leetcode seems to agree with your definition [0]. the meme isn't to say that inverting a binary tree is particularly difficult - anyone familiar with coding challenges and trees could trivially produce a solution. the meme is more pointing out how ludicrous it is that senior/staff/principal interviews can hinge on these types of problems, despite the engineer proving their proficiency by doing something like running DOOM in typescript types or writing homebrew [1]. [0] leetcode.com/problems/invert-binary-tre…... [1] x.com/mxcl/status/608682016205344768

At least Max Howell (Homebrew) got an interview before getting rejected: x.com/mxcl/status/608682016205344768?la… In all seriousness though, the situation sucks. But there's still upside. Someone might reach out.

Spot on critical analysis of the blog post "Developers reinvented" by Github Thomas Dohmke which includes such quotes as: > Many Computer Science (CS) programs still center around problems that AI can now solve competently. Yeah. No they do not. Competent CS programs focus on fundamentals not your ability to invert a binary tree on a whiteboard. [1] Replacing linear algebra and discrete mathematics with courses called "Baby's First LLM" and "Prompt Engineering for Hipster Doofuses" is as vapid as proposing that CS should include an entire course on how to use git. [1] x.com/mxcl/status/608682016205344768

> ...that Google hires puzzle solvers over technical talent is just not true. Yeah, they do: twitter.com/mxcl/status/608682016205344…

This is really interesting to look at in the context of other hiring testing -- like Google's practice of asking silly abstract questions like "invert a binary tree" for jobs which do not involve substantial algorithmic work. eg: twitter.com/mxcl/status/608682016205344…

Still love this tweet: twitter.com/mxcl/status/608682016205344…

This is one of my favourite tweets: twitter.com/mxcl/status/608682016205344… I've seen some rather complex problems being asked in interviews. I've always wondered why my credentials don't seem to matter when it comes to programming skills. I have a masters degree where i did some very tricky algorithms and I even open-sourced it for all to see. But every time I've been looking for a job, i have to rehearse some leetcode problems so that i can put on a good show for 45 minutes. I get that deep-dives matter a lot and i can respect some of those exercises. These are crucial for senior positions since ideas are more important than code. Then I really get the life story kind of interviews because relating to coworkers and culture fit are hugely important. It's just the dang leetcode that ticks us all off isn't it?

Heaven forbid a FAANG doesn’t touch your code. Look at all the exposure you’ll miss out on. They might actually have to spend resources to write and maintain the code themselves, instead of open source maintainers begging for scraps [1]. The horror. The homebrew maintainer couldn’t even get hired at Google [2] if I recall, even though they’re big fans of using the tooling internally! [1] arstechnica.com/information-technology…... (OpenSSL Software Foundation President Steve Marquess wrote in a blog post last week that OpenSSL typically receives about $2,000 in donations a year and has just one employee who works full time on the open source code.) [2] twitter.com/mxcl/status/608682016205344… (Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.)

twitter.com/mxcl/status/608682016205344… Rigid interviewing techniques like that can easily weed out great candidates. Your confidence in your own process leads me to believe you may have missed a few great ones yourself.

I think usually people who try to make this point are just pouting over how they shouldn't be expected to know basic, fundamental things. Like twitter.com/mxcl/status/608682016205344…

Hah! Reminds me of twitter.com/mxcl/status/608682016205344…. Cynical answer though — Google does not want people like you. They don't want to hire entrepreneurs or inventors. They want people who can churn out code when given specific instructions, and that is what their interview process optimizes for.

I second. Most data and anecdata says you need to be a solid generalist software engineer to be hired at Google. You may have some specialty (the vast majority don't), but a single area of expertise won't take you there. Vide the famous tweet (twitter.com/mxcl/status/608682016205344…): "Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off." To be clear, I think that Google has a reason for that: - They use standardized hiring procedure (they need to work at a scale). - A startup/software/machine learning whizz kind won't be useful (or would be dangerous) if they contributed code that does not meet other software enginering criteria.

A great example of this is a tweet from Max Howell (creator of Homebrew) regarding interviewing at Google. Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

Reminds me of: twitter.com/mxcl/status/608682016205344… How exactly could a PM interview process (which is just asking you to walk through a bunch of design scenarios) give a stronger hiring signal than having developed a product the company wanted to acqui-hire? Honestly somewhat insulting that they made him go through a full external interview loop. At most it should have been some informal chats of the sort you get when transferring teams internally.

