12 ms·

The Problem with the FizzBuzz Problem

36 points by jasonmp85 11y ago

VLM 11y ago
The TLDR summary of the article is its really easy to get stuck down a mineshaft of "I'm sure they're looking for a more elegant way to do this". (edited to add, because scalability... demand fizzbuzz run 1...1e99 or under some weird time constraints and all bets are off, but no, its 1...100) The comment on the article of a similar example of print an ASCII art diamond claiming cleanly using symmetry is unusable sticks in my brain a bit. There's gotta be a way! I mean, there has to be, right? But my first bright ideas all involve limitations that would be very non-clean and limitation inducing, although they would be cool applications of symmetry.
- gresrun 11y ago
  This is a bit too involved for a whiteboard problem, IMO, but it isn't that hard to create a relatively clean solution: https://gist.github.com/gresrun/602bd53dad80bb51bb94 https://gist.github.com/gresrun/602bd53dad80bb51bb94
- detrino 11y ago
  I think I found the symmetry: http://ideone.com/KnaAMm http://ideone.com/KnaAMm Edit: Now with more symmetry: http://ideone.com/edNgre http://ideone.com/edNgre
  - detrino 11y ago
    Less repetition: http://ideone.com/yPQzy6 http://ideone.com/yPQzy6
lordnacho 11y ago
Here's a similarly simple question that I used on hundreds of people who were trying to get a job at a hedge fund: You have a dice (1-6). Some guy offers to pay you whatever you roll. What are you willing to pay to play this game? Somehow, most of the applicants, who all had quantitative degrees, never made it very far. It's actually a warmup (what would you pay for the same, but with a chance to re-roll once?). I just don't believe that people can't figure out the expectation of a dice roll. It makes no sense to me. Over the years I've concluded it must be because the way it's asked. People think there's something deeper in it than the most straightforward explanation. Or maybe they think they missed some critical detail and are afraid to ask. Now there are actually some clarifications that would make it more interesting, but I never got anyone to ask those (Is it an eternal game? Do I have a limited pot?). What was really dispiriting was when someone understood it, and were shocked we'd asked it.
- JoeAltmaier 11y ago
  I'm willing to pay $0! No, really, statistics are unintuitive and most people, smart people, don't have a feel for them. Just look at the HN thrash whenever the Monty Hall problem comes up. Btw its a 'die'. 'Dice' is plural.
  - apalmer 11y ago
    Yeah but he specifically said these are folks with quantitative degrees... I would expect want to be quants applying at a hedge fund to have an understanding of statistics.
    - lordnacho 11y ago
      Or high school students with a class in basic probability. All I was after was the expectation, just as a quick warmup. No fancy talking about utility functions and all that. And it really was meant to make people feel at ease.
    - meragrin 11y ago
      Yes, but there is a difference between expected payout and a person's willingness to play a game of chance. The expected payout of a lottery ticket is the same for every ticket before the drawing, but everyone has a different willingness to purchase tickets. The person is being asked about their willingness to take on risk and not their objective analysis of the payout.
  - dragonwriter 11y ago
    > Btw its a 'die'. 'Dice' is plural. Most current dictionaries disagree and accept either "die" or "dice" as singular, with "dice" also being plural.
    - JoeAltmaier 11y ago
      Yes, I'm sure in usage, dice is abused constantly.
JoeAltmaier 11y ago
My sister's question was, how many Ping-Pong balls fit in a semi trailer? She would add no details. The idea was, could they function with limited info, make assumptions, come up with any answer at all. Most couldn't.
- bobbytherobot 11y ago
  My follow up question if I was in that interview would be, "Is this how you operate, do you not provide critical information or am I a researcher?"
  - JoeAltmaier 11y ago
    Nobody gets all the info they need. You have to learn to operate by your wits. This was in a trucking/hauling company, with 1000's of people on the road responding to situations that changed constantly.
  - mikeash 11y ago
    My follow up to that follow up would be, it's 2015, internet access is ubiquitous, and if you can't find the dimensions of a standard ping pong ball and a standard semi trailer without having your hand held, then we don't need your services.
    - oinksoft 11y ago
      Note that ping-pong balls can be crushed or melted. Anyway, your reply establishes a weird power dynamic so if that's really how you do business, the candidate dodges a bullet by your forthrightness.
      - mikeash 11y ago
        What's weird about expecting one's employees to be capable of looking up basic facts on their own?
        11y ago
hvs 11y ago
This also points to a situation that I sometimes find myself, where I try to be "clever" in solving a problem and, even if the solution works, is ultimately more confusing than the straightforward method. As I've maintained more code in my life, I've learned to shy away from being "clever", but it's always there in the back of my mind. I think this is one of the challenges of functional programming as well. It allows you to be really clever, to the point of unintelligibility.
bobbytherobot 11y ago
I've seen people fail questions for this reason. We even tell them not to go down a certain path, or not to worry about optimizing the solution. But they keep on trying to go down the clever path.
- Sevzinn 11y ago
  The problem is ego. People don't act like the JSON that computers think like. An array in JSON can represent an unordered set, but people order it according to how they can become superior to others. People should be more like JSON.
  - MichaelGG 11y ago
    > People should be more like JSON. So needlessly verbose and unable to handle comments? Oh, and unable to intrinsically distinguish dates from text, or real numbers from integers?
    - Sevzinn 11y ago
      5.0 is real. 5 is integer.
apalmer 11y ago
