5 ms·

Phil, the point is who gives a flying f in production about anagrams. Noone has to deliver a meaningful abstraction in < an hour (or 15 minutes as a "simple" e

Phil, the point is who gives a flying f in production about anagrams. Noone has to deliver a meaningful abstraction in < an hour (or 15 minutes as a "simple" example of "puzzle" testing), and interviewing for that is truly ridiculous. You and others might find it meaningful but after two decades of development I really have to question those who do.

nl 13y ago
Like you - I've never needed to solve an anagram in production. I think many are missing the point. In an interview situation, the anagram problem gets the person to write some basic, naive code (ie, proves that can track loops) which I think we would both agree is reasonable. Then the interviewer gets you to look at how to improve it. Hopefully you'll notice that iterating over both strings isn't very efficient, and reason about ways to improve that. It's that reasoning process that is important, not the knowledge of how to write an anagram solver. To be fair, though - most programmers should be able to solve it with a couple of hints.
- philwelch 13y ago
  If anything, not being a real problem is a feature. Very few candidates will have ever actually had to solve anagram problems, so most candidates will be equally unfamiliar with the question, making it a fair measure of the candidate's ability to solve simple problems they haven't seen before. Here's an example of an interview question that doesn't have this feature: "How would you serialize a tree?" The Lisp programmers will get that one right away. Even people with a passing familiarity with XML will get it right away. You don't know if they would have been able to figure it out themselves, all you know is that they've seen serialized trees before.
  - nl 13y ago
    Tree serialization seems reasonable - basically you end up looking at tree walking algorithms and some recursion, right? (I can't remember the costs & benefits of depth first vs breadth first traversal, but I'm sure I'd work something out). OTOH, I was once asked to write a Sudoku solver in an interview. I'd never really solved a Sudoku myself at the time (although at least I knew how it worked), so I had to try and work out an approach to solving the puzzle as well as how to write the code. I found that pretty tough.
    - philwelch 13y ago
      Tree serialization is a reasonable question, but it's one where lots of people have already seen the solution, hence my mentions of Lisp and XML.
spacemanaki 13y ago
The purpose of a question like this, and of the classic FizzBuzz question, is to be a lightweight test of whether a candidate can actually write code or not. That's all. It provides a negative signal if they fall completely to get anywhere close, and nothing more. There are alternatives, you could ask them to explain a piece of code they wrote on their own before the interview, any piece of code would do. I suppose that could be gamed which is why most companies opt for FizzBuzz. Personally, once I started thinking about these kinds of questions like this, I had less issue with them. Interviewing people who failed to write FizzBuzz opened my eyes too.
mmorett 13y ago
Since a reply link isn't available for spacemanaki's comment, I'll stick it here: "The purpose of a question like this, and of the classic FizzBuzz question, is to be a lightweight test of whether a candidate can actually write code or not. That's all. It provides a negative signal if they fall completely to get anywhere close, and nothing more." I disagree. Vehemently. Provide me an email address and I'll mail you tons of code I've written. You cannot, cannot conclude with any accuracy that the inability to code up a method/function to check an anagram means that the person cannot write code. What you can conclude is that they cannot write up a method/function to check an anagram. You're making an assumption. If a = b and b = c, then a = c. That works in math class but not here. The test is not one of syntax or knowledge of the language but of knowledge of a specific problem. Some here have used the word "trick". I don't even need to go there. Once you have the answer to this anagram exercise, you can back into why it's a good question, what it supposedly shows, etc. At that point you're justifying the question and defending it. But you missed the entire point of the exercise: you're supposedly screening candidates for knowledge of a language and how they might have used it in their past experience, but letting it all come down to whether they solve your specific problem on the spot with all of Pamela's concerns about stress, etc. It's easier to ask about an anagram than to ask about a candidate's past and what they did on their projects. If not an anagram, there are others. There will always be "solve this now" rather than "tell me about..." That's just the game.
- philwelch 13y ago
  > You cannot, cannot conclude with any accuracy that the inability to code up a method/function to check an anagram means that the person cannot write code. What you can conclude is that they cannot write up a method/function to check an anagram. If you can't check an anagram given the definition of an anagram and the programming language of your choice, what problems can you solve? It's not a hard question and if you can't come up with a correct solution at all, I dare say you lack the ability to program.
- karlmdavis 13y ago
  So, I understand and am incredibly sympathetic to the stress problem some folks have. I also occasionally freeze up when put on the spot, though I fortunately tend to recover after a minute or so of verbal stumbling. That said, hiring quality engineers is HARD, and often ends up coming down to a numbers game. If I've got 100 applicants to go through and know (from past experience) that over 80% of them couldn't code their way out of a wet paper bag, then I need short, deterministic interview techniques that will identify those candidates who are actually worth my time. Thus: fizzbuzz. I've met lots of folks who talk a great game, have all kinds of experience listed on their resume, and yet somehow can't write up a linked list or fizzbuzz solution in any language. So, I accept that there will be some false negatives in order to more quickly narrow the focus down to those few rare folks that can actually code. It sucks: it isn't entirely fair to folks who struggle with stress/nerves, but I need a 5-15 minute litmus test that can be done remotely and I haven't found anything else more effective. Short of wasting everyone's time with take-home projects (which I often employ in later stages of the interview process), what other options are out there?
philwelch 13y ago
I really have to question those who find the question so difficult they would rather rationalize why they shouldn't have to answer it or handwave about how they can't possibly solve even simple programming problems in anywhere less than an hour.
- mmorett 13y ago
  HN seems to lack reply links in some messages so I need to answer you here. "If you can't check an anagram given the definition of an anagram and the programming language of your choice, what problems can you solve? It's not a hard question and if you can't come up with a correct solution at all, I dare say you lack the ability to program." Here's your anagrams checker tough guy: static boolean anagram(String word1, String word2) { char[] chars1 = word1.toCharArray(); char[] chars2 = word2.toCharArray(); Arrays.sort(chars1); Arrays.sort(chars2); return Arrays.equals(chars1, chars2); } I was speaking in the abstract, but you made it personal. Would you like me to build a search engine next?
  - philwelch 13y ago
    Reply links take longer to generate on HN as comment threads get deeper in order to deter people from losing their temper and flaming each other. In your case I would say that didn't quite work. My comment was not meant personally but as a general statement. If you had kept your composure and waited for the reply link to show up instead of flying off the handle about it and replying to an unrelated comment, perhaps we would be having a more productive conversation right now.
    - mmorett 13y ago
      Then please accept my apologies. I enjoyed the anagram thing as it forced me into looking into it.
  - RogerL 13y ago
    Okay, now make it faster. I'm not trying to be obnoxious, but your answer is not optimal. Which is not a big deal, and it would give us a chance to talk about ways of optimizing code. Sooner or later we'd figure out if you knew what a hash table is and how to use it (no real points off if you never really got, under the pressure of an interview, the hash table solution to this problem), how you would go about profiling code, how you might solve this if they weren't strings but social security numbers, and so on. It's a launching off point to more interesting discussions. At least that's how I'd use it in an interview. Before long we'd be talking about a, I dunno, search engine or something.