> why can’t I get a $300k/year job without knowing what a trie is You're grossly misrepresenting my complaint. I've made contributions to several high-profile OSS projects (including some small HTTP core contributions to Golang), have published one book as a co-author (another as an editor; both with Apress), have several projects with 100+ stars on GitHub, and am in the top .9% of Stack Overflow contributors. This is in addition to having a few interviews out there given to legitimate outlets, like Vice and PCGamer, about past startups (all of which have involved hardware or software). My pedigree is verifiable. And yet, if I want to switch jobs (which I will inevitably have to do), I will be subject to being asked about some algorithmic questions that I am willing to guarantee I couldn't answer without studying. For example, I genuinely don't remember how red-black tree or splay tree balancing works. But I'm small fries compared to people like Max Howell[1] (who wrote and manages brew) and yet couldn't get a job at Google because of some algorithmic question he flunked. Fighting for better interviewing practices in software engineering is one of the few hills I'm willing to die on. [1] twitter.com/mxcl/status/608682016205344…

This is equally interesting (or equally bad): "Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off" [0] More details two years later here [1]. [0]: twitter.com/mxcl/status/608682016205344… [1]: quora.com/Whats-the-logic-behind-Google…...

Agree with everything the OP said but I'd add: when hiring for senior engineers, this process is even more absurd because the real skill of senior engineers is not how much horizontal knowledge they've acquired (knowing web frameworks, Linux guts, databases, distributed systems, etc) or vertical knowledge (being a domain expert in X) but their soft skills -- how good are they at convincing other people of something in a meeting? A real example: a product person once asked a team I was on for a feature that'd be difficult and time-consuming to program, probably taking the better part of a year. My teammates said no. Not, "We want to ship this software soon and we don't think that's an acceptable tradeoff," they just said no. Product became furious (not knowing how hard it'd be, since the engineers hadn't explained it) and it hurt those developers. Knowing how to invert a b-tree doesn't help you solve situations like those, which are far more common than 99% of fake problems presented in programming interviews. When I interview a candidate I ask them to tell me about projects they worked on and poke and prod about real-world stuff they actually did, not converting a singly linked list into a circular linked list. Ideally people would be offered the choice of an in-person or take-home to satisfy both those who feel like they shouldn't have to spend their free time on homework and those who don't like being forced to instantly come up with solutions to fake problems. I blame Google for introducing this scourge, hopefully it lifts before the next time I do a job search. My favorite example of this is Google turning down Max Howell for a job: twitter.com/mxcl/status/608682016205344…

Welcome to the wonderful world of interviewing in tech! And people wonder why most software is shit. twitter.com/mxcl/status/608682016205344…

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 though, the first two are the ones that really make or break candidates, if you don't pass both, you're not getting hired. And yes, most of those interviews just test your knowledge of how quickly you can figure out the right data structure and algo for the question at hand. And even if you know all of the data structures and the applications of each, it can be incredibly difficult to solve the problems in the allotted time. 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. e.g. twitter.com/mxcl/status/608682016205344… 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.

Unfortunately, that's not how big company recruitment processes work: twitter.com/mxcl/status/608682016205344…

The reference point for gaining employment is that dude who wrote Homebrew and got rejected by Google for being unable to "invert a binary tree on a whiteboard" [1] Unfortunately with this and many other articles I've read on HN over the years, the common theme is that decent/good programmers are not making it past HR. Everyone that wants to work in tech should instead navigate through the meetup/social space and build up a decent network for this kind of thing. Anecdotally, at 1 interview I went for, I knew the hiring manager and our "interview" was a 15 minute casual chat. That's it. [1] twitter.com/mxcl/status/608682016205344…

In the past I've given programming tasks that mimic real life work as closely as possible and fit them into a reasonable time frame - for example, 1 hour of pairing/programming during an arranged face to face interview. If the test is well designed, touches on a number of areas and self contained, I think this was sufficient for me to assess their skills. "Mimic real life" means no puzzles (unless I've literally experienced them in real life), no binary tree reversals and no big O notation questions. >You have just dismissed most tech companies. All the large ones (Google, Apple, Amazon, Microsoft, etc.) give coding puzzles as part of their interview process. I think that type of thinking leads to embarrassments like this: twitter.com/mxcl/status/608682016205344… I think he experienced exactly the same problem the OP is talking about and in this case it's not him who was dumb, it was Google. I wouldn't rule out any of those companies but I think I'd rule out joining through the standard interview process - I'd look for specific people who looked to be doing exciting work on specific teams and try to befriend them. >you'd be wrong to say they have an entitlement complex or aren't the smartest. I think it would depend upon the team. I think they're not all geniuses, and they do have a tendency to drink their own kool aid. For sure some teams are great though.

At top companies, there's very little chance you are getting through without being convincingly good at CS heavy topics (DataStructures, efficient algorithms, etc.) Case in point: twitter.com/mxcl/status/608682016205344…

seconding this, creating value is orthogonal to knowing CS. see the creator of homebrew, Max Howell infamously failing to invert a binary tree in an interview: mobile.twitter.com/mxcl/status/60868201…...

