I would say CS 180 is definitely one of the most useful and interesting classes I've ever taken at UCLA. HOWEVER, as for the professor himself, I would say he's not helpful at all. I stopped going to lectures after like 2nd or 3rd week bc his lectures suck. And since he strictly followed the textbook I just decided to study the textbook myself instead of wasting time attending lectures(btw the textbook is great as it provides you an overall skeleton of how different algorithmic paradigms work, and gives you abundant examples showing how to apply those different algorithms).
The workload is chill. You only have around 5 hw problems every week. However, some of the problems can be really hard, even impossible to do on ur own. But anyways there are solutions available online and it seems that as long as you write something on each problem you'll get 100...
The midterm was hard with average around 40%. The final on the other hand was much better(at least compared with the midterm).

He is a nice professor. But the course itself is sooooo hard!!!! Not for undergraduate. I do not recommend.

Contrary to older reviews, Ostrovsky seems to have gotten better in terms of teaching. After a confusing beginning to class where he spent 2+ weeks talking about NP-completeness (a topic barely covered in other 180 lectures) as well as unclear lectures, he settled down quite a bit after week 4-ish and delivered lectures that are worth going to. This quarter, he decided to write on the blackboard instead of using slides, which has its pros and cons. A big pro is that he would talk slightly slower, but unfortunately he does not have the best handwriting, nor is he the clearest. Reading the textbook is essential in most cases.

Homework is definitely intended to challenge the students, but unfortunately most of them are basically un-doable without the solutions manual. That's not really a trait about his class though, as I hear this is the case with other professors too. (The textbook just has hard problems in general.) I'd still recommend doing them as much as possible on your own – and start early, as nothing beats the feeling of coming up with a solution yourself after thinking about it through over multiple days.

Exams are exponentially easier than the homework. Even so, this year the average for the midterm was in the 60s, though have actually gotten gradually easier over the past years. Most past midterms with Ostrovsky had averages in the 40s.

In general, not as horrible as other reviews make it out, but if you have the option of waiting one more quarter to get Sarrafzadeh, wait.

I am a junior and I have taken my fair share of UCLA CS classes. Out of all the professors I have taken, Rafil is the worst of them at teaching. Now let me list the pros and cons of this class to you and you can decide if you want to take it or not:

pros:
1. Professor Ostrovsky is very established in his field. He's also very patient to answer all the questions. He is also funny at times and know lots of stories of famous researchers
2. My TA Eli is amazing, best TA ever. He teaches much much better than the professor
3. As you can see on Bruinwalk, the curve is good
4. He gives out a compilation of his notes from 10 years ago so we can actually read the notes if we get confused from lectures. But surprise surprise sometimes his notes doesn’t agree with his lecture in terms of definition and implementations of things.
5. The material is pretty interesting if your into math and computer security

Cons:
1. The material is pretty hard. Pretty sure it used to be a graduate level class.
2. The professor is terrible at teaching. This lecture is definitely not a good learning experience for me . It looks like he doesn't prepare for the lectures at all and just write down everything from his mind to the (virtual) board, which, unfortunately could be full of mistakes at times, and then he has to rewrite everything several times and your screwed if you are taking notes. His lectures are extremely unorganized. He also likes abusing notations without informing us beforehand so everyone including the TAs get really confused. And then people will start asking him questions for clarification and then he would probably explain it using three times the time he used to explain the concept. He is so unclear that people have so many questions. The lecture could be so much more efficient if he explained everything clearly at the beginning. He also sometimes uses concepts we have never heard of without introducing them and then when people ask what it means he acts all surprised. Dude don’t you think you should probably spend 30 minutes to navigate the syllabus of prerequisites classes to understand what the students do and don’t know? Also, he is usually too lazy to talk about the general big picture of things and he is also too lazy to go to the detailed implementation of things so students are stuck in the middle confused about both what they are actually studying and how exactly does it work. In general, I feel that in order to do good in this class you have to already know everything before the lectures.
3. He gives no homework, so there is absolutely no way you can check if you actually understand the material. Then the exam are hard af and hes too lazy to make practice exams that he asks the TAs to make the practice exams and half of the actual exams.

Not the most exciting lecturer I've ever seen, but he's definitely a lot better than his reviews here suggest. I felt that he explained concepts pretty well, and he was pretty helpful when difficult concepts arose.

I learned nothing from his lectures. I have to self study by reading the textbook which thankfully is a saving grace at least for the midterm, but I just feel why would I take this class instead of just reading the textbook? His lecture slides have some errors, which for those who solely study the slides will not do so well unless they are smart enough or work hard enough to realize the mistakes.

