Yeedrag's website :D

Note: This blog was written with the help of GPT-5. OASIS is a 3-day workshop in Berkeley, hosted by Kairos, that brings together university AI safety organizers to exchange ideas and strengthen their groups. Day 0 Day 0 had quite a hectic start. First, I took a 2-hour plane from Madison to Dallas, waited for 3 hours — with another 30-minute delay — and flew to SFO. I opened my Uber app after landing and realized that the drive between SFO and Berkeley was another 40 minutes, which I could’ve ea ...

Prerequisites: Time complexity, basic coding knowledge Dynamic Programming is considered one of the more challenging topics in competitive programming and coding interviews. Unlike other topics, dynamic programming can appear anywhere and is often paired with other algorithms. I get more questions about DP than any other topic, so I decided to write a blog teaching DP from scratch. This blog is for readers who aren’t comfortable with DP and those preparing for coding interviews, so it won’t incl ...

Well, it’s been a month since the semester ended, and I think I should maybe write some stuff about my sophomore year! I’ll start from recaping what my goals were in my freshman year, do some recap for sophomore year, and finally give some goals for junior year. Recap on Freshman Goals Okay, so honestly now I look back at what my goals were, they are quite ambitious and funny, things clearly did not go completely towards what I expected. Maintain 4.0 GPA ✓ This one was not that difficult to acco ...

Hey guys! Well the semester ended a while ago, and I was originally planning to make a summary of my semester, but I’ve decided to write a short blog on an expensive eye mask I bought a while ago. To start, I always had some problems with sleeping. I fall asleep slowly and I often don’t have a good quality in sleep. One day, I saw on the internet about people recommending an eye mask from Manta, saying that it helped their sleep quality a lot. I was really tempted after seeing all the good revie ...

Hey guys! It’s been a while since I updated… again lol. It has been busy (but also not that busy? I’m just a bit lazy I guess), so I think it’s a pretty good time to make a new blog for some short updates. I’ll split it into a couple sections so that it’s easier to read. Research So good news is that my IEEE big data paper is now on their website, and that my other paper that I worked on since high school is finally accepted to IJGIS (one of the top GIS journals) after 2 years! It took such a lo ...

Happy new year! :D This year felt so short compared to before, maybe because im getting old, so time flows faster in perspective? Well, first things first, lets look at my previous new years resolution: ✓ Maintain 4.0 GPA: I was able to maintain a 4.0 in both semesters suprisingly easy. The math classes that I thought I would struggle like honor linear algebra or number theory didn’t really pose that much of a threat to me, and I actually felt my load was quite managable most of the time! ✓ Dou ...

Hey Yall! It’s been quite a while (again), I finished the first semester of my sophomore year! I’ll be giving some recaps later, but let’s read some papers first :D For some context, I took a graduate LLM class this semester, and there were alot of papers that were mentioned, so I wanted to go over them thoroughly throughout the winter break. In this blog, I will be covering BERT, RoBERTa and LoRA. I was going to do “Attention is all you need” but I decided o maybe put that as a individual blog ...

This is a simple blog post talking about my REU experience at UW Eau Claire in summer 2024. First, I want to explain what REU is. Research Experience for Undergraduates (REU) is a program that provides research opportunities for undergraduates in various fields of science and engineering. Essentially, it’s a summer research program for college students funded by the National Science Foundation (NSF). It’s actually a pretty competitive program, and I was lucky to be selected just before giving up ...

Time flies! Can’t believe it’s already been a year since I graduated high school, and I already finished my first year in university. I still remember back then I was so hopeless because I got rejected by Cornell or UIUC, and instead had to come to a university I just found out during college application, but everything seems to be alright now, and even better then I would ever expect! Anyways, this blog is to revise what I did in freshman year, and some hopes for my sophomore year. Academics I ...

Hey guys! Since class is over and im back at Taiwan, I want to share some learning on some mathematical foundations for ML. I’m not sure what I want to cover nor how deep I want to cover, although I’ll try to make this as approachable for people. Prerequisites: Matrix Operations and Identities, Basis, Diagonalizability, Eigenvalues and Vectors, Variance and Covariance What is PCA and Why? Principal Component Analysis (PCA) is a powerful statistical technique commonly used for dimension reduction ...

Hey guys, life has been pretty busy lately and tough so I haven’t updated in a while, so I decided to write a short blog about some CM+ (>=1900) problems I solved in CF lately. The difficulty will we roughly sorted by how hard I feel it is. CF 1923D. Slimes (1800) I know this question is only 1800, but I feel like it deserves at least 1900. The high level idea for this problem is to find how many slimes we need to accumulate from the left/right to eat this slime. Formally, for each index iii, ...

For this week, I decided to read a trio, the trio of regional based CNNs. R-CNNs are usually used in object detection tasks. Theres also Mask R-CNN that can do segmentation but I won’t talk about that (or maybe I will). Rich feature hierarchies for accurate object detection and semantic segmentation (2013) This is the first paper that proposed the idea of using regional proposals with CNNs to do object detection. The whole framework is quite interesting, and I will introduce them one by one. Re ...

