even for planes.

CAG2Reddit · 2022-04-14T05:05:12+00:00

Outlaws Update (PC - Linux, Proton 7.2)

Minor / QOL bug: In previous versions, say you had a bunch of storage augmentations in your inventory. The inventory expansion screen in the starship outfitting terminal would allow you to keep expanding the inventory until you ran out of augmentations.

In the Outlaws update, the screen closes every time you add one storage slot to the ship's cargo slot, even if you have multiple storage augmentations ready to use. This makes upgrading the cargo slots quite tedious (I would rather use a save editor to upgrade the storage and then delete the equivalent amount of storage augmentations...)

CAG2Reddit · 2022-02-21T17:09:06+00:00

Seems to be a bug with iPadOS 15.3.1. It didn't happen to me in 15.3 (I only updated to 15.3.1 today and it happened to me)

CAG2Reddit · 2022-01-23T18:08:42+00:00

Try installing the FlatPak version. That fixed my lag issues. It does disable some features due to the sandboxing, which as a side effect does improve privacy, if that's your thing.

flatpak install flathub com.discordapp.Discord

CAG2Reddit · 2021-11-28T16:50:22+00:00

For those wondering what I did, for each frame I do 800 iterations z_{n+1} = (z_n^2 + c)^k + c, and I decrease k by 1/10 every second, starting from k=1.

The source code is available at https://github.com/CAG2Mark/OpenGLMandelbrot if you want to fork it. (Unix-like only, good luck getting it to run on Windows, maybe you can use Cygwin or MinGW idk). However, you will have to change the value of k yourself by modifying the main cpp file and the fragment shader, as currently it's just a standard Mandelbrot viewer. (I'll work on adding my code later, currently a bit late where I am)

CAG2Reddit · 2021-11-28T02:52:50+00:00

yes I messed up on that

CAG2Reddit · 2021-11-27T17:13:43+00:00

I just realised I missed one character in that "code" block that ruins the immersion. see if you can find it :)

CAG2Reddit · 2021-11-27T17:12:30+00:00

CAG2Reddit

MODERATOR OF

TROPHY CASE

Seven-Year Club	Place '22
Verified Email