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Google Tech Dev Guide

techdevguide.withgoogle.com

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Re: Google Tech Dev Guide

#31

Post by saulrh »

lwansbrough wrote: post #2

"Given a string S and a set of words D, find the longest word in D that is a subsequence of S." Found under "Foundations of programming" -- this is exactly the type of problem I'd expect as question one under this section. When it's made by Googlers, that is. I make a lot of cool stuff day to day, and usually that requires a lot of code and knowledge about programming and topics that are rather advanced (currently I'…

Funny, I use this kind of thing all the time when I'm programming. I wrote a comment citing the pigeonhole principal to justify a test case not thirty minutes ago. And I'm not even doing anything wizardly or revolutionary, just improving some concurrency code in a random worker binary.

As for your comment about "diversity of thought": These problems seem sterile when they're presented in the most general possible form with all the formal trappings. The subsequence problem is at the core of diff(1), for example, and it feels more interesting in some way to dig into that past reading and applying your diffs like usual. But if you try to present it as "it's diff(1)" you will only get people that already know what that means. "It's a simple spellchecker", "reassembling DNA", "disentangling two books that have been mixed together", etc, these specializations all introduce additional dependencies and restrict the availability of the lesson. Anyone can read "a string S and a set of words D". It may not be optimized for you, but who cares about what you think is boring or not? You already know this math. Personally, I gleefully soaked up everything my undergraduate algorithms classes offered, even the AVL trees and all that other random circles-on-a-whiteboard stuff, because I was learning something in its purest form. And if I needed more meat? Whatever I was learning from would have mentioned, as an aside, that it was also diff and DNA and spell-checking, and I could pick and choose from those as appropriate.

Finally, would you have reacted anything like this if the page had been spat out by your favorite Ruby super hacker wizard greybeard man? If it'd been an artisan webpage hand-crafted in the hipsterest coffee shop in oregon? If it's been on microsoft's recruiting page?

Re: Google Tech Dev Guide

#33

Post by gd2 »

Tried out cloud computing. Went to the first lesson, clicked the link for the YouTube of the first video class, described as "What is the Cloud? Watch this lively video for a quick overview of the Cloud landscape. Though it's a couple of years old, it's a great intro."

But got hit with a "this video is not available" YouTube page. A YouTube search for the same title brings up lots of possibles.

I'm hopeful about this.

Re: Google Tech Dev Guide

#35

Post by komali2 »

steve_musk wrote: post #21
lwansbrough wrote: post #14

Earlier quoted context omitted.

String matching, like == or string.compare? Anything more complicated than that and you're not building anything that isn't already available.

The point isn’t to build something new, but to learn CS foundations. Being able to think through this type of problem is absolutely worthwhile.

Why is it worthwhile?

Given finite time, a person could instead learn how to use a new established framework, API, or even programming language.

Re: Google Tech Dev Guide

#36

Post by m0zg »

akanet wrote: post #5
lwansbrough wrote: post #2

"Given a string S and a set of words D, find the longest word in D that is a subsequence of S." Found under "Foundations of programming" -- this is exactly the type of problem I'd expect as question one under this section. When it's made by Googlers, that is. I make a lot of cool stuff day to day, and usually that requires a lot of code and knowledge about programming and topics that are rather advanced (currently I'…

That's certainly your opinion, but the subsequence problem is a very general, abstract question that offers the candidate a number of ways to arrive a progressively better solution by following their intuitions. It's not the greatest interview question, but it's certainly not the worst. This website appears to be for people who already know how to code, and offers many different paths as well.

It doesn't. This seems like a typical Google interview question. If you didn't know how to solve it before the interview started, you aren't going to figure out anything other than a brute force solution in 45 minutes. And brute force solution will not get you a good grade in a tech interview at Google. It's idiotic: once you do get hired by Google, easily 80% of your work is copying one proto buffer into another, and the remaining 20% is mostly yak shaving and figuring out how things work in the absence of documentation. Dynamic programming should be the least of their concerns.

