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

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

#21

Post by abalone »

save_ferris wrote: post #15
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…

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 also did not get a CS degree and learned in the field, but now having studied up on it I feel much more in command of my craft. They do come into play now and then, it’s not just brain teasers. It does take weeks to months to really learn it though so I understand the resistance.

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

#22

Post by User23 »

RodgerTheGreat wrote: post #5
smudgymcscmudge wrote: post #2

I have a question for those with a better understanding of such things. Is it difficult to calculate time or memory complexity of a function through static analysis? It seems kind of basic, but I still find myself manually checking code instead of relying on a tool.

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.

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

#23

Post by halfnibble »

save_ferris wrote: post #15
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…

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 LeetCode premium. After a couple months of reading and practicing, I was getting an offer from every place I interviewed at. Now I’m at one of those big name software companies, and if I’m ever asked to interview a candidate—well, I don’t know what I’ll do. Maybe something with a binary search tree. I’ve literally never had to use that in 8 years of development. :)

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

#24

Post by mancerayder »

save_ferris wrote: post #15
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…

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…

As a DevOps guy who's been screened out of companies that care about such things, I'm a mix of horrified and skeptical.

I'm horrified because I'm seeing some gross incompetence in the realm of organization in thinking, clean infrastructure and security awareness. And some of this punishes the old(er).

I'm skeptical because I think many of these interviewers are themselves lousy systems people, are building environments that may need to be bailed out one day, and to boot are probably not people persons. A people person can sense better how to conduct an interview to feel out how to determine whether the candidate is clever and useful.

I took a managerial route so I'm mostly immune now, but boy do those cocky coding interviews stick in my craw when I think about them.

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

#25

Post by mevile »

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…

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 standard whiteboard hell other companies put their candidates through.

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

#26

Post by [deleted] »

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…

[deleted]

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

#27

Post by jrumbut »

curiousgal wrote: post #9

> not-boring math What's next? Gradient decent with no gradients? Fourrier transform with no functions? If math is do boring just skip the whole thing, don't try to kid yourself by saying you're not doing it when you are in fact doing it. /rant

I was really hoping that this was going to be some lively new way of thinking about or teaching big O notation, "Eulerian path runtime grows like the velocity of a car that drove off a cliff but Hamiltonian path runtime grows like the number of plague bacteria in a petry dish."

I was disappointed.

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

#28

Post by dntrkv »

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…

A strong CS foundation is hugely valuable and I don't think anyone will argue that but the fact that someone with over a decade of experience can go from a "no hire" to "hire" after a couple months of practice tells me that we aren't testing for the right skills.

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

#29

Post by abalone »

dntrkv wrote: post #28
abalone wrote: post #21

Earlier quoted context omitted.

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…

A strong CS foundation is hugely valuable and I don't think anyone will argue that but the fact that someone with over a decade of experience can go from a "no hire" to "hire" after a couple months of practice tells me that we aren't testing for the right skills.

Being exactly of those people (experienced but would have failed algo screen and had to brush up), I can confirm it would have false negatived me despite years of competent productivity... and yet I also feel I have filled in some significant gaps that I was lucky to avoid previously.

I think if you have a really strong “portfolio” of individual work that can be validated as being yours, like side projects, that can be a valid pathway into at least non senior roles. Maybe you’re weak on algos and other team members can help out at key points.

But I don’t know a better objective and direct measure of coding aptitude inside of 60 minutes. My issue is not with it in principle, at least for senior roles. It’s taking it to an extreme and misinterpreting the results. It gives this false sense of certainty about aptitude.

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