4 ms·

It might be an incredibly common interview question, but it's not an incredibly common day-to-day task, particularly when there are methods built in to classes

by mmorett 14y ago

It might be an incredibly common interview question, but it's not an incredibly common day-to-day task, particularly when there are methods built in to classes that perform this function. An interesting task? Perhaps. But not reflection of the dev's skills, per se. You're not asking about syntax with this. It's a problem solving question and at the end of the day, the only real metric here is not whether a dev could code this up, but whether he can code it up quickly, under time constraints, while being stared at, under pressure, with rent or a mortgage on the line, and maybe kids to feed. I am hard pressed to think of even one real life dev task I had in my entire career where I had to solve a problem under those circumstances. For most devs, we take ownership of the problem and solve it at our desk under reasonable time frames without the spotlight. For bigger problems, we might think about it in the car on the way home. We might sleep on it over the weekend. That doesn't apply to reversing a string, of course. But you have to consider that, depending on the dev's background and skills, he may be spending time in jQuery, maybe Spring and Hibernate (for Java guys), maybe even some CSS. Maybe he's a GWT guy? Maybe he was assigned to a team dedicated to (God forbid) EJBs. In other words, he may be multifaceted and spends more time working with an API than "just" raw language coding. The language is just a means for working with the API. And the one thing you want to measure is not something he does daily. Now, if he can't use a for loop, feel free to mock him. But reversing a string? That's clearly a puzzle. EDIT: I can't get this part out of my mind: "Is incredible how badly the test goes with the people! I interview for myself or others more than 100 people (of any background, including university, tech schols...) and I think only 10/12 people do it correctly - barely-" So you continue to use that question? Despite the results? So that when you do hire a guy that passes, he won't ever do this on the job because you know you damn well he should use the reverse() method? Because you won't pay him to code it raw and waste time and money when there is a 1.5 second solution to this? That's sadistic. :-)

suresk 14y ago
I don't see how reversing a string is a "puzzle" - I'd put its difficulty on par (or maybe slightly harder than) fizzbuzz. In most mainstream languages, it requires 2 pieces of knowledge: 1) That a string is implemented as an array of characters. 2) How to reverse an array. The implementation is straightforward and should be trivial for just about anyone who's done much development. I don't know that the question is that great, but it certainly isn't bad as a fizzbuzz-type question to use as a filter.
- mmorett 14y ago
  Fair enough. Here's my solution: def reverse() { def a = "Can a fella get a job?" StringBuilder b = new StringBuilder() for (int i = a.length(); i > 0; i--) { b.append(a.charAt(i-1)) } print b.toString() } But it doesn't use arrays because quite frankly, I haven't used an array in years. I despise the noise of the brackets. :-) Seriously, I use ArrayLists instead of arrays. But even on this FizzBuzz lite exercise, I got tripped up. My "i > 0" was off by one. And I started down the path of a.substring, but that was a bad move. I quickly switched to charAt. But about the only relevant piece of this: on an IDE, I was able to place a breakpoint, see where I'm at, what my variables look like, and make adjustments. That's real life. My original cut of this would have disqualified me. Actually, even the cut above would disqualify me since I didn't use arrays. But I need to confess. What you see above is literally the first time I've ever reversed a string in this manner. It's just not something I do. And it didn't roll off the tongue so to speak. I knew I had to process the string from the end and work backwards, but it still felt like trivia and not a substantive inquisition into my skills or experience. Trivial? A bit. It took me about 5 min. The off by one was killing me. It hits you in two places: the i > 0 and the charAt(i-1).
  - suresk 14y ago
    That isn't a bad solution. You obviously hope that someone you're interviewing can come up with something like that fairly quickly, but I certainly wouldn't disqualify you based on your method of solving it or an initial off-by-one error. > What you see above is literally the first time I've ever reversed a string in this manner. It's just not something I do. There is a certain amount of value in that - seeing how someone reacts to and solves something they've never seen before. Can you come up with a reasonable plan for attacking the problem, implement it, test it to see if it works in a bunch of cases, and make the necessary adjustments? To be fair, the coding you do in an interview is a bit artificial - the problems may not be typical and you are without the environment you are usually coding in. The good news is that it is a skill that you can work on and become better at, and it is usually worth doing so if you are pursuing a job and you know these kinds of things will come up. I don't think it is wasted effort either - I've been trying to work on my algorithm/data structure skills by solving interview-type problems, and I've noticed that the work I've been doing to learn to solve them better has been beneficial in my daily programming as well.
mamcx 14y ago
> So you continue to use that question? Well, yes. Is the most simple one I can think that show if a person can declare variables, do a loop and show the result. If exist something better, I wanna know! Before that question, I do things more complicated. Like do some CRUD, or some kind of task that was realted to the company I was before. But my first results with that lead me to simplify the interview a lot (in time and questions) because I see that if a person can't do this kind of task is pointless try with something better. And I don't do much presure. I let them alone and give them all the time they want, with internet acces and that. I continue doing my work while they complete the task. Is important to understand that in my past companies I was tasked to interview fresh graduated coders, and for a lot of backgrounds. And they pay badly. So no much oportunity of get "top players" back them. However, I interview several people with (in theory) experience or from reputable universities and that not change at all the end results. P.D: Some point to the complications of do this task properly (because unicode). I don't even expect that kind of depth in the answer, looking more in the basic skill, code formatting, and the ability to explain the code writed...

