quicksort is O(n^2) which is definitely not the "best big-O" for sorting.
"how do you count the bits most efficiently?" What does this even mean?
What i think he means is counting the amount of set(1) bits in the array,
Google's “Director of Engineering” Hiring Test
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Re: Google's “Director of Engineering” Hiring Test
#112quicksort is O(n^2) which is definitely not the "best big-O" for sorting.
"how do you count the bits most efficiently?" What does this even mean?
If you have a collection of data, and you want to know the number of 1 bits, and you want to do it with a minimum of resources... what is the process?
For example, standard bit-shifting and masking the lowest bit to set a counter is one way to do this. Possibly there are other, faster ways, such as using a lookup table (a byte or more can be "counted" at a time). Of course, because so many people were doing this, intel added a popcnt instruction which probably is more efficient (faster) than either of the above, at the expense of more CPU real estate, heat, etc.
Turns out counting 1 bits in a dataset is a super-important problem that shows up in a lot of situations.
Re: Google's “Director of Engineering” Hiring Test
#113Wow, I had almost the very same set of questions for a junior SRE role! The difference is: I graduated ~1 year ago and therefore have a lot less experience than this guy.
It was kinda funny, the recruiter called me to "go through some of the questions to see what I will encounter in the actual interview". I remember, when asked about what Unix function accepts connections on a socket I could just answer "dunno", because I never used or did that. Even more funny if you consider that they actually came across my profile and called me initially and there is just no place in my CV where I claim such "low-level" knowledge. I also remember that Inode question, "What is stored in an Inode?" - Again "idk" and the answer the recruiter gave was "metadata". Yes of course metadata, goddammit, what else? (Can an answer really be that simple???)
After the interview I felt quite devastated because I did not expect that I had to come up with a solution to process an array with the size of 10,000 in a call with the recruiter. I wasn't (and I'm still not) sure if this was only preparation or an actual interview. In the latter case, I was sure that I failed. Surprisingly however, I was invited to an actual engineering interview some time later.
Re: Google's “Director of Engineering” Hiring Test
#114I've been at Google for five years as a SWE and I've been interviewing for 3 of those. I'd fail this pop quiz. This strikes me as bizarre and inconsistent with all the practices I'm aware of. The idea that we'd ask anyone this stuff, let alone director candidates, strains belief.
I only have a sample size of one, but I blew threw a phone interview with Google about a year ago -- and the guy giving it was very technically skilled. We talked about the subtler aspects of the questions as we went. They offered an in-person interview, of course, but I declined when I found out that they were only hiring for Google Payments in Boulder. I'm sure the job has interesting aspects, and maybe my imaginat…
Wait. You didn't know what position and location you were being interviewed for? That kind of arrogance from a company can only exist if the job seekers are desperate or perceive any job at Google as nirvana.
Re: Google's “Director of Engineering” Hiring Test
#115Earlier quoted context omitted.
I knew all these answers too, because I was a developer in the 1990s. There is absolutely no purpose to knowing off the top of your head how long an ethernet address is, or even what system call will retrieve an inode (his bickering over stat() "filling in" rather than "returning" was bogus, for what it's worth). The top Google search result for each of these questions has the answer. Knowing these things isn't part…
The question was what function "returns" an inode. Those functions return a error code, you pass in a stat structure and the function populates that structure. He was saying (correctly), that they don't return (in the classic C sense) the inode. They return an error code. To me that is a big difference... int lstat(const char path, struct stat buf); vs stat* lstat(const char *path); 2 completely different functions.
This strikes me as an entirely trivial point, the meaning of the question was pretty clear. It wasn't "what is the literal return value". Many APIs will return error codes, and people still talk about them as "returning" certain values colloquially. Of course, if the OP's answer would've been "it returns an error code :) but I assume you're talking about..." I would think that's fine.
Btw, that is the only thing I really disagreed with OP on, the rest seemed just ridiculous.