Re: Google Tech Dev Guide

#37

Post by myroon5 »

gd2 wrote: post #33

Tried out cloud computing. Went to the first lesson, clicked the link for the YouTube of the first video class, described as "What is the Cloud? Watch this lively video for a quick overview of the Cloud landscape. Though it's a couple of years old, it's a great intro." But got hit with a "this video is not available" YouTube page. A YouTube search for the same title brings up lots of possibles. I'm hopeful about this…

The link to https://priyankamandikal.github.io/posts/gsoc-2016-project-o... in 'Wikipedia accuracy review' also seems broken. Removing the trailing slash seems to fix it

Re: Google Tech Dev Guide

#38

Post by ascar »

lwansbrough wrote: post #2

"Given a string S and a set of words D, find the longest word in D that is a subsequence of S." Found under "Foundations of programming" -- this is exactly the type of problem I'd expect as question one under this section. When it's made by Googlers, that is. I make a lot of cool stuff day to day, and usually that requires a lot of code and knowledge about programming and topics that are rather advanced (currently I'…

I agree with you that a non significant number of developers need this kind of problem-solving ability for their daily work, but I would disagree that they never need it. And when they do it can have huge impact.

There are many applications of these fundamental problems in system building. They are usually not as obviously in your face as the coding interviews and it is often not possible to let a library do that stuff for you. That's why it's beneficial that every developer who might have to do this stuff, is capable of doing it.

E.g. it's a common problem to have a list of objects A and another list of objects B and you want to find all elements in B that match an element in A. The naive approach is thinking of 2 boxes with balls of different color. You pick one from the first box and compare him one by one with each ball from the second box. This is equivalent of nesting two loops and has a runtime complexity of O(n*m).

But this problem is absolutely solvable in O(n+m) with added memory of O(n) (or m, pick the shorter list), by creating a hashmap and then iterating once.

The difference in real world performance is huge. I optimized a small system dealing regulary with about 20mb of translation data from a 20 minute runtime to a few seconds. Not for a tech giant, but for a small webshop with about 100 employees.

Re: Google Tech Dev Guide

#39

Post by ascar »

m0zg wrote: post #36
akanet wrote: post #5

Earlier quoted context omitted.

That's certainly your opinion, but the subsequence problem is a very general, abstract question that offers the candidate a number of ways to arrive a progressively better solution by following their intuitions. It's not the greatest interview question, but it's certainly not the worst. This website appears to be for people who already know how to code, and offers many different paths as well.

It doesn't. This seems like a typical Google interview question. If you didn't know how to solve it before the interview started, you aren't going to figure out anything other than a brute force solution in 45 minutes. And brute force solution will not get you a good grade in a tech interview at Google. It's idiotic: once you do get hired by Google, easily 80% of your work is copying one proto buffer into another, an…

That's probably the issue with algorithm solving is not software engineering and if you mostly select on the first, you do not necessarily get good people in the second, broader and more important area. Then you end up with a terrible system to work with.

It's like hiring construction engineers only based on their performance in structural analysis. Sure, it's important that the house doesn't collapse, but this will not get it build.

Re: Google Tech Dev Guide

#40

Post by snaky »

m0zg wrote: post #36
akanet wrote: post #5

Earlier quoted context omitted.

That's certainly your opinion, but the subsequence problem is a very general, abstract question that offers the candidate a number of ways to arrive a progressively better solution by following their intuitions. It's not the greatest interview question, but it's certainly not the worst. This website appears to be for people who already know how to code, and offers many different paths as well.

It doesn't. This seems like a typical Google interview question. If you didn't know how to solve it before the interview started, you aren't going to figure out anything other than a brute force solution in 45 minutes. And brute force solution will not get you a good grade in a tech interview at Google. It's idiotic: once you do get hired by Google, easily 80% of your work is copying one proto buffer into another, an…

> figuring out how things work in the absence of documentation

That would be great interview test actually. Given a bunch of unknown code, add some simple functions, not breaking it apart. Keeping the style (not only syntactically) would be a bonus.

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