Discussion sections do not really help at all. Most of the information I know is because I prepared leetcode problems over the summer, and because I am a junior, already am familiar with all types of problems. The grading for the exams seems to be arbitrary at best, where I either get full points or a big fat zero with obscure explanations as to why I lost those points. Asking for a regrade only yielded yet another obscure description without bumping my already abysmal exam scores.

The class itself depends way too heavily on the exams, which means if you are like me who perform somehow super badly on the exams, it is game over. By the way, I am in no way dumb, I am interning in the Big 4 this summer and know how to solve all these problems in the midterm and final, not to sound pretentious. I just lose almost all the points on the exam just because of obscure reasons even my friends do not know why, and I am just not a bright student academically.

At the first class, the professor look funny and he care about all students. He has no problem at all with regard to giving out PTEs. It turns out that you never need a PTE in that everybody drop the class or study by their own.

However, after a week, I was so so so disappointed. He is smart and intelligent and good in research. That's for sure. As a PhD student, I believe working with him to collaborate in a research must be a fantastic experience. But... the lecture (CS180), I'll probably say NO ... (soon).

It seems that he just use the slides from the publisher (how can you give a talk without preparing your own slide?). Somehow I disguise such a teaching style (reusing other's slides, especially when you use ALL of them and refuse to give it to students). YES! Everything you can find in TEXTBOOK. So why should I pay thousands of dollars to be here just for asking you to read TEXTBOOK out loudly?

I believe every instructor should put himself in student's shoes. I'm not here for listening your talk in a conference (if this is the case, he's okay despite of some accents). I "was" an instructor in a community college for several years before getting my PhD degree in UCLA, and I'm pretty confidence that his teaching style is very ineffective and irresponsible, at least, as a instructor in a "undergraduate" level class. Though, undoubtedly he is a great researcher and a wise, intelligent man. But in my opinion, no student would like such a teaching style.

Professor Ostrovsky is a great teacher! Though he can ramble off sometimes, I found that his passion for the subject really showed and it made me want to learn as well. Algorithms is a very interesting but difficult subject. He made it simple and easy to learn. And because he bases most of his lectures off of the textbook, you know exactly what to study. The midterm was really easy, requiring you to just think a little bit to apply the concepts you learned in class. All of the questions on the midterm/final were easier than the homework problems he assigned(about 4 a week). In general, great class as opposed to what other reviews on this site may say.

My experience with this class was a little unconventional, as I was taking a very heavy courseload and had less time to dedicate to it early on in the quarter. Still, I found that this class wasn't that bad, and you could skip classes and just read the textbook without missing a beat.

Homeworks are annoyingly difficult at times, but doable if you form a study group. However, homeworks only compose 15% of the grade, with 40% being the midterm and 45% being the final, so your final grade will be determined pretty much from those two.

My main issue with this course was the hike in difficulty between the midterm and the final. The midterm was generally easy, with an average score of 60% and std. dev. of about 10%. The final, however, was unbelievably harder in comparison. I studied for two days straight before the final, and a minimum of 3 hours a day starting 10 days before the final, and I had no idea how to approach a majority of the problems. I assume there will be a much lower average and std. dev. on this final, and given the midterm reflected the material better I'd say it's better to study for the midterm more than the final honestly.

Anyways, the course isn't that bad, and Ostrovsky may be the most competent professor to teach the class of all professors who do. However, from my experience, I urge those taking it to treat the midterm like a final, as it could prove extremely difficult to set yourself apart from the rest of the class on the actual final, even if you study a ton.

I think Ostrovsky is definitely getting better at teaching! This quarter he started writing out his lectures on the board instead of reading off of his slides (which is what I'm guessing he used to do based on previous reviews). This slowed down his pace a lot and made his lectures more interactive.
However, compared to other professors, he is still not the best lecturer. His handwriting on the board is almost illegible and a lot of the times he goes on tangents that are somewhat irrelevant to the class. He's really good at explaining things but it's really hard to survive this class without reading the book because the notes that he writes on the board aren't really "notes"...they're more like pictures/diagrams to help explain what he is saying. He rarely provides concrete definitions for mathematical terms/algorithms, and given the fact that this course is a very theory-intensive course, it's difficult to solely rely on his lectures to study.
For me, I just stopped taking notes after the 1st or 2nd week and tried my best to listen to what he was saying in class. I just read the chapters beforehand and his lectures made a lot more sense. Just read the book and you'll do fine.