Well, I hope so - the author of Homebrew ended up having trouble finding employment: twitter.com/mxcl/status/608682016205344…. Stranger things have happened.

The definitive example: twitter.com/mxcl/status/608682016205344…

I believe it's in reaction to the malpractice of hiring programmers according to their results on a purely theoretical exam at the whiteboard, and sometimes disregarding completely their precedent works, published projects, etc. I'm sure there are other examples predating it, but the following I believe is the 1st account of a Google interview gone bad for someone who very likely didn't deserve to get kicked in the butt (Max Howell, author of Homebrew for MacOS). twitter.com/mxcl/status/608682016205344…

I know this is a super-unpopular opinion these days, but... Why can't you program the simple problems that interviewers use for whiteboard coding without Stack Overflow? It's not even like interviewers are looking for syntax-perfect code (which you wouldn't need Stack Overflow for anyway, the compiler is what catches that for you). I've never had an interviewer that would quibble over a missed semi-colon here or there. Hell, most of the time I end up using "begin/end" style pseudo-code instead of curly-braces, because curly-braces are stupidly hard to draw well on a whiteboard. And even if you don't know off the top of your head what "invert binary tree" means, every interviewer I've ever had has been more than willing to answer any questions I have about the problem. Ask questions about requirements and you should be able to figure it out. If, once you know what the inputs and outputs of "invert binary tree" should be and you still can't do it, I seriously gotta question what the hell you're doing interviewing for the job of programmer. I once passed an interview for a job I wasn't even applying for, even though I didn't know off the top of my head what "LRU cache" meant, by asking enough questions ("oh, LRU means least-recently used? Well then, something like this?") I tend to think of whiteboard coding problems as being ineffective for interviewing because the problems are so simple. To me, anybody should be able to solve these problems. I know a lot of people can't, and this serves as a quick filter to winnow them out. But they are so ludicrously easy I just don't get how you can say you need Stack Overflow to solve these problems. I'm with Jonathan Blow on this one: twitter.com/mxcl/status/608682016205344…

I have a CS degree from a first-tier school. My experience with exams and interviews is almost the exact opposite of yours. In exams I don't get as nervous because I know that if I know the material then I will pass, if I don't then I won't. You can't bullshit your way past the professor/TA grading your exam. But in interviews I know that people who are far better than me have failed[0], and that people less competent than me could get the job. So it's not my coding ability or my experience that's being measured here, it's something else. And I don't know whether I have that something else or not. Maybe I do, maybe I just don't. [0] twitter.com/mxcl/status/608682016205344…

> I've never gotten this feedback from anyone I would consider competent. You may not have gotten it personally, but some very smart people have given precisely that feedback regarding those sorts of questions. twitter.com/mxcl/status/608682016205344…

Not true. I've got a Ph.D. in theoretical physics, am very math heavy, created a number of algos for my work over the last 25+ years (in physics sim, bioinformatics, systems management/orchestration, etc.), run sessions at an ACM conference, yadda yadda yadda. Two google interviews, and nothing. From what I hear from other people I consider way smarter than I, they also got nothing. Google has a much copied process, but as a creator of something of huge value notes: twitter.com/mxcl/status/608682016205344… Mebbe their filter isn't quite as good as they think it is. Talking to a number of absolutely brilliant engineers who didn't get hired, it likely has nothing whatsoever to do with talent, algo knowledge, mathematics, etc. There are other factors. Being an above 40 guy probably didn't help me, google and others seem to have lots of trouble with ageism. Dan's article was not specifically about being the "top", rather, what does the "top" mean in context, and how do people judge. What is the opportunity cost of doing this? As he points out, as I point out, it can be very high. The smartest programmer I met in my first decade of work, was a person who had a high school diploma. No college degree. The guy was brilliant, personable, humble. He is quite successful now, and still doesn't have degrees. Chances are, he doesn't have formal education around the math/algos, but has picked up everything he knows. At the end of the day, hiring is something of a crap-shoot. Past performance is not a guarantee of future performance, either negative or positive. You are after passion, intelligence, fit, experience if it exists (re-inventing wheels can be time consuming/expensive if you are forced to do it, and getting a guide who has been down that path can save you making some mistakes/time/money). I know people are telling themselves that google has a good process, but honestly, it looks like it enforces homogeneity more than it brings in needed talent. I am not sure this is a good thing. Poor replication of their processes is rampant throughout the industry. I am not convinced this leads to positive outcomes.

The maintainer's tweet about interviewing at Google is one of my favorites: mobile.twitter.com/mxcl/status/60868201…...

In an industry with extreme growth like tech has seen in recent decades, it's easy to imagine that many successful companies are successful just as much in spite of their interviews as they are because of them. An example: twitter.com/mxcl/status/608682016205344…

Throwback to that one time Google wouldn't hire @mxcl. ;) twitter.com/mxcl/status/608682016205344… Well done Mike and contributors! It's a great piece of work.

