4 ms·

It's impossible to get real insight from them, because you can't differentiate between those who worked it out, and those who have read about it. The fact tha

by ori_b 14y ago

It's impossible to get real insight from them, because you can't differentiate between those who worked it out, and those who have read about it. The fact that they're involved enough in the industry to know about fizzbuzz is still a strong signal. It will only come up if participate in some sort of developer community, which, I suspect, is something that the completely incompetent don't do, as a rule. Once again, it's not designed to find the top talent. It's merely a high pass filter that removes the hopeless from the set of people to consider. But even if fizzbuzz is something that the hopeless start learning by rote, switching it out for any other trivial problem will still work. "Count the number of 'a's that come after 'g's in a string", "print the lyrics to 99 bottles of beer", or hundreds of other problems like that are just fine for the task.

grey-area 14y ago
Once again, it's not designed to find the top talent. It's merely a high pass filter that removes the hopeless from the set of people to consider. I'm sure it is useful in some situations, particularly in big companies with a broken hiring process. I imagine 37Signals don't find it useful as they have a more effective screening process, and people coming to interview simply couldn't possibly be that bad as they're referred or they've seen some code they wrote. If you are really faced with candidates who are incompetent (i.e. HR has filtered candidates for you based on CVs or similar), I think I'd try to automate some kind of online quiz they can go and take before they're even allowed to apply (which can include fizzbuzz or whatever little puzzles you want, checks for cheating etc) - then you can spend the phone screen or interview actually talking about interesting stuff which is in the problem domain they'll actually be tackling and finding out what they'd do with it. I just suspect these questions can be gamed and are not necessarily weeding out all the undesirables, just those who haven't done any homework on your hiring process. I've seen people hired who talked a good game and could have passed these trivial tests without giving away that they'd just read up on likely ones, but were lacking in all the skills necessary to bring projects in on time and competently - that sort of mediocre candidate who lies about experience and knows the basics is far harder to stop. It's interesting how different people react to IQ tests or little programming tests though - some people hate the implication of jumping through hoops, and that ability/knowledge can be reduced to such simple set of tests, and resent being subjected to them. Others really don't care and find them interesting or at worst trivial. I'd find it kind of weird trying to guess in an interview if someone who asks for say 'select the second highest number in this list' just wants a quick solution like list.sort[list.count-2] (which in the real world would be the first choice until or unless you are likely to hit major performance issues), or if they want you to write a trivial sorting algorithm for them and explain that you're familiar with the content of an undergraduate CS course. It's also interesting seeing the range of different interview questions posted here as examples - some are trivial filters as you say, some are more involved, and some require knowledge of basic undergrad stuff, so I'm not completely sure that all of these puzzles are intended as completely trivial, there's always the temptation to elaborate them into some kind of exam (like those posted on HN a while back with maths questions) for esoteric knowledge which is frankly useless in most people's job.
- bearmf 14y ago
  'select the second highest number in this list' is actually O(n) and does not require sorting.
  - grey-area 14y ago
    Does that mean I fail the test :) A sort then select for the second highest seemed the simplest solution off the cuff (perhaps not the quickest), and if the code is fast enough, there's no point in optimising. Of course you could write a loop and check each value against a stored memo - your O(n) right?, but why bother when the library sort is fast enough for the purpose? If you're dealing with genuinely huge data sets obviously this becomes important, but then often the data will be in a db anyway.
    - bearmf 14y ago
      It depends entirely on the person asking the question. Some people probably don't care, but there are some fans of the most efficient possible solution.
    - danielweber 14y ago
      As the person who posted that question, if you gave me that answer right away, I'd say "good, but can you do better?" "Sort and take the second highest" is a fine first answer. I'd expect most good candidates to start with that. I'd also expect them to say "but I think I can do better" on their own.
      - grey-area 14y ago
        This is where I find questions like this a little confusing. To define better (at least in real world situations) the question requires more context. How many records? How are they stored? What are the characteristics of the storage? Which libraries are we using to store it and how do they behave (and in the real world there might be a few)? What are the other constraints? If we request a sort (say in a remote db) will that be quicker than the latency of requesting data in batches and iterating? Presumably you mean better given infinite memory to store all the records and a very large number of records? Because for most small collections of say a few thousand, a sort then select would be better than an iteration IMHO as it is simpler and the intent is clear if performance is acceptable. Perhaps I have misunderstood the intent of the question though, I'd be interested to hear what you feel is the ideal answer.
matwood 14y ago
It will only come up if participate in some sort of developer community, which, I suspect, is something that the completely incompetent don't do, as a rule. A great thing a small company can do to find people is sponsor a users group of some sort. If your company does Java start a JUG, Ruby start a RUG, etc... For the price of some pizza you can informally meet people that by the nature of showing up give a strong signal as people you may want to talk to when looking for your next employee.