This 'problem' with FizzBuzz is really a 'benefit'. I have seen it time and time again, incredible complex code by intelligent people attempting to chase an 'elegant' design. Literally its my number one problem with senior developers where I work, refusal to leave working simple readable solutions alone.
- chwahoo 11y ago
  But as she points out, FizzBuzz doesn't do a good job in telling you if you've found one of these developers because the context of interviewing is different than the context of banging out code on the job.
buro9 11y ago
> However, I have yet to see one that would actually be better in the real world than the simple, obvious solution. Use counters, avoid modulo, and see a significant performance increase. Computers suck at division, and FizzBuzz doesn't need division. The solution is perhaps simpler than the obvious one as even a child could explain how it works. https://gist.github.com/buro9/5345664#file-fizzbuzz-html https://gist.github.com/buro9/5345664#file-fizzbuzz-html On my laptop, in Firefox: Fast: 203ms Slow: 844ms
- thedufer 11y ago
  That depends on how you're defining better. The slow one is somewhat more readable, and since your test runs a million times farther than the 100 that FizzBuzz usually asks for, you're looking at a gain of .6 μs. That's an interesting set of priorities, unless you know something about how often this code runs.
  - buro9 11y ago
    I'm not sure anyone imagines running FizzBuzz in production. It is an interview tool only, first to determine whether the candidate can program, but which can also be used as a basis for some interview questions. The counter example helps to answer whether the candidate understands how numbers are represented by computers and how addition and division function. It also helps to answer whether a candidate knows what, in such trivial code, could (not must) be optimised were the value of n to increase insignificantly. As you say, probing questions about how often the code runs, what the value of n is, or various other questions will all vary the answer. But to suggest that the priorities are wrong is a little silly, most interview questions are wrong to some definition.
- blacksmythe 11y ago
  >> Use counters, avoid modulo, That is also my solution (although I would use only two counters). Having a background in hardware engineering and hardware optimization, using a modulo operation unnecessarily seems completely foreign to me.
jasode 11y ago
>But the smart developer might just identify (intelligently) the potential for a "cool, elegant" solution and never find it. ... They think you want an elegant solution because the simple one is too obvious and it feels like there is an elegant solution. I think this is the gist of the essay and it's very easily addressed by stating at the beginning, "just code something that works, don't try to come up with the most elegant thing known to mankind." I don't see this as an issue in real life if some commmon-sense parameters are spelled out upfront. It's a 5-minute sanity check to get past false resumes. That's it. I guess it's theoretically possible for an algorithms-obsessed programmer to sit there paralyzed for 2 hours on fizzbuzz. You the interviewer then ask him, "is there something about modulus 3 and 5 that's tripping you up?" He says "Oh, not at all. I was just debating whether I should start with first principles of lambda calculus and have the program replicate itself in millions of successive genetic iterations until the final program writes itself. But then I got on a thought tangent and was thinking if I could just manually write list of the first 100 correct answers and then feed that to a machine learning algorithm that I write. It would classify the intervals and work backward via artificial intelligence to generate the right program. Btw, how much time do I get to work on this?" I suppose scenarios like that could happen, but I don't worry about it.
- hahamrfunnyguy 11y ago
  Agreed. I was presented a simple challenge during an interview and my first question: Can I brute force the solution? Interviewer's answer: Sure, as long as it works. I think if the developer doesn't know when to ask the right questions, it hints at a deeper problem.
- chucksmash 11y ago
  I've seen several projects already that were killed by very smart people doing exactly this, writ large. Maybe it's an uninspired view point but I don't think filtering out that hypothetical candidate is necessarily a bad thing either.
- talmand 11y ago
  I once was doing something very similar to that until I realized it would be more efficient to manually write the sequence to 100 places on a piece of notebook paper instead.
imron 11y ago
'The problem with using light grey text on a white background' would also make an excellent article topic.
MollyR 11y ago
Yea I don't know how I feel about this article. I know my team lead asks FizzBuzz to all new hires, and he's looking for elegance and robustness even in simple designs because when we work on our complex systems, it matters a lot for having a good code base. Just the fact they think in terms larger than just the basic code is what I think he looks for.
kstenerud 11y ago
> The dumb (or lazy or new) developer will not notice or care about the appearance of a potential cool solution. They'll just bang out whatever works. The pragmatic programmer (aka the person I want to hire) would also not care about the appearance of a potential cool solution, because experience teaches us that clever solutions tend to increase complexity and cognitive load, increasing not only the bug count, but also maintenance costs. Yes, by all means be clever where it's warranted (strange constraints, bottlenecks, etc), but please not in regular code!
- gharial 11y ago
  I really couldn't follow his logic at all. Being able to come up with a working (perfectly correct) solution somehow implies a developer is probably "dumb" or "lazy"? As if a truly "smart" or gifted programmer would be unable to come up with a solution because they're just oh so intelligent and clever. You either know how loops work or you don't.
  - JoeAltmaier 11y ago