nl 13y ago

Like you - I've never needed to solve an anagram in production. I think many are missing the point. In an interview situation, the anagram problem gets the person to write some basic, naive code (ie, proves that can track loops) which I think we would both agree is reasonable. Then the interviewer gets you to look at how to improve it. Hopefully you'll notice that iterating over both strings isn't very efficient, and reason about ways to improve that. It's that reasoning process that is important, not the knowledge of how to write an anagram solver. To be fair, though - most programmers should be able to solve it with a couple of hints.

philwelch 13y ago
If anything, not being a real problem is a feature. Very few candidates will have ever actually had to solve anagram problems, so most candidates will be equally unfamiliar with the question, making it a fair measure of the candidate's ability to solve simple problems they haven't seen before. Here's an example of an interview question that doesn't have this feature: "How would you serialize a tree?" The Lisp programmers will get that one right away. Even people with a passing familiarity with XML will get it right away. You don't know if they would have been able to figure it out themselves, all you know is that they've seen serialized trees before.
- nl 13y ago
  Tree serialization seems reasonable - basically you end up looking at tree walking algorithms and some recursion, right? (I can't remember the costs & benefits of depth first vs breadth first traversal, but I'm sure I'd work something out). OTOH, I was once asked to write a Sudoku solver in an interview. I'd never really solved a Sudoku myself at the time (although at least I knew how it worked), so I had to try and work out an approach to solving the puzzle as well as how to write the code. I found that pretty tough.
  - philwelch 13y ago
    Tree serialization is a reasonable question, but it's one where lots of people have already seen the solution, hence my mentions of Lisp and XML.

spacemanaki 13y ago

The purpose of a question like this, and of the classic FizzBuzz question, is to be a lightweight test of whether a candidate can actually write code or not. That's all. It provides a negative signal if they fall completely to get anywhere close, and nothing more. There are alternatives, you could ask them to explain a piece of code they wrote on their own before the interview, any piece of code would do. I suppose that could be gamed which is why most companies opt for FizzBuzz. Personally, once I started thinking about these kinds of questions like this, I had less issue with them. Interviewing people who failed to write FizzBuzz opened my eyes too.