Re: Google's “Director of Engineering” Hiring Test
#116Re: Google's “Director of Engineering” Hiring Test
#117I'm amazed he knew things in such detail. I mean who would know just how long a MAC address is? Or what the actual SYN/ACK etc tcp flags are? You just need to know what they're used for, and if you need the specifics, you'll find out with a single search. He seemed to know that as well though. Kernighan for bit twiddling algos, that kind of thing. It's a bit strange to have someone non-technical interviewing a techie…
Medical Recruiter: "What are mitochondria?" Applicant Doctor: "They're double membrane-bound organelles found in all eukaryotic organisms, commonly between 0.75 and 3μm in diameter, that generate most of the cell's supply of adenosine triphosphate" Recruiter: "No. They are the powerhouse of the cell".
What are the components that make up a color?
"Well, it depends what color model you are using, which differentiates between additive and subtractive color mixing, the medium used (print, screen, etc.)...
No. It's Red, Green, and Blue.
Re: Google's “Director of Engineering” Hiring Test
#118Earlier quoted context omitted.
I knew all these answers too, because I was a developer in the 1990s. There is absolutely no purpose to knowing off the top of your head how long an ethernet address is, or even what system call will retrieve an inode (his bickering over stat() "filling in" rather than "returning" was bogus, for what it's worth). The top Google search result for each of these questions has the answer. Knowing these things isn't part…
But what if Google is down and you are tasked with diagnosing it?
Ask Jeeves? Being able to find it in a book might be useful, but when Google is down I bet they would like to get things up and running as soon as possible.
Re: Google's “Director of Engineering” Hiring Test
#119Ha ha re: > 10. what is the type of the packets exchanged to establish a TCP connection? > Me: in hexadecimal: 0x02, 0x12, 0x10 – literally "synchronize" and "acknowledge". > Recruiter: wrong, it's SYN, SYN-ACK and ACK; if Google is down you will need to know this to diagnose what the problem is. We will stop here because it's obvious that you don't have the necessary skills to write or review network applications. Y…
Surprising they wouldn't have given the recruiter a list of alternate acceptable answers. Almost feels like the recruiter was conspiring against you, but why?
Why the hell is a non-technical recruiter giving these tests? Google engineers or managers should be administering it, not the high school dropouts who make up the recruiting industry. There's so much wiggle room here that have a rote-memorization style test for engineering is completely crazy. I've never had a technical test given to me by a recruiting firm. Its always a call with someone from the company, if not the hiring manager.
Perhaps this is what they give to 'second string' applications to make HR happy while the guys who actually get the jobs are friends of the hiring manager or team leads. Or its a H1B ploy to say, "See Obama, we need tech talent. Look how terrible our domestic talent is. They score 40% on our tests!" Meanwhile Bombay Upstairs University has a wink-wink-nudge-nudge deal with Google hiring managers who accidentally leak the test on a 'forgotten' ftp site.
Everything about this is fishy. I think there's fraud here, not just incompetence. I've been the hiring stooge for shops who have already made their decisions before and its always terrible and, frankly, hurtful. These are the signs of a non-serious 'stooge' interview.
Re: Google's “Director of Engineering” Hiring Test
#120I'm amazed he knew things in such detail. I mean who would know just how long a MAC address is? Or what the actual SYN/ACK etc tcp flags are? You just need to know what they're used for, and if you need the specifics, you'll find out with a single search. He seemed to know that as well though. Kernighan for bit twiddling algos, that kind of thing. It's a bit strange to have someone non-technical interviewing a techie…
Medical Recruiter: "What are mitochondria?" Applicant Doctor: "They're double membrane-bound organelles found in all eukaryotic organisms, commonly between 0.75 and 3μm in diameter, that generate most of the cell's supply of adenosine triphosphate" Recruiter: "No. They are the powerhouse of the cell".
To be entirely objective, I have run into recruiters of that variety in my career. However I've also had plenty of recruiters that were able to pick up on one's deeper knowledge of a given concept and accept that as correct, even if it wasn't the "textbook answer" they were looking for.