    Most smart programmers I know would prefer to product a good, or even the best, solution instead of any of the prosaic solutions. Unable to come up with a solution? Probably not. All the given examples are pedestrian. A really clever solution would recurse or search the web for a matching solution page or hash the solution space into a minimal table or something like that. But agreed a proper programmer would never fail to produce a correct solution.
    - kstenerud 11y ago
      That's sort of what I'm getting at. There are two kinds of smart programmers: Those who look for every opportunity to be clever, and those who are satisfied to build pedestrian solutions until clever code is called for. If you're going to build a clever solution (which almost by definition increases cognitive load on anyone reading or maintaining the code), you'd better be able to defend your actions. Performance is never a problem until it's demonstrated to be a problem.
kelukelugames 11y ago
I can't wait for someone to ask me a fizz buzz question. I am going to write this out: switch n case 1: case 2: print n case 3: print "fizz" it's going to be so much fun.
henrikschroder 11y ago
1) If you're doing FizzBuzz at an on-site interview, you've failed in your process. FizzBuzz is something you use as early as possible to weed out clearly incompetent developers. 2) I can see how a clever developer might get stuck in analysis paralysis, but even then you should be able to coax them out of it, and at least get them to write down a little bit of code that does a loop and an if statement, because that's what we're really checking: Can this individual write working code from scratch? (And if you can't coax them out of it for this, how the hell are you going to be able to do the same for real problems?)
- talmand 11y ago
  But how do you administer something FizzBuzz outside of an on-site interview? How do you know they actually completed the task without being with them when they did? I'm guessing Skype interview or something similar?
  - henrikschroder 11y ago
    I'm using a simple shared editor such as collabedit or similar. You send the link to the shared space along with the phone number for the interview, and you let the candidate know that there will be some simple shared exercises so they need to be at a computer. And then you ask your questions, and do FizzBuzz or similar, and watch them code.
kstrauser 11y ago
If I interview you, you're getting FizzBuzz. I also lay down some ground rules: - Write it in the language of your choice. It's OK if I don't know that language but be prepared to explain unfamiliar stuff to me. - I am not a compiler and I don't care about semicolons, misspellings, etc. as long as I can understand the point of the code. - There aren't any tricks. This is the whole problem. I do not say anything like "keep it simple" because that can kick candidates into "OH GOD THERE MUST BE A ONE-LINER AND I CAN'T SEE IT" mode. My goal is to make the candidate as comfortable as possible in a potentially stressful situation. I want to give them every chance to succeed. I've seen people with 10 years as a lead engineer fail horribly. I've seen people blanch at the concept of loops. Loops! The most common failure mode I've seen is for candidates to start throwing in lots of state variables like "is_divisible_by_3" and "has_printed_the_word_fizz", even after I prompt them toward using "else if" or nested if statements. One guy laughed and said, "I've done this 100 times. Do I really have to?" I laughed, too, and replied "OK, just tell me what you'd do." He spat out some pseudocode that would've worked, I apologized and explained why I make everyone do this, and we swapped funny stories. My company made an offer that day, he accepted, and is still successful in that role. I've also had people complain that this is beneath them. Too bad. You're asking us to pay 6 figures for your programming skills? Then be prepared to spend 5 minutes demonstrating them. Your GitHub repo may be a clone of other peoples' work for all I know. I can and have ended interviews with candidates who dig in their heels and won't cooperate.
- jknipp 11y ago
  I've started including a small variation of FizzBuzz as part of our developer screening test - varied so you can't copy and paste from google. Very loose guidelines, pick your language, access to the internet, etc. We even give a general outline of what will be tested 24 hours out, and no hard time limit. 3 out of 4 people so far were unable to do the test. One guy boasted 20+ years of development experience and I used to work with him, he didn't even attempt it?!? Frankly, I expect candidates of any worth to feel insulted we are asking them to write this. The guy that did complete it wrote it in Bash, and wasn't strong in that to begin with. Bonus points for learning a language on the fly, that's what I'm looking for.
ilitirit 11y ago
I did an experiment while interviewing interns once. For half the group, I posed this problem: > Given a log file, with each line prefixed with either WARN, INFO, ERROR or DEBUG, explain briefly how you would determine the number of errors logged assuming that each line corresponds to a single event and vice versa. For the other half, I posed the same question, but I said the log file was 50MB big. Most people didn't know how to solve the second problem even though given the scales involved the solution is essentially the same. (By the way, the question wasn't used as part of the criteria for the job)
- imaginenore 11y ago
  No, the solution is not the same. The 50MB one is easier, as it fits in RAM and we know none of the counts exceed 25 million. With the first one we don't even know if the counts fit into the standard numeric types.
  - MichaelGG 11y ago
    Considering how easy it is to get a linear implementation, why would anyone choose to use a slower method?
- TheLoneWolfling 11y ago
  Those two are not equivalent. Actually, I'm surprised that people didn't find the first one harder: I've had log files that were larger than RAM before (mainly due to overzealous logging).
  - userbinator 11y ago
