Big O Notation – Using not-boring math to measure code’s efficiency • Hacker News Board

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#31

Post by spraak » Fri, Aug 02, 2019, 3:52 AM UTC

dntrkv wrote: post #18

abalone wrote: post #13

I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream. There's a common narrative too, that it's all about algorithm question prep and it's a "game" you can win. One youtuber who recently landed a ~$275K TC gig said it's not about being "intelligent" it's about pr…

It depends on the company, but most of the FAANG company (and others that try to imitate them) interviews come down to how quickly you can get the optimal solution on the board. It has very little to do with how well you can code day to day. Most interviews have 4 sessions broken up in the following manner: 1 hour: coding 1 hour: coding 1 hour: lunch 1 hour: system design 1 hour: cross-functional In my experience tho…

I wish the usage of FAANG would die. Firstly it exlcudes obvious others like Uber, Microsoft, etc. Secondly, and purely aesthetically, it sounds silly. I hereby propose we call such companies the Big N, and I'm definitely open to other ideas.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#32

Post by devnulloverflow » Fri, Aug 02, 2019, 3:53 AM UTC

ajmarcic wrote: post #12

This article misses an actual definition of Big O. This forces us to skip crucial points like why O(n^2) truly identically equals O(n^2/2 + 5n). The author instead seems to think they are approximately the same because the lower order terms are small compared to the highest one. We only need to explain the definition and the reader could understand why an O(n) algorithm is in O(n^2), why some O(n^3) algorithms are mu…

> The author instead seems to think they are approximately the same because the lower order terms are small compared to the highest one.

In fairness, this is actually why we care in practice about asymptotic issues. The fact that there is a rigorous mathematical viewpoint that makes them strictly comparable is helpful for being confident about the non-trivial results -- but the reason we care about it is because we want to know roughly how expensive our code is (or will be).

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#33

Post by abalone » Fri, Aug 02, 2019, 3:57 AM UTC

mevile wrote: post #25

dntrkv wrote: post #18

Earlier quoted context omitted.

It depends on the company, but most of the FAANG company (and others that try to imitate them) interviews come down to how quickly you can get the optimal solution on the board. It has very little to do with how well you can code day to day. Most interviews have 4 sessions broken up in the following manner: 1 hour: coding 1 hour: coding 1 hour: lunch 1 hour: system design 1 hour: cross-functional In my experience tho…

Where I work we give people real problems to solve during interviews. We have a great team that gets a lot of work done. In hiring we put emphasis on practical expertise with the tech we use and the problems we face and not academic puzzles. There's immense value in having a strong computer science background and I feel we've had success being able to get a sense in our candidates where they stand without the standar…

Can you give an example problem?

I wonder how rigorous non-algo challenges can be inside of an hour. Or how you would “get a sense” of CS fundamentals without algo tests.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#34

Post by abalone » Fri, Aug 02, 2019, 4:01 AM UTC

halfnibble wrote: post #23

save_ferris wrote: post #15

Earlier quoted context omitted.

A major force driving this is the employers who choose to conduct interviews in this way. I'm a developer with about 6 years experience in full stack web app development (Rails & Django mostly), and I recently got my ass absolutely kicked during a couple of live coding challenges that were very heavy on theory (also worth mentioning that I'm a self-taught dev without a CS degree). I started talking to some former cow…

Self-taught as well. It’s a game. All the big name software co’s and the startups founded by former big name software devs like to play it. Heck, I’m starting to enjoy the game (primarily because I have exceptional pattern recognition skills). I was failing interviews too until I picked up an undergrad CS algorithms book and read through the first few chapters on data structures and theory. Then I signed up for LeetC…

Maybe you should start a coding interview prep course...

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#35

Post by hello_moto » Fri, Aug 02, 2019, 4:44 AM UTC

abalone wrote: post #13

I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream. There's a common narrative too, that it's all about algorithm question prep and it's a "game" you can win. One youtuber who recently landed a ~$275K TC gig said it's not about being "intelligent" it's about pr…

> I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream.

It's akin to the Fitness world. There are tons of people selling proteins whey, their fitness apps, fitness set "reps", etc. Can't blame them, they're selling what people want.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#36

Post by eridius » Fri, Aug 02, 2019, 4:45 AM UTC

dntrkv wrote: post #18

abalone wrote: post #13

I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream. There's a common narrative too, that it's all about algorithm question prep and it's a "game" you can win. One youtuber who recently landed a ~$275K TC gig said it's not about being "intelligent" it's about pr…

It depends on the company, but most of the FAANG company (and others that try to imitate them) interviews come down to how quickly you can get the optimal solution on the board. It has very little to do with how well you can code day to day. Most interviews have 4 sessions broken up in the following manner: 1 hour: coding 1 hour: coding 1 hour: lunch 1 hour: system design 1 hour: cross-functional In my experience tho…