mmorett 13y ago

Since a reply link isn't available for spacemanaki's comment, I'll stick it here: "The purpose of a question like this, and of the classic FizzBuzz question, is to be a lightweight test of whether a candidate can actually write code or not. That's all. It provides a negative signal if they fall completely to get anywhere close, and nothing more." I disagree. Vehemently. Provide me an email address and I'll mail you tons of code I've written. You cannot, cannot conclude with any accuracy that the inability to code up a method/function to check an anagram means that the person cannot write code. What you can conclude is that they cannot write up a method/function to check an anagram. You're making an assumption. If a = b and b = c, then a = c. That works in math class but not here. The test is not one of syntax or knowledge of the language but of knowledge of a specific problem. Some here have used the word "trick". I don't even need to go there. Once you have the answer to this anagram exercise, you can back into why it's a good question, what it supposedly shows, etc. At that point you're justifying the question and defending it. But you missed the entire point of the exercise: you're supposedly screening candidates for knowledge of a language and how they might have used it in their past experience, but letting it all come down to whether they solve your specific problem on the spot with all of Pamela's concerns about stress, etc. It's easier to ask about an anagram than to ask about a candidate's past and what they did on their projects. If not an anagram, there are others. There will always be "solve this now" rather than "tell me about..." That's just the game.

philwelch 13y ago
> You cannot, cannot conclude with any accuracy that the inability to code up a method/function to check an anagram means that the person cannot write code. What you can conclude is that they cannot write up a method/function to check an anagram. If you can't check an anagram given the definition of an anagram and the programming language of your choice, what problems can you solve? It's not a hard question and if you can't come up with a correct solution at all, I dare say you lack the ability to program.
karlmdavis 13y ago
So, I understand and am incredibly sympathetic to the stress problem some folks have. I also occasionally freeze up when put on the spot, though I fortunately tend to recover after a minute or so of verbal stumbling. That said, hiring quality engineers is HARD, and often ends up coming down to a numbers game. If I've got 100 applicants to go through and know (from past experience) that over 80% of them couldn't code their way out of a wet paper bag, then I need short, deterministic interview techniques that will identify those candidates who are actually worth my time. Thus: fizzbuzz. I've met lots of folks who talk a great game, have all kinds of experience listed on their resume, and yet somehow can't write up a linked list or fizzbuzz solution in any language. So, I accept that there will be some false negatives in order to more quickly narrow the focus down to those few rare folks that can actually code. It sucks: it isn't entirely fair to folks who struggle with stress/nerves, but I need a 5-15 minute litmus test that can be done remotely and I haven't found anything else more effective. Short of wasting everyone's time with take-home projects (which I often employ in later stages of the interview process), what other options are out there?

philwelch 13y ago

I really have to question those who find the question so difficult they would rather rationalize why they shouldn't have to answer it or handwave about how they can't possibly solve even simple programming problems in anywhere less than an hour.

mmorett 13y ago
HN seems to lack reply links in some messages so I need to answer you here. "If you can't check an anagram given the definition of an anagram and the programming language of your choice, what problems can you solve? It's not a hard question and if you can't come up with a correct solution at all, I dare say you lack the ability to program." Here's your anagrams checker tough guy: static boolean anagram(String word1, String word2) { char[] chars1 = word1.toCharArray(); char[] chars2 = word2.toCharArray(); Arrays.sort(chars1); Arrays.sort(chars2); return Arrays.equals(chars1, chars2); } I was speaking in the abstract, but you made it personal. Would you like me to build a search engine next?
- philwelch 13y ago
  Reply links take longer to generate on HN as comment threads get deeper in order to deter people from losing their temper and flaming each other. In your case I would say that didn't quite work. My comment was not meant personally but as a general statement. If you had kept your composure and waited for the reply link to show up instead of flying off the handle about it and replying to an unrelated comment, perhaps we would be having a more productive conversation right now.
  - mmorett 13y ago
    Then please accept my apologies. I enjoyed the anagram thing as it forced me into looking into it.
- RogerL 13y ago
  Okay, now make it faster. I'm not trying to be obnoxious, but your answer is not optimal. Which is not a big deal, and it would give us a chance to talk about ways of optimizing code. Sooner or later we'd figure out if you knew what a hash table is and how to use it (no real points off if you never really got, under the pressure of an interview, the hash table solution to this problem), how you would go about profiling code, how you might solve this if they weren't strings but social security numbers, and so on. It's a launching off point to more interesting discussions. At least that's how I'd use it in an interview. Before long we'd be talking about a, I dunno, search engine or something.