    If the first thing your solution does is attempt to read the entire file into memory, then you probably failed the test. The same goes for trying to read an entire line into memory, however long it may be - this is a problem that can be solved with an essentially constant space of around a dozen bytes.
  - kstrauser 11y ago
    Exactly! I've been asked the followup question: "now assume that you have 8 petabytes of log files to search", which leads into distributed computing, realtime vs on-demand collection, eventually consistent counters, the pros and cons of sampling vs exact counts, and so on. The unbounded form of that question can be astonishingly hard, and for the kinds of jobs I'd be interviewing for I'd expect the challenging next questions. I'd still answer along the lines of "for a quick solution I'd grep for the error level and count the number of lines, but that's not scalable".
brudgers 11y ago
Internationalization suggests that "Fizz" and "Buzz" be parameterized...and maybe we shouldn't hard code "3" and since magic numbers aren't good practice either...and the possibility of a different search function for the "FizzBuzz" suggests parameterizing that value, too. Which is to say that one of the problems with FizzBuzz is that the interviewer doesn't take it seriously enough to care about engineering practice at the level that matters. If they did, FizzBuzz would come with a test suite.
- jameshart 11y ago
  So if you're asked to do fizzbuzz in an interview, feel free to bring these things up. Just don't make it seem like you're looking for excuses not to write code. If you approach fizzbuzz by saying 'okay, so you want me to write a program that generates this sequence on demand - otherwise we could just precalculate all 100 values - so I'm going to assume that you want something parameterizable. How about we make it take a dictionary of factors that map to certain keywords, and we take { 3: "Fizz", 5: "Buzz" } as an initial testcase?' I'm going to go along with that, so long as the code you write actually works. I might walk you back from internationalizing the output, but points for mentioning it.
  - TheLoneWolfling 11y ago
    That better be an ordered map, there.
  - brudgers 11y ago
    FizzBuzz suffers from the StackOverflow fastest fingers on the internet problem, it favors cursory poorly engineered solutions. By which I mean what is FizzBuzz supposed to do if IO blocks because stdout got redirected to a resource that's not available? When the code the interviewer wants to see has IO operations spaghettied throughout the business logic rather than separated as a concern, is the exercise selecting for people who are perfectly willing to do only what is asked rather than what is needed? How many lines of code would FizzBuzz really be if we were serious about it as Engineers?
    - 11y ago
z3t4 11y ago
I think every programmer goes through the "smart" stage, where you start to get confident and write "clever" solutions for simple problems. Where you will hopefully transcend to writing simple solutions for hard problems. Personally I hate stupid tests like these, just give me a real life problem that you are currently working on ... Here's my fizzbuzz solution: https://github.com/Z3TA/fizzbuzz/blob/master/fizzbuzz.js https://github.com/Z3TA/fizzbuzz/blob/master/fizzbuzz.js And here's my favorite one, on how it would look like if implemented like most "enterprise code" looks like: https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpriseEdition https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpris...
sopooneo 11y ago
Out of curiousity, what is an elegant solution for her problem of finding out what year had the most people alive? I can think of a couple brute force methods, but I've not been able to phrase the question properly to find an ideal solution on Google.
- gaylemcd 11y ago
  Here's a solution that takes O(P + R) time, where P is the number of people and R is the total range of birth years. First, notice that you don't really care who died when. All that matters is someone died. People's birth and death years are fungible, in a sense. Each birth increases the population by one and each death increases the population by one. Basically, you'll create an array where the value at each index represents how much the population changed in that year (steps 1 to 3). Then you can use that array to find the highest population (step 4). 1. Get the min birth year and the max birth year. 2. Create an array where the size is the above range. Set to all zeros. Each index will map to / represent a year in the range. 3. Loop through all the people. For each person, increment the index of their birth year and decrement their death year (or the following year, depending on whether or not they're counted as alive the entire year of their death) 4. Just loop through the array, tracking the running sum at each index. The biggest running sum will indicate the highest population. There are some other good solutions depending on what assumptions you make about P and R's relative size.
  - TheLoneWolfling 11y ago
    Hmm... If you sort everyone's births and deaths you can just walk through the array keeping track of the number of people alive at each point and the maximum number of people alive at any point (and the year(s) thereof). O(P log P) (from the sort), no explicit dependance on R. Are there any other good solutions? I cannot imagine that there would be anything that's sublinear in P, so about the only other thing I could imagine would be something that is linear in P and sublinear in R.
    - gaylemcd 11y ago
      Yes, that's another good solution. You can't really compare O(P + R) and O(P log P). Of course, you could argue that P could grow a lot faster than R, so O(P + R) would be better. That's probably true in a "real world" sense, but not in a mathematical sense.
dlandis 11y ago
In my experience after reading her book and some of her articles I think Gayle (and many other interviewers) underestimates the effect nerves have on certain people. She may be a little too quick to classify certain people as "dumb" when, in fact, some people's brains just totally freeze up during traditional coding interviews. I suspect more outgoing, extroverted people have a hard time fathoming what that's like or even that it is possible.