Another favorite is so minimalist it fits in a tweet! Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

> But I didn't even apply. Perhaps this was a mistake on my part. I just had a feeling that my history of developing successful products for Google wouldn't count for much - that instead I'd get logic puzzles, quizzes about algorithmic minutiae and have to code a red-black tree on the spot on a whiteboard - all things that favor recent CS grads. Yes that seems to be how it works. twitter.com/mxcl/status/608682016205344… "Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off." My interview process with Google only made it to the technical phone screening because I didn't know the Big O complexity of read/write/sort for Trie structures. (en.wikipedia.org/wiki/Trie) The interviewer was pretty cool and we had an interesting technical discussion, so I wouldn't consider it a complete waste of time.

>Judging an entire recruitment process based on one side of a story from a person who's clearly upset about an interview, It's not just this guy. There have been others: twitter.com/mxcl/status/608682016205344… There's another measure I use to measure the quality of their hiring process. The output. Namely the track record of products Google has developed in house in the last 10 years. I've also heard a few stories about friends applying for a position and being shunted by the hiring process into the hiring funnel for other (plainly unsuitable) positions. When I hear a very specific criticism from two separate places it's hard to stay skeptical.

" (well, that and the type who doesn't actually need an interview, the famous 'oh, you have literally written the book on X, come work on X here' sort)" Well, they have a reputation for absolutely disregarding whether you are famous or not: twitter.com/mxcl/status/608682016205344…

I still remember max howel tweet[1] in which he publicly said that we was rejected by Google. Looking at his linkedin profile[2] , he was later hired by Apple in August 2015. Now he is biggest[3] contributed to Swift package manager. It is good to see that the person who has lot of experience in handing Apple and package system is handing this stuff. I guess, things happens for good. [1] twitter.com/mxcl/status/608682016205344… [2] linkedin.com/in/maxhowell [3] github.com/apple/swift-package-manager…...

Getting a job at Google as an engineer is ridiculously hard. The guy that wrote Homebrew couldn't even get hired even though 90% of their engineers use his software. twitter.com/mxcl/status/608682016205344… If you can get a job at Google, it's very different than getting a job "at a big company" and has historically actually increased your odds of success later on (via the propensity of investors to fund Xooglers). So I would definitely agree - taking a job at Google when you haven't had one before vs. starting a startup is a very legitimate choice to make. Taking a job at Microsoft vs. starting a startup, I would argue (and the X-Microsofters in my life) a very different one.

> twitter.com/mxcl/status/608687283869503… That is the killer right there. The 23 year old recruiter responds to your rejection with: "The interviewer thinks you'll be better if you get another 6 months experience. Keep practicing! We'll loop back around to you next year!" Thanks, I've been doing this for 15 years. I'm sure another 6 months is all I need to meet your delusional standards of ineffable ability.

Actually, Max himself said that it "Felt like they would have preferred a fresh comp sci grad."[1] Investment banks recruit bright young graduates, putting them through a tough selection process (c.f. all those hard-working interns we keep reading about), and select the ones who perform/conform the best. The rationale for bringing in young (as opposed to experienced) people is that they'll work their asses off, can be moulded to fit the culture (i.e. independent thinkers aren't necessarily sought), and (perhaps most importantly) are too junior to present a threat to the incumbents. If Google's going down the same path, it may be a sign that their corporate culture is solidifying, which would be a bad sign, IMHO. 1: twitter.com/mxcl/status/608698037100244…

Twitter interview went sideways, I got one shot with a question (that I won't share) that required finding Hamiltonian path in a tree, over the phone of course. I am not sure what is the mindset of the interviewer. I am hiring engineers (systems, software and security) in the last 5 years, got trained up on recruiting by Amazon, so I would say I have a pretty good understanding on hiring. The right approach with these interviews to find out the best of the candidate. In order to achieve that you always start with simple questions like what is a variable, what sort of data is out there, do you use version control etc. After that you switch gears. On the subject of inverting binary trees on a whiteboard. Is this the core of your business? How many times did you need to do that last week? If it is irrelevant for your daily operations than why are you asking this question? The problem is that (especially companies like Google) like to hire Stanford graduates and those guys think after being in the job for few months that the best way on interviewing is to measure how well the candidate would have done during the last semester in theoretical CS class at the university. While we probably all know that running a service for millions of users in production in a distributed environment requires many other skills that are not represented too much in the interviews, yet this is what you can run into during the interview loops. I think at certain extent this is known to the Google recruiting team and they are ok with it. The way to beat the interview is to read books like Cracking the Coding Interview and train up extremely well on those trees and search algos and all, if you are really committed to work there. There are several very senior guys turned down by Google simple because they failed one or two of these ridiculous questions. I think the last incident kind of a good example of this: twitter.com/mxcl/status/608682016205344… Now I get back to my read about how the heck I am inverting a binary tree.