I wish people would stop quoting that tweet. mxcl doesn't know how to work at a big company. He failed miserably at Apple as a result, and he would have done equally as badly at Google. The success of Homebrew has more to do with product fit than actual technical ability.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#37

Post by hello_moto » Fri, Aug 02, 2019, 4:52 AM UTC

dntrkv wrote: post #18

abalone wrote: post #13

I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream. There's a common narrative too, that it's all about algorithm question prep and it's a "game" you can win. One youtuber who recently landed a ~$275K TC gig said it's not about being "intelligent" it's about pr…

It depends on the company, but most of the FAANG company (and others that try to imitate them) interviews come down to how quickly you can get the optimal solution on the board. It has very little to do with how well you can code day to day. Most interviews have 4 sessions broken up in the following manner: 1 hour: coding 1 hour: coding 1 hour: lunch 1 hour: system design 1 hour: cross-functional In my experience tho…

> The other funny thing is that your previous experience doesn't do anything for you other than maybe getting to skip the technical phone screen. Everyone goes through the same process

You could also argue that this is fair chance between those who just came to the field.

> On the bright side, it does look like many companies are now realizing this isn't a great way to evaluate someone's ability and are beginning to incorporate more practical exercises.

It's the other way around: many more companies are incorporating Leetcode style interviews as their first "filters" either via online test or quick on-site.

Here's what happened: it used to be the case that only these FAANG companies have the resources and the know-how to either create these "trick" questions or picked a few from their favourite Algorithms book "exercise" part.

These days thanks to many "algo" challenge websites (like InterviewCake.com) that not only provides questions but also correct, detailed, and optimized answers, it is getting easier for employers to just pick a random ones and use that as interview materials.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#38

Post by hello_moto » Fri, Aug 02, 2019, 4:54 AM UTC

abalone wrote: post #21

save_ferris wrote: post #15

Earlier quoted context omitted.

A major force driving this is the employers who choose to conduct interviews in this way. I'm a developer with about 6 years experience in full stack web app development (Rails & Django mostly), and I recently got my ass absolutely kicked during a couple of live coding challenges that were very heavy on theory (also worth mentioning that I'm a self-taught dev without a CS degree). I started talking to some former cow…

To be clear I think it’s good to test CS fundamentals even if you don’t use them every day. It’s a good screen for aptitude. I’m just concerned that taken to the extreme it mistakes excessive pattern recognition prep for true comprehension and aptitude. Especially if it’s “whoever puts the optimal solution on the board fastest wins.” I do think it would do you some good to read up on core CS and algorithms though. I…

> I’m just concerned that taken to the extreme it mistakes excessive pattern recognition prep for true comprehension and aptitude. Especially if it’s “whoever puts the optimal solution on the board fastest wins.”

I agree with you on this. They do have taken this to the extreme because the questions are getting harder and harder.

This is hard tbh because if you're an employer whom used to be able to filter candidates by asking "easy" algorithms questions and woke up one day to only find out that everybody knows the answer, what will you do?

"It used to work so we just have to improve it, right?" => make a more challenging questions.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#39

Post by edejong » Fri, Aug 02, 2019, 5:01 AM UTC

User23 wrote: post #22

RodgerTheGreat wrote: post #5

Earlier quoted context omitted.

For a completely arbitrary program, it is not possible to calculate a tight bound on the time or memory complexity of that that program via static analysis. See Rice's Theorem[0]. It is possible to determine interesting properties of programs if you weaken your requirements to approximations and/or add significant constraints. You can maintain properties by construction if you only allow yourself to use certain kinds…

> For a completely arbitrary program, it is not possible to calculate a tight bound on the time or memory complexity of that that program via static analysis. See Rice's Theorem[0]. That theorem proves that no general algorithm exists. That doesn’t mean it can’t be done for a particular program. The real challenge is that modern compilers and processors will execute in a way that is hard to predict from source code.

The question was whether it is hard to determine the space/time complexity of ‘a’ function, which firmly placed the question in Rice’s theorem grounds.

Re: Big O Notation – Using not-boring math to measure code’s efficiency

#40

Post by ma2rten » Fri, Aug 02, 2019, 5:03 AM UTC

abalone wrote: post #13

I've noticed there are SO many of these "coding interview prep" courses lately. Like, obviously it's a hot job market, but there's just so many and of a certain vibe that it seems like some are selling a dream. There's a common narrative too, that it's all about algorithm question prep and it's a "game" you can win. One youtuber who recently landed a ~$275K TC gig said it's not about being "intelligent" it's about pr…

I work at Google. I think it's half true.

I would not have passed the Google interview if I had not prepared. After 3 years, I have completely forgotten most of the prep. I couldn't even implement a binary search right now.

That said, I do have an innate ability for problem solving. I know another person, who has prepared significantly more than me (multiple months full-time) but still wasn't able to get an on-site interview. In my opinion, it requires at least a minimum level of intelligence, luck and preparation.