36 points by jasonmp85 11y ago

VLM 11y ago

The TLDR summary of the article is its really easy to get stuck down a mineshaft of "I'm sure they're looking for a more elegant way to do this". (edited to add, because scalability... demand fizzbuzz run 1...1e99 or under some weird time constraints and all bets are off, but no, its 1...100) The comment on the article of a similar example of print an ASCII art diamond claiming cleanly using symmetry is unusable sticks in my brain a bit. There's gotta be a way! I mean, there has to be, right? But my first bright ideas all involve limitations that would be very non-clean and limitation inducing, although they would be cool applications of symmetry.

gresrun 11y ago
This is a bit too involved for a whiteboard problem, IMO, but it isn't that hard to create a relatively clean solution: https://gist.github.com/gresrun/602bd53dad80bb51bb94 https://gist.github.com/gresrun/602bd53dad80bb51bb94
detrino 11y ago
I think I found the symmetry: http://ideone.com/KnaAMm http://ideone.com/KnaAMm Edit: Now with more symmetry: http://ideone.com/edNgre http://ideone.com/edNgre
- detrino 11y ago
  Less repetition: http://ideone.com/yPQzy6 http://ideone.com/yPQzy6

lordnacho 11y ago

Here's a similarly simple question that I used on hundreds of people who were trying to get a job at a hedge fund: You have a dice (1-6). Some guy offers to pay you whatever you roll. What are you willing to pay to play this game? Somehow, most of the applicants, who all had quantitative degrees, never made it very far. It's actually a warmup (what would you pay for the same, but with a chance to re-roll once?). I just don't believe that people can't figure out the expectation of a dice roll. It makes no sense to me. Over the years I've concluded it must be because the way it's asked. People think there's something deeper in it than the most straightforward explanation. Or maybe they think they missed some critical detail and are afraid to ask. Now there are actually some clarifications that would make it more interesting, but I never got anyone to ask those (Is it an eternal game? Do I have a limited pot?). What was really dispiriting was when someone understood it, and were shocked we'd asked it.

JoeAltmaier 11y ago
I'm willing to pay $0! No, really, statistics are unintuitive and most people, smart people, don't have a feel for them. Just look at the HN thrash whenever the Monty Hall problem comes up. Btw its a 'die'. 'Dice' is plural.
- apalmer 11y ago
  Yeah but he specifically said these are folks with quantitative degrees... I would expect want to be quants applying at a hedge fund to have an understanding of statistics.
  - lordnacho 11y ago
    Or high school students with a class in basic probability. All I was after was the expectation, just as a quick warmup. No fancy talking about utility functions and all that. And it really was meant to make people feel at ease.
  - meragrin 11y ago
    Yes, but there is a difference between expected payout and a person's willingness to play a game of chance. The expected payout of a lottery ticket is the same for every ticket before the drawing, but everyone has a different willingness to purchase tickets. The person is being asked about their willingness to take on risk and not their objective analysis of the payout.
- dragonwriter 11y ago
  > Btw its a 'die'. 'Dice' is plural. Most current dictionaries disagree and accept either "die" or "dice" as singular, with "dice" also being plural.
  - JoeAltmaier 11y ago
    Yes, I'm sure in usage, dice is abused constantly.

JoeAltmaier 11y ago

My sister's question was, how many Ping-Pong balls fit in a semi trailer? She would add no details. The idea was, could they function with limited info, make assumptions, come up with any answer at all. Most couldn't.

bobbytherobot 11y ago
My follow up question if I was in that interview would be, "Is this how you operate, do you not provide critical information or am I a researcher?"
- JoeAltmaier 11y ago
  Nobody gets all the info they need. You have to learn to operate by your wits. This was in a trucking/hauling company, with 1000's of people on the road responding to situations that changed constantly.
- mikeash 11y ago
  My follow up to that follow up would be, it's 2015, internet access is ubiquitous, and if you can't find the dimensions of a standard ping pong ball and a standard semi trailer without having your hand held, then we don't need your services.
  - oinksoft 11y ago
    Note that ping-pong balls can be crushed or melted. Anyway, your reply establishes a weird power dynamic so if that's really how you do business, the candidate dodges a bullet by your forthrightness.
    - mikeash 11y ago
      What's weird about expecting one's employees to be capable of looking up basic facts on their own?
      - 11y ago

hvs 11y ago

This also points to a situation that I sometimes find myself, where I try to be "clever" in solving a problem and, even if the solution works, is ultimately more confusing than the straightforward method. As I've maintained more code in my life, I've learned to shy away from being "clever", but it's always there in the back of my mind. I think this is one of the challenges of functional programming as well. It allows you to be really clever, to the point of unintelligibility.

bobbytherobot 11y ago

I've seen people fail questions for this reason. We even tell them not to go down a certain path, or not to worry about optimizing the solution. But they keep on trying to go down the clever path.