What is your programming interview like? If it's whiteboarding algorithms, it's likely to be eliminating a lot of good people who get nervous, and selecting for people who are good at studying interview questions and coding under pressure in an artificial environment. There is good evidence it doesn't predict job performance well, see: wired.com/2015/04/hire-like-google/ and twitter.com/mxcl/status/608682016205344…

That would be Max Howell @mxcl who started Homebrew: x.com/mxcl/status/608682016205344768

The "invert a binary tree" thing is a reference to a tweet by Max Howell [1] where he complains that he didn't get hired by Google even though he wrote Homebrew, which he estimates 90% of their engineers use. Howell describes himself as a "dick" [2], hadn't been involved with the Homebrew project for years, and has since gone on to write the NFT-based package manager Tea [3] and pkgx [4], which is an "everything app"-style CLI tool with lots of fever-dream AI art and RCE as a feature. It's possible that Google just didn't hire him because he wasn't a good candidate. [1]: x.com/mxcl/status/608682016205344768 [2]: quora.com/Whats-the-logic-behind-Google…... [3]: tea.xyz/ [4]: pkgx.dev/

Most people’s “dreams” have nothing to do with working. Their dream is to have a combination of shit ton of money appear in their bank accounts every pay period and stock to appear in their brokerage account every vesting period. True there are some who want to win the lottery and accept less than their market rate in exchange for “equity” in a non public company that will statistically be worthless. Coding interviews are definitely is still the part of the process you have to pass unless you are a very well known big deal in the industry. BigTech companies want versatile developers who can move around as necessary. There are no “inside tracks” for 99% of positions aside from probably acquihires. You go through the grind regardless. Open source contributions really don’t mean that much. Infamously x.com/mxcl/status/608682016205344768?la…

Do you feel like Claptrap did?[0]. In all seriousness, good work. Sorry about the rejection, but it reminds me of the story about the Homebrew guy getting rejected by Google[1]. [0] youtu.be/hDzWw5rfefQ [1] x.com/mxcl/status/608682016205344768

“Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.” twitter.com/mxcl/status/608682016205344…

(I'm not the other poster) They're probably referring to this tweet from Max Howell [0] > Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. I personally wouldn't hold that against him (or Homebrew). We also don't really know if Google rejected him based on the binary tree, or if it was something else (personality?). [0] x.com/mxcl/status/608682016205344768 [1] news.ycombinator.com/item?id=15713801

Max Howell (the creator of Homebrew) famously was rejected from Google for failing some technical interview puzzle. [1] And it wasn’t before he created Homebrew — the interviewers knew that most of their employees used his software! I have no idea what his skills are like — maybe he can’t invert a binary tree, maybe the Homebrew code was bad, I don’t know. But either way, he wrote some code that was giving a lot of value to a lot of people. I know a rejection or two or ten can start to pick at your self confidence. But a technical interview is so far removed from what makes you a good developer that you need to resist the urge to judge yourself on that basis. [1] twitter.com/mxcl/status/608682016205344…

Reminds me of twitter.com/mxcl/status/608682016205344… , which a lot of companies still do for irrelevant positions.

twitter.com/mxcl/status/608682016205344…

As a hiring person I've interviewed great engineers with cool side projects who just weren't a good fit for the particular role I was hiring for. But also famously "I created homebrew" didn't get him a job at google. I've never had to use binary trees at work. :) twitter.com/mxcl/status/608682016205344… quora.com/Whats-the-logic-behind-Google…...

For context: twitter.com/mxcl/status/608682016205344…

Here's a possibly novel take – the modern interview process for software developers is causing more and more projects to move to these non-FOSS licensing terms. "Wait, what? What could convoluted interview processes possibly have to do with licensing?" Well, developers need to make money somehow. In the past, releasing your software as FOSS allowed you to display your skills for software development and feature planning out in the open. Often, you'd be hired on the basis of those demonstrable skills at a paying job even if you didn't make money on the product itself. Multiple engineers I know went through very abbreviated hiring processes, being pretty quickly waved through if they had worked on FOSS in any significant capacity. Today, that's not the case at all, and any interview process for a high-paying job seems to have 5-6 rounds of arduous interviews, no exceptions. I have conducted around fifty or so interview processes for dev positions at a non-FAANG company, and "look at the candidate's FOSS experience" isn't on a single one of them. I don't think I could get any major FOSS contributor exempted from a single interview process at my company on the basis of their experience. The case of the Homebrew creator and Google is reasonably well-known [1]. Well, the natural response is going to be for them to work on their own product, and not open up the source code unless they get paid for it. Which is what software devs are doing these days, in increasing numbers. ---------------------------------------- [1] twitter.com/mxcl/status/608682016205344…