by ori_b 14y ago

grey-area 14y ago

Once again, it's not designed to find the top talent. It's merely a high pass filter that removes the hopeless from the set of people to consider. I'm sure it is useful in some situations, particularly in big companies with a broken hiring process. I imagine 37Signals don't find it useful as they have a more effective screening process, and people coming to interview simply couldn't possibly be that bad as they're referred or they've seen some code they wrote. If you are really faced with candidates who are incompetent (i.e. HR has filtered candidates for you based on CVs or similar), I think I'd try to automate some kind of online quiz they can go and take before they're even allowed to apply (which can include fizzbuzz or whatever little puzzles you want, checks for cheating etc) - then you can spend the phone screen or interview actually talking about interesting stuff which is in the problem domain they'll actually be tackling and finding out what they'd do with it. I just suspect these questions can be gamed and are not necessarily weeding out all the undesirables, just those who haven't done any homework on your hiring process. I've seen people hired who talked a good game and could have passed these trivial tests without giving away that they'd just read up on likely ones, but were lacking in all the skills necessary to bring projects in on time and competently - that sort of mediocre candidate who lies about experience and knows the basics is far harder to stop. It's interesting how different people react to IQ tests or little programming tests though - some people hate the implication of jumping through hoops, and that ability/knowledge can be reduced to such simple set of tests, and resent being subjected to them. Others really don't care and find them interesting or at worst trivial. I'd find it kind of weird trying to guess in an interview if someone who asks for say 'select the second highest number in this list' just wants a quick solution like list.sort[list.count-2] (which in the real world would be the first choice until or unless you are likely to hit major performance issues), or if they want you to write a trivial sorting algorithm for them and explain that you're familiar with the content of an undergraduate CS course. It's also interesting seeing the range of different interview questions posted here as examples - some are trivial filters as you say, some are more involved, and some require knowledge of basic undergrad stuff, so I'm not completely sure that all of these puzzles are intended as completely trivial, there's always the temptation to elaborate them into some kind of exam (like those posted on HN a while back with maths questions) for esoteric knowledge which is frankly useless in most people's job.

bearmf 14y ago
'select the second highest number in this list' is actually O(n) and does not require sorting.
- grey-area 14y ago
  Does that mean I fail the test :) A sort then select for the second highest seemed the simplest solution off the cuff (perhaps not the quickest), and if the code is fast enough, there's no point in optimising. Of course you could write a loop and check each value against a stored memo - your O(n) right?, but why bother when the library sort is fast enough for the purpose? If you're dealing with genuinely huge data sets obviously this becomes important, but then often the data will be in a db anyway.
  - bearmf 14y ago
    It depends entirely on the person asking the question. Some people probably don't care, but there are some fans of the most efficient possible solution.
  - danielweber 14y ago
    As the person who posted that question, if you gave me that answer right away, I'd say "good, but can you do better?" "Sort and take the second highest" is a fine first answer. I'd expect most good candidates to start with that. I'd also expect them to say "but I think I can do better" on their own.
    - grey-area 14y ago
      This is where I find questions like this a little confusing. To define better (at least in real world situations) the question requires more context. How many records? How are they stored? What are the characteristics of the storage? Which libraries are we using to store it and how do they behave (and in the real world there might be a few)? What are the other constraints? If we request a sort (say in a remote db) will that be quicker than the latency of requesting data in batches and iterating? Presumably you mean better given infinite memory to store all the records and a very large number of records? Because for most small collections of say a few thousand, a sort then select would be better than an iteration IMHO as it is simpler and the intent is clear if performance is acceptable. Perhaps I have misunderstood the intent of the question though, I'd be interested to hear what you feel is the ideal answer.

matwood 14y ago

It will only come up if participate in some sort of developer community, which, I suspect, is something that the completely incompetent don't do, as a rule. A great thing a small company can do to find people is sponsor a users group of some sort. If your company does Java start a JUG, Ruby start a RUG, etc... For the price of some pizza you can informally meet people that by the nature of showing up give a strong signal as people you may want to talk to when looking for your next employee.