Sevzinn 11y ago
The problem is ego. People don't act like the JSON that computers think like. An array in JSON can represent an unordered set, but people order it according to how they can become superior to others. People should be more like JSON.
- MichaelGG 11y ago
  > People should be more like JSON. So needlessly verbose and unable to handle comments? Oh, and unable to intrinsically distinguish dates from text, or real numbers from integers?
  - Sevzinn 11y ago
    5.0 is real. 5 is integer.

apalmer 11y ago

This 'problem' with FizzBuzz is really a 'benefit'. I have seen it time and time again, incredible complex code by intelligent people attempting to chase an 'elegant' design. Literally its my number one problem with senior developers where I work, refusal to leave working simple readable solutions alone.

chwahoo 11y ago
But as she points out, FizzBuzz doesn't do a good job in telling you if you've found one of these developers because the context of interviewing is different than the context of banging out code on the job.

buro9 11y ago

> However, I have yet to see one that would actually be better in the real world than the simple, obvious solution. Use counters, avoid modulo, and see a significant performance increase. Computers suck at division, and FizzBuzz doesn't need division. The solution is perhaps simpler than the obvious one as even a child could explain how it works. https://gist.github.com/buro9/5345664#file-fizzbuzz-html https://gist.github.com/buro9/5345664#file-fizzbuzz-html On my laptop, in Firefox: Fast: 203ms Slow: 844ms

thedufer 11y ago
That depends on how you're defining better. The slow one is somewhat more readable, and since your test runs a million times farther than the 100 that FizzBuzz usually asks for, you're looking at a gain of .6 μs. That's an interesting set of priorities, unless you know something about how often this code runs.
- buro9 11y ago
  I'm not sure anyone imagines running FizzBuzz in production. It is an interview tool only, first to determine whether the candidate can program, but which can also be used as a basis for some interview questions. The counter example helps to answer whether the candidate understands how numbers are represented by computers and how addition and division function. It also helps to answer whether a candidate knows what, in such trivial code, could (not must) be optimised were the value of n to increase insignificantly. As you say, probing questions about how often the code runs, what the value of n is, or various other questions will all vary the answer. But to suggest that the priorities are wrong is a little silly, most interview questions are wrong to some definition.
blacksmythe 11y ago
>> Use counters, avoid modulo, That is also my solution (although I would use only two counters). Having a background in hardware engineering and hardware optimization, using a modulo operation unnecessarily seems completely foreign to me.

jasode 11y ago

>But the smart developer might just identify (intelligently) the potential for a "cool, elegant" solution and never find it. ... They think you want an elegant solution because the simple one is too obvious and it feels like there is an elegant solution. I think this is the gist of the essay and it's very easily addressed by stating at the beginning, "just code something that works, don't try to come up with the most elegant thing known to mankind." I don't see this as an issue in real life if some commmon-sense parameters are spelled out upfront. It's a 5-minute sanity check to get past false resumes. That's it. I guess it's theoretically possible for an algorithms-obsessed programmer to sit there paralyzed for 2 hours on fizzbuzz. You the interviewer then ask him, "is there something about modulus 3 and 5 that's tripping you up?" He says "Oh, not at all. I was just debating whether I should start with first principles of lambda calculus and have the program replicate itself in millions of successive genetic iterations until the final program writes itself. But then I got on a thought tangent and was thinking if I could just manually write list of the first 100 correct answers and then feed that to a machine learning algorithm that I write. It would classify the intervals and work backward via artificial intelligence to generate the right program. Btw, how much time do I get to work on this?" I suppose scenarios like that could happen, but I don't worry about it.

hahamrfunnyguy 11y ago
Agreed. I was presented a simple challenge during an interview and my first question: Can I brute force the solution? Interviewer's answer: Sure, as long as it works. I think if the developer doesn't know when to ask the right questions, it hints at a deeper problem.
chucksmash 11y ago
I've seen several projects already that were killed by very smart people doing exactly this, writ large. Maybe it's an uninspired view point but I don't think filtering out that hypothetical candidate is necessarily a bad thing either.
talmand 11y ago
I once was doing something very similar to that until I realized it would be more efficient to manually write the sequence to 100 places on a piece of notebook paper instead.

imron 11y ago

'The problem with using light grey text on a white background' would also make an excellent article topic.

MollyR 11y ago

Yea I don't know how I feel about this article. I know my team lead asks FizzBuzz to all new hires, and he's looking for elegance and robustness even in simple designs because when we work on our complex systems, it matters a lot for having a good code base. Just the fact they think in terms larger than just the basic code is what I think he looks for.

kstenerud 11y ago

> The dumb (or lazy or new) developer will not notice or care about the appearance of a potential cool solution. They'll just bang out whatever works. The pragmatic programmer (aka the person I want to hire) would also not care about the appearance of a potential cool solution, because experience teaches us that clever solutions tend to increase complexity and cognitive load, increasing not only the bug count, but also maintenance costs. Yes, by all means be clever where it's warranted (strange constraints, bottlenecks, etc), but please not in regular code!