For the first week of my goal of reading AI paper, I chose three very classic CV papers to read from. Lets see what we can learn from reading these very old yet groundbreaking papers! I’ll roughly talk about the main important parts of the papers and add my own thoughts and opinions. Details can be found in the original paper that I’ve linked in the title. ImageNet Classification with Deep Convolutional Neural Networks (2012) This is the paper about the well-known model “AlexNet”. I would say th ...

This is honestly something I’ve been wanting to do in a while now. I feel like one of my biggest weaknesses is the lack of knowledge in SOTA methods. In a field where there are ground breaking researches being produced everyday, I need to be equipped with the newest knowledge at every moment. I will probabily make like a summary each week of the papers I’ve read (likely 2 ~ 3 papers), and I think I will start from classical computer vision papers (YOLO, ResNet) and extremely influential papers ( ...

The workload in school has ramped up quite quickly recently, so listening to music really helped me lessen my stress. I also discovered alot of great songs that I enjoy recently, so I wanted to share them here. Japanese 【初音ミク×GUMI×鏡音リン】PaⅢ.SENSATION Miku and GUMI and Rin? Sign me up! まにまに / 初音ミク I really like the part at 3:08, its just so epic and I enjoy it so much!! バースデイ / 可不 Its so hard to find a bad KAFU song… ロクデナシ「眼差し A really soothing and warm song imo. ピノキオピー - ノンブレス・オブリージュ feat. 初音ミク O ...

A while ago, someone in a server asked for help with this problem: Equality Etiquette I solved it while I was on the airplane coming back to the US, and I thought it was a really interesting problem! I’ll give my detailed explaination for this problem here: The first thing I noticed immediately, is that the operations are not as complicated as it seems. We only care about making the difference of the two numbers 0, and we can notice that adding a number to the bigger number does the same as subt ...

Hey guys! There are quite alot of things that happened in Janurary, so why not I make a quick recap? The first biggest thing I done was skipping calculus 2 & 3 in 1 month without much prior experience. The reason I wanted to do that is because I’m seriously considering double majoring in math, and so I wanted to take proof-based linear algebra instead of computational based ones, which requires multivariable calculus (The computational one needs calc 2 too, so I kinda had to at least pass on ...

Heya~ before talking about this problem, I just wanna say that I didn’t insta fail my resolutions yay! I’ve been doing 5 problems everyday, and grinding very hard on math. I think I should also do some virtuals on top but we can start slowly :D I want to talk about this problem, because it caused me alot of trouble due to a silly mistake XD, other than that it was a pretty standard problem. CF 1904D. Set To Max (Hard Version) There are two versions of the problem, with the difference being n≤1e3 ...

Hey guys, sorry for not updating in a while, just couldn’t really find the time or put in the effort to type a new blog TMT Well uh I’ll talk about ICPC first. Unfortunately, we got 3rd place in regionals, but because first place was also from our school, we couldn’t qualify for NAC. Not gonna lie, its kind of my fault that I’m way too weak compared to my teammates, they definitely deserve to get in NAC, and I kind of pulled them back. Sorry Boying, I wasted your last chance in ICPC. After that ...

Ehhh, all of these should’ve been separate blogs. But I was too lazy, and I don’t want to do my art assignment so here we are. 10/24 Round 904 (Div 2) Virtual Virtual Rank: 997 (According to Codeforces Anytime) AC Count: 3 / 5 This was one of the contests held in 10/22. pA and pB aren’t really hard so I’m not gonna go over them here. pC was a interesting one, because it is really similar to E2. Array and Segments (Hard version), and I tried to just do the segment tree solution I used in it, but ...

Okay, I know yesterday I said I’m going to grind a mashup every morning, and I didn’t do it today, because today is Meta Hacker Cup Round 2! This blog will be a short recap and summary for my meta hacker cup experience. 9/22 ~ 9/27 Practice Round Rank: 1711 / 12138 AC Count: 2 / 5 (FST 2) This is a round made for understanding how the contest works (and also making me realise how weak the pretests are). A1 and B are extremely simple, B even only has 4 lines of code! Although A2 and C has weak pr ...

I’ve decided that every morning, I will make a random mashup of 5 problems in a suitable range, and I will try solving all of them and check how much time I used. (I will introduce the problem in the order I solved) Todays Mashup (range 150015001500 ~ 200020002000) Total Time: 2h 7m 58s Total WA: 10 (bruh) CF 1217B. Zmei Gorynich WA count: 1 This problem is pretty easy, We want to choose the largest di−hid_i - h_idi​−hi​, and only use it. We can also use the highest damage one to deal the final ...