Lines of code has nothing to do with the difficulty of the question, especially for recursion/backtracking types. "Invert a binary tree" is an example of an infamous question [1] that a lot of people stumble on and it's only 3 lines of code. I shouldn't have called you a liar though, just saying those are very impressive results for someone who has never done these questions before if true. [1] twitter.com/i/web/status/60868201620534…

Reminds me of this twitter.com/mxcl/status/608682016205344…

I think other responses to this thread are insightful, offer valuable ways forward and get at the heart of the matter but I wanted to add one idea that I don't think gets enough traction which is that being a "10x" developer is highly context dependent and is not a fundamental attribute of a person. Deep familiarity within a code base provides the knowledge to recognize, diagnose and fix problems at a rate that's orders of magnitude faster than someone who isn't. Familiarity with tools, corporate structure, programming idioms, toolchains or other technical factors also provide potential orders of magnitude speedup. Take a "10x" developer in one context, put them in another, and they can easily become a "1/10x" developer. One company I worked for hired an intern that had created a well used FOSS package with 10k+ GitHub stars. Though a bit of a stretch to my argument, there are other anecdotes about corporations mishandling productive programmers [0]. My point is not to lash companies too harshly but to point out that the incentives are misaligned for the skillset these programmers have versus what skillset companies need and/or are willing to pay for. My bet is that there's probably a small army of programmers that basically do mundane "1x" programming but create FOSS packages that generate millions in worth (that is, they are "10x" outside of the confines a corporate environment). As an aside, I'll mention a talk about "The Ideal Language to Write Open Source Software" [1]. On the face of it, it sounds absurd but the argument is essentially that corporate environments select for programming languages that don't need deep proficiency whereas open source software projects select for programmers with deep comprehension of their tools. In other words, corporate environments select for programmer fungability whereas open source software projects, since they often only have a single developer, select for languages that offer high productivity gains from expertise. [0] twitter.com/mxcl/status/608682016205344… [1] web.archive.org/web/20210306150046/http…...

twitter.com/mxcl/status/608682016205344…...

It was Google and not Apple. source: twitter.com/mxcl/status/608682016205344…

At FAANG? Maybe, maybe not. Definitely not without studying first. Here is the example of Max Howell who wrote Homebrew and couldn't get past the whiteboard interview at Google. twitter.com/mxcl/status/608682016205344…

Reminds me of Max Howell, creator of homebrew, when he applied to Google. His tweet: Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

It's a reference to the engineer that created homebrew but failed a google interview where they asked him that question: twitter.com/mxcl/status/608682016205344…

Reminds me of this mobile.twitter.com/mxcl/status/60868201… And many other similar stories

For me, the 'reverse a binary tree' question goes back to the creator of Homebrew being rejected from Google for not being able to answer that question: twitter.com/mxcl/status/608682016205344…

Maybe you mean this (which was about Max Howell and Google, not Apple): twitter.com/mxcl/status/608682016205344…

No, however, please note the following: Companies, like customers, have requirements for their needs. If a company needs a potential employee to know how to invert a binary tree then it's in their right to find one. In Google's case, as you're probably alluding to[0], although I might be mistaken, they've always had the reputation for seeking the best qualified people[1] for their work. I mean look at who's working for them - there's a lot of well-known people in their respective fields that are working for them. Moreover, I think that the point of these tests is to help assess a potential employee's abstract thinking. And, probably, to understand one's thought process behind the solution - if there's one - to the given problem. (Which, by the way, might be helpful if you're trying to solve AI - something that's right up in Google's alley ;). Despite the backlash over this, I believe companies will keep doing these types of tests for a long, long time. I don't think this is going away that easily. And I also think that, in the future, these tests might be done in a way you won't even know you're being tested for. [0] - twitter.com/mxcl/status/608682016205344… [1] - I understand that "best qualified" here might mean different things for different people, but you should take it literally, that is, people who are above the average in terms of abstract thinking. I suggest you read How Google Works[2], they've coined the term Smart Creative which is kind of(?) related to this. [2] - howgoogleworks.net/

My bad. I based on the tweet from the author himself [1] May be he meant to use "invert binary tree" as a representative example of questions that typically asked. [1] twitter.com/mxcl/status/608682016205344…

I believe the incident you're thinking of is the guy who wrote brew interviewing with them. twitter.com/mxcl/status/608682016205344…