gharial 11y ago
I really couldn't follow his logic at all. Being able to come up with a working (perfectly correct) solution somehow implies a developer is probably "dumb" or "lazy"? As if a truly "smart" or gifted programmer would be unable to come up with a solution because they're just oh so intelligent and clever. You either know how loops work or you don't.
- JoeAltmaier 11y ago
  Most smart programmers I know would prefer to product a good, or even the best, solution instead of any of the prosaic solutions. Unable to come up with a solution? Probably not. All the given examples are pedestrian. A really clever solution would recurse or search the web for a matching solution page or hash the solution space into a minimal table or something like that. But agreed a proper programmer would never fail to produce a correct solution.
  - kstenerud 11y ago
    That's sort of what I'm getting at. There are two kinds of smart programmers: Those who look for every opportunity to be clever, and those who are satisfied to build pedestrian solutions until clever code is called for. If you're going to build a clever solution (which almost by definition increases cognitive load on anyone reading or maintaining the code), you'd better be able to defend your actions. Performance is never a problem until it's demonstrated to be a problem.

kelukelugames 11y ago

I can't wait for someone to ask me a fizz buzz question. I am going to write this out: switch n case 1: case 2: print n case 3: print "fizz" it's going to be so much fun.

henrikschroder 11y ago

1) If you're doing FizzBuzz at an on-site interview, you've failed in your process. FizzBuzz is something you use as early as possible to weed out clearly incompetent developers. 2) I can see how a clever developer might get stuck in analysis paralysis, but even then you should be able to coax them out of it, and at least get them to write down a little bit of code that does a loop and an if statement, because that's what we're really checking: Can this individual write working code from scratch? (And if you can't coax them out of it for this, how the hell are you going to be able to do the same for real problems?)

talmand 11y ago
But how do you administer something FizzBuzz outside of an on-site interview? How do you know they actually completed the task without being with them when they did? I'm guessing Skype interview or something similar?
- henrikschroder 11y ago
  I'm using a simple shared editor such as collabedit or similar. You send the link to the shared space along with the phone number for the interview, and you let the candidate know that there will be some simple shared exercises so they need to be at a computer. And then you ask your questions, and do FizzBuzz or similar, and watch them code.

kstrauser 11y ago

If I interview you, you're getting FizzBuzz. I also lay down some ground rules: - Write it in the language of your choice. It's OK if I don't know that language but be prepared to explain unfamiliar stuff to me. - I am not a compiler and I don't care about semicolons, misspellings, etc. as long as I can understand the point of the code. - There aren't any tricks. This is the whole problem. I do not say anything like "keep it simple" because that can kick candidates into "OH GOD THERE MUST BE A ONE-LINER AND I CAN'T SEE IT" mode. My goal is to make the candidate as comfortable as possible in a potentially stressful situation. I want to give them every chance to succeed. I've seen people with 10 years as a lead engineer fail horribly. I've seen people blanch at the concept of loops. Loops! The most common failure mode I've seen is for candidates to start throwing in lots of state variables like "is_divisible_by_3" and "has_printed_the_word_fizz", even after I prompt them toward using "else if" or nested if statements. One guy laughed and said, "I've done this 100 times. Do I really have to?" I laughed, too, and replied "OK, just tell me what you'd do." He spat out some pseudocode that would've worked, I apologized and explained why I make everyone do this, and we swapped funny stories. My company made an offer that day, he accepted, and is still successful in that role. I've also had people complain that this is beneath them. Too bad. You're asking us to pay 6 figures for your programming skills? Then be prepared to spend 5 minutes demonstrating them. Your GitHub repo may be a clone of other peoples' work for all I know. I can and have ended interviews with candidates who dig in their heels and won't cooperate.

jknipp 11y ago
I've started including a small variation of FizzBuzz as part of our developer screening test - varied so you can't copy and paste from google. Very loose guidelines, pick your language, access to the internet, etc. We even give a general outline of what will be tested 24 hours out, and no hard time limit. 3 out of 4 people so far were unable to do the test. One guy boasted 20+ years of development experience and I used to work with him, he didn't even attempt it?!? Frankly, I expect candidates of any worth to feel insulted we are asking them to write this. The guy that did complete it wrote it in Bash, and wasn't strong in that to begin with. Bonus points for learning a language on the fly, that's what I'm looking for.

ilitirit 11y ago

I did an experiment while interviewing interns once. For half the group, I posed this problem: > Given a log file, with each line prefixed with either WARN, INFO, ERROR or DEBUG, explain briefly how you would determine the number of errors logged assuming that each line corresponds to a single event and vice versa. For the other half, I posed the same question, but I said the log file was 50MB big. Most people didn't know how to solve the second problem even though given the scales involved the solution is essentially the same. (By the way, the question wasn't used as part of the criteria for the job)