Our team is starting to practice for the regionals, so this is just a documentary of our performances. 2018 East Central NA Regional Contest Virtual Rank: 5 This contest was extremely tedious and annoying. Most problems are really easy, but extremely implementation heavy. It was so bad that we actually just gave up and went to get food after the fourth hour. I really hope our regional wouldn’t look like this, or else I might cry haha. 2019 North Central NA Regional Contest Solved: 11/11 Virtual ...

I’ve discovered alot of great songs that I enjoyed, some I thought to share some here. 月詠み『逆転劇』 This one I replayed over and over these couple of days. It really makes feel feel powerful, and gives me the feel that I shouldn’t give up. The lyrics are also awesome and really inspiring. Apparently it’s from an anime, might actually check it out because of this song (I watched steins gate because of the music, and it became one of my favorites) 永遠の不在証明 / covered by 幸祜 This song was from a detective ...

Last CF contest, I solved A~C really quickly, but got stuck for over an hour on a rerooting dp problem. In this blog, I want to learn how to do reroot dp! When to reroot dp? (Disclaimer: I will refer uuu as the parent node, and v,cv, cv,c as the child node) Reroot DP occurs when the problem wants a answer that would require making each node as the root of the tree. You should be able to calculate one of the answers in maybe O(n)O(n)O(n) time, and is able to transition subtree/outside subtree inf ...

Today, we did the ICPC North America Qualifier contest. It served as a in-school contest I would say. We only have two members for this contest, my other teammate was at GHC so she couldn’t do the contest. It was quite a stressful contest, especially we only have 2 people, but we still AK’d the contest and got 3rd place. We could’ve gotten 2nd place honestly, but FlamingLions solved the last problem right before the contest ended, and our penalty was too high so we got 3rd. As soon as the conte ...

While I was doing random 1700~2000 problem, I noticed one problem was the problem I did two years ago when I our club was choosing committee members. I was the only one that got full points in this problem! Now I revise this problem two years later, it was actually really easy. But 2021 yeedrag tried for nearly 3 days and dozens of attempts to get it accepted! The problem: 1486C2 Guessing the Greatest (hard version) Here is a comparison of the code for the same problem I wrote two years apart: 2 ...

Time flies! It’s already been one month since I came to the US. Things are going pretty smooth except that im too introverted to make friends in my dorm floor. But no worries! I still have a couple of friends and I plan to make more! Now lets give an update to various aspects of my life: Research This is one of the more unfortunate things. Skunkworks forgot to put me in the list in summer, and all researches were already full. I was pretty disappointed not gonna lie, but this also gave me a chan ...

Okay its actually already been almost 11 days since I got to the US, and like around a week since I moved in to my dorm. I’m starting to get used to the life here, and well I miss Taiwan very much. People here are all pretty friendly although a bit too chaotic haha. I currently live in Chadbourne resident hall, which is a pretty nice dorm with an awesome location! I can physically feel the temperature getting colder and colder each day, and it’s only september now! I wonder how cold it would go… ...

Well, I was todays year old when I found out you can’t register a contest 5 minutes beforehand… I guess I’ll vir it tomorrow then. I did two contest on 8/12, and they were both really interesting! ABC 314 Solve: 4/8 I haven’t done atcoder contests for a while now, and I honestly didn’t do as well as I expected. A to D were pretty standard atcoder problems, so I’ll skip them. E was a question about like probability expectation but weirdly, I still can’t understand the question even now. F was is ...

My PR was finally merged! This is my first time contributing to open source, so it’s really exciting for me :D The fix was for OpenMMlab’s MMsegmentation, which is a framework for AI segmentation tasks. We used it in our research im conducting now at Academia Sinica. I’ll write about it some day. Anyways, we were met with the problem of not being able to combine dice loss with other losses correctly, and after searching, alot of other people had the same problem as well! After some discussion, ...

I’m seriously considering whether I should try pursuing CP in college. I did CP in highschool before, and really didn’t achieve much. The main thing I should think about is what I can get from doing CP in college. I talked to Kuroma yesterday and I decided to give myself one year for CP: If I can’t get in ICPC or can’t get to atleast master in CF I’ll quit and focus on DL. I think this is a solid plan do really determine if I should spend my time on this, hope I can do it! I’ve also contacted a ...

Hello! .w. I went to the hair salon today to straighten and stick my hair to my head (idk what its called in English lmao). The chemical process was super itchy and I had to maintain the same posture for like 20 minutes, truely inhumane… Although after the process my hair did look pretty nice :D In the process, I was bored, so I mind solved a mashup of 1400 to 1700 CF problems. Suprisingly, I got them all correct after writing them at home! Im still worthy! The problems were all pretty nice so I ...

Hello again! You may be wondering why I said again? The reason is because I used to have another blog with the same domain, but I didn’t update it at all. So I basically redeployed a new blog in the event of me going to college (UW Madison), Horray! I mean, im really not good at documenting my life and stuff like that, because im often too lazy to get up and write stuff. I’ll try this time though (I promise although I said it last time lol) I tried to get pagination working, but I couldn’t find ...