Regarding Elixir specifically, the situation is much more nuanced; I went to ElixirConf last month, and the impression I came away with was that most companies present, and most speakers representing their companies, were desperate to find Elixir devs. And most attendees who already knew some Elixir were not looking to move. If there were a sudden event that caused a new army of developers to learn Elixir, such as a Harvard or MIT course switching to it, it might change this reality. But for the time being, Elixir developers are in short supply in relation to demand, so we tend to be treated (and paid) well. Our interviews are probably less frivolous, as well, because companies can’t afford to miss an opportunity to hire folks who know Elixir (or can learn it easily) just because they can’t invert a binary tree on a whiteboard (mobile.twitter.com/mxcl/status/60868201…). Timing-wise, this is probably the best time to get into Elixir, and get a head start before it reaches critical mass. Lots of interesting companies are using it, the community is fantastic, salaries and dev satisfaction are among the highest in the industry (fossbytes.com/these-programming-languag…...). And besides, it’s an amazing language and ecosystem in its own right.

reminds me of the homebrew situation > Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

> Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

If you consider homebrew a public achievement, then yes: mobile.twitter.com/mxcl/status/60868201…...

Makes me think of this: twitter.com/mxcl/status/608682016205344…

For context: twitter.com/mxcl/status/608682016205344…

Not at google: twitter.com/mxcl/status/608682016205344…

Obligatory: mobile.twitter.com/mxcl/status/60868201…...

It was the developer behind the macOS package manager Homebrew twitter.com/mxcl/status/608682016205344…

Reminds me of when Homebrew's creator can't get past Apple's interview process [1] [1] twitter.com/mxcl/status/608682016205344…

I think this was in response to this: twitter.com/mxcl/status/608682016205344…

> I don't think they will have to white-board to get a job ever again. But: twitter.com/mxcl/status/608682016205344… I think they'll never have to fizzbuzz again, but probably still lots of whiteboarding in their future.

I’m skeptical that the author would be hired and given any sort of competitive compensation. The creator of homebrew was famously rejected by Google. twitter.com/mxcl/status/608682016205344… I used to be a big believer in open source software, but as for profit enterprises continue to pillage the community without giving anything back more and more I feel that it’s not worth the time or effort involved, unless the work is protected by a proper GPLv3 license.

No? twitter.com/mxcl/status/608682016205344…

I agree with you that my gist demonstrates "table stakes", but I think that is the level of tree traversing most interview questions require. I don't think any interviewers are asking people to implement distributed algorithms like the one you linked. They are asking for algorithms that just combine a few of the basics. With that said, I'm inclined to believe our fellow commenters are arguing about the utility of what I shared. For example people siding with me gave examples of finding the biggest file in a file system and constructing a dependency graph to refute the idea that tree traversal are useless and mentioned that there isn't any "deep understanding" in BFS because it's so simple. It reminds me of the tweet by the creator of Homebrew[0] about not being able to reverse a binary tree that so many people bring up when this topic arises. To me that's just table stakes. On the topic of my example not constituting "knowing BFS", the BFS I shared is just a slight modification of what most students are taught and is close to the second method for level order traversal of a tree on geeks for geeks[1]. If you don't like the BFS usage because it isn't on an explicit tree (although nested HTML templates most definitely form a tree), the result of parsing an AspxFile in my gist returns an explicit tree data structure[2][3] and the helper method[4] at the bottom does a standard preorder traversal[5] on that linked structure. That feels like "actually using DFS on a data structure". [0] twitter.com/mxcl/status/608682016205344…... [1] geeksforgeeks.org/level-order-tree-trav… [2] gist.github.com/tohsa/2d906942f8712abdf…... [3] github.com/PositiveTechnologies/AspxPar…... (AspxParseResult has a reference to the root AspxNode, and btw I didn't write this parsing library) [4]gist.github.com/tohsa/2d906942f8712abdf…... [5] geeksforgeeks.org/dfs-traversal-of-a-tr…...

Original source: twitter.com/mxcl/status/608682016205344…

> ... when I read the crazy whiteboard interviewing, the pains people go through to get money here on HN, I would say it is pretty important. Networking won't help you get hired at a top tech company if you cannot perform well on "whiteboard interviews". It generally doesn't matter that you have an internal referral. If you don't do well on the whiteboard, it's a no-hire regardless of network. Even famous people get turned away for failing on the whiteboard. e.g. the creator of Homebrew[0] when he interviewed @ Google[1]. [0] brew.sh/ [1] twitter.com/mxcl/status/608682016205344…

> What, like homebrew? :) Context for everybody else: twitter.com/mxcl/status/608682016205344… TL;DR: author of Homebrew interviews at Google, but doesn't get hired because he couldn't/wouldn't invert a binary tree on a whiteboard.

twitter.com/mxcl/status/608682016205344…

Not GP. But I have seen these kind of studies are often suggested: researchgate.net/publication/38061313_M…... --- We synthesized evidence from interest inventories over four decades and found large sex differences in vocational interests, with men preferring working with things and women preferring working with people. --- Engineering can be said to be involved with "things" and "med schools" with people? Informally we could perhaps translate that to "Just because men like to sit in a cubicle all day and invert binary trees (a small pun on Google's hiring practices twitter.com/mxcl/status/608682016205344…) that everyone else, namely women, should enjoy doing same". I mean, they might and many do, but it is not an obvious thing like it is often presented and it should be discussed. Of course, we can then ask where do those interests come from and some will say because of how people are socialized and others will say because of hormones and other biological differences.