imaginenore 11y ago
No, the solution is not the same. The 50MB one is easier, as it fits in RAM and we know none of the counts exceed 25 million. With the first one we don't even know if the counts fit into the standard numeric types.
- MichaelGG 11y ago
  Considering how easy it is to get a linear implementation, why would anyone choose to use a slower method?
TheLoneWolfling 11y ago
Those two are not equivalent. Actually, I'm surprised that people didn't find the first one harder: I've had log files that were larger than RAM before (mainly due to overzealous logging).
- userbinator 11y ago
  If the first thing your solution does is attempt to read the entire file into memory, then you probably failed the test. The same goes for trying to read an entire line into memory, however long it may be - this is a problem that can be solved with an essentially constant space of around a dozen bytes.
- kstrauser 11y ago
  Exactly! I've been asked the followup question: "now assume that you have 8 petabytes of log files to search", which leads into distributed computing, realtime vs on-demand collection, eventually consistent counters, the pros and cons of sampling vs exact counts, and so on. The unbounded form of that question can be astonishingly hard, and for the kinds of jobs I'd be interviewing for I'd expect the challenging next questions. I'd still answer along the lines of "for a quick solution I'd grep for the error level and count the number of lines, but that's not scalable".

brudgers 11y ago

Internationalization suggests that "Fizz" and "Buzz" be parameterized...and maybe we shouldn't hard code "3" and since magic numbers aren't good practice either...and the possibility of a different search function for the "FizzBuzz" suggests parameterizing that value, too. Which is to say that one of the problems with FizzBuzz is that the interviewer doesn't take it seriously enough to care about engineering practice at the level that matters. If they did, FizzBuzz would come with a test suite.

jameshart 11y ago
So if you're asked to do fizzbuzz in an interview, feel free to bring these things up. Just don't make it seem like you're looking for excuses not to write code. If you approach fizzbuzz by saying 'okay, so you want me to write a program that generates this sequence on demand - otherwise we could just precalculate all 100 values - so I'm going to assume that you want something parameterizable. How about we make it take a dictionary of factors that map to certain keywords, and we take { 3: "Fizz", 5: "Buzz" } as an initial testcase?' I'm going to go along with that, so long as the code you write actually works. I might walk you back from internationalizing the output, but points for mentioning it.
- TheLoneWolfling 11y ago
  That better be an ordered map, there.
- brudgers 11y ago
  FizzBuzz suffers from the StackOverflow fastest fingers on the internet problem, it favors cursory poorly engineered solutions. By which I mean what is FizzBuzz supposed to do if IO blocks because stdout got redirected to a resource that's not available? When the code the interviewer wants to see has IO operations spaghettied throughout the business logic rather than separated as a concern, is the exercise selecting for people who are perfectly willing to do only what is asked rather than what is needed? How many lines of code would FizzBuzz really be if we were serious about it as Engineers?
  - 11y ago

z3t4 11y ago

I think every programmer goes through the "smart" stage, where you start to get confident and write "clever" solutions for simple problems. Where you will hopefully transcend to writing simple solutions for hard problems. Personally I hate stupid tests like these, just give me a real life problem that you are currently working on ... Here's my fizzbuzz solution: https://github.com/Z3TA/fizzbuzz/blob/master/fizzbuzz.js https://github.com/Z3TA/fizzbuzz/blob/master/fizzbuzz.js And here's my favorite one, on how it would look like if implemented like most "enterprise code" looks like: https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpriseEdition https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpris...

sopooneo 11y ago

Out of curiousity, what is an elegant solution for her problem of finding out what year had the most people alive? I can think of a couple brute force methods, but I've not been able to phrase the question properly to find an ideal solution on Google.

gaylemcd 11y ago
Here's a solution that takes O(P + R) time, where P is the number of people and R is the total range of birth years. First, notice that you don't really care who died when. All that matters is someone died. People's birth and death years are fungible, in a sense. Each birth increases the population by one and each death increases the population by one. Basically, you'll create an array where the value at each index represents how much the population changed in that year (steps 1 to 3). Then you can use that array to find the highest population (step 4). 1. Get the min birth year and the max birth year. 2. Create an array where the size is the above range. Set to all zeros. Each index will map to / represent a year in the range. 3. Loop through all the people. For each person, increment the index of their birth year and decrement their death year (or the following year, depending on whether or not they're counted as alive the entire year of their death) 4. Just loop through the array, tracking the running sum at each index. The biggest running sum will indicate the highest population. There are some other good solutions depending on what assumptions you make about P and R's relative size.
- TheLoneWolfling 11y ago
  Hmm... If you sort everyone's births and deaths you can just walk through the array keeping track of the number of people alive at each point and the maximum number of people alive at any point (and the year(s) thereof). O(P log P) (from the sort), no explicit dependance on R. Are there any other good solutions? I cannot imagine that there would be anything that's sublinear in P, so about the only other thing I could imagine would be something that is linear in P and sublinear in R.
  - gaylemcd 11y ago
    Yes, that's another good solution. You can't really compare O(P + R) and O(P log P). Of course, you could argue that P could grow a lot faster than R, so O(P + R) would be better. That's probably true in a "real world" sense, but not in a mathematical sense.

dlandis 11y ago

In my experience after reading her book and some of her articles I think Gayle (and many other interviewers) underestimates the effect nerves have on certain people. She may be a little too quick to classify certain people as "dumb" when, in fact, some people's brains just totally freeze up during traditional coding interviews. I suspect more outgoing, extroverted people have a hard time fathoming what that's like or even that it is possible.