This is a specific, well-known case. Max Howell (the author of Brew) was rejected by Google. One of his interviewers asked him to invert a binary tree. twitter.com/mxcl/status/608682016205344…

AFAIK internal referrals at best skip the phone screen interview. As for popular open-source projects, I don't know about Guido van Rossum or Rob Pike, but Max Howell definitely whiteboarded in his interview: twitter.com/mxcl/status/608682016205344…

Or put more succinctly: twitter.com/mxcl/status/608682016205344… "Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so f* off."

ok. But You haven't answered my questions. Re that example, I was just using this famous tweet. twitter.com/mxcl/status/608682016205344… You don't get a job solving simple recursion problems. You have to solve hard leetcodes.

You're thinking of Max Howell of Homebrew fame-- twitter.com/mxcl/status/608682016205344…

That 2015 tweet (twitter.com/mxcl/status/608682016205344…) helped popularize the Google Interview memes, but things like Cracking the Code Interview still existed long before then.

> If you are a good developer who sucks at whiteboard interviews, write open source code that everybody can see. It's been done, still doesn't get you a job. twitter.com/mxcl/status/608682016205344…

It's a little in-joke twitter.com/mxcl/status/608682016205344…... Even spoofed on a recent Silicon Valley episode.

This literally happened to Max Howell, the guy behind homebrew. "Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off." twitter.com/mxcl/status/608682016205344…

I saw a tweet some time ago of the creator and main maintainer of some widely used tool (Cocoapods I think?) bombing in an interview at (Facebook|Google). He didn't pass the whiteboard test. Or maybe how Kent Beck hiring process went at FB: quora.com/How-was-Kent-Beck-recruited-t…... Edit: first case was Homebrew's creator at google: twitter.com/mxcl/status/608682016205344… (thanks, livingparadox!)

This reminds me a lot of what mxcl went through with Google twitter.com/mxcl/status/608682016205344…

I'm guessing it was a reference to this tweet: twitter.com/mxcl/status/608682016205344…

Sounds like he knows how to invert binary trees [1]. So the rest will come later... [1] - twitter.com/mxcl/status/608682016205344…

"Credentials: We're ex-Googlers and trained computer scientists. We invert binary trees [links to twitter.com/mxcl/status/608682016205344… ] for fun." Wow, way to ensure I am never, ever going to recommend this service to anyone. I am not impressed they can invert a binary tree. What is impressive is how they can manage to come across as pretentious, try-hard bullies in their own effing marketing material.

It's a reference to twitter.com/mxcl/status/608682016205344…

I wonder what this Google recruiter would say about this: twitter.com/mxcl/status/608682016205344….

When I interviewed at Google for a Ads Solutions Engineer, I had some of these questions asked as well. (I got an 8/10 and was pushed to the next round). I assume they have a massive list of questions (for various positions and have a minimum cut off - 7/10 I'm assuming as a few of my friends who got 6/10 and were not moved forward) and are asked to all applicants without consideration of experience/skill/previous work as well explained by Max Howell[0]). [0] twitter.com/mxcl/status/608682016205344…

> Recruiter: that's not the answer I have on my sheet of paper. That's not an interview. That's a waste of your time and an insult to your intelligence. This reminds me of the time Google rejected the creator of Homebrew because he couldn't invert a binary tree: twitter.com/mxcl/status/608682016205344…

Max Howell @mxcl Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off. twitter.com/mxcl/status/608682016205344…

For those who might not get the reference: twitter.com/mxcl/status/608682016205344…

a little bit more info twitter.com/mxcl/status/608698037100244… twitter.com/mxcl/status/608687283869503…

Of course, people hired after their second interview are more likely to be mediocre, because people with more options are more likely to not re-interview (like mxcl twitter.com/mxcl/status/608687283869503…)

Anybody noticed ‏an istx25 stalking each tweet-job suggestion and ultimately getting busted[1]? :D [1]: twitter.com/markmcerqueira/status/60891…

Context for the title: twitter.com/mxcl/status/608682016205344…

Matter of fact: twitter.com/mxcl/status/608682016205344…

Just one instance. twitter.com/mxcl/status/608682016205344… , I've seen hundreds like this.

twitter.com/mxcl/status/608682016205344…