by mmorett 14y ago

suresk 14y ago

I don't see how reversing a string is a "puzzle" - I'd put its difficulty on par (or maybe slightly harder than) fizzbuzz. In most mainstream languages, it requires 2 pieces of knowledge: 1) That a string is implemented as an array of characters. 2) How to reverse an array. The implementation is straightforward and should be trivial for just about anyone who's done much development. I don't know that the question is that great, but it certainly isn't bad as a fizzbuzz-type question to use as a filter.

mmorett 14y ago
Fair enough. Here's my solution: def reverse() { def a = "Can a fella get a job?" StringBuilder b = new StringBuilder() for (int i = a.length(); i > 0; i--) { b.append(a.charAt(i-1)) } print b.toString() } But it doesn't use arrays because quite frankly, I haven't used an array in years. I despise the noise of the brackets. :-) Seriously, I use ArrayLists instead of arrays. But even on this FizzBuzz lite exercise, I got tripped up. My "i > 0" was off by one. And I started down the path of a.substring, but that was a bad move. I quickly switched to charAt. But about the only relevant piece of this: on an IDE, I was able to place a breakpoint, see where I'm at, what my variables look like, and make adjustments. That's real life. My original cut of this would have disqualified me. Actually, even the cut above would disqualify me since I didn't use arrays. But I need to confess. What you see above is literally the first time I've ever reversed a string in this manner. It's just not something I do. And it didn't roll off the tongue so to speak. I knew I had to process the string from the end and work backwards, but it still felt like trivia and not a substantive inquisition into my skills or experience. Trivial? A bit. It took me about 5 min. The off by one was killing me. It hits you in two places: the i > 0 and the charAt(i-1).
- suresk 14y ago
  That isn't a bad solution. You obviously hope that someone you're interviewing can come up with something like that fairly quickly, but I certainly wouldn't disqualify you based on your method of solving it or an initial off-by-one error. > What you see above is literally the first time I've ever reversed a string in this manner. It's just not something I do. There is a certain amount of value in that - seeing how someone reacts to and solves something they've never seen before. Can you come up with a reasonable plan for attacking the problem, implement it, test it to see if it works in a bunch of cases, and make the necessary adjustments? To be fair, the coding you do in an interview is a bit artificial - the problems may not be typical and you are without the environment you are usually coding in. The good news is that it is a skill that you can work on and become better at, and it is usually worth doing so if you are pursuing a job and you know these kinds of things will come up. I don't think it is wasted effort either - I've been trying to work on my algorithm/data structure skills by solving interview-type problems, and I've noticed that the work I've been doing to learn to solve them better has been beneficial in my daily programming as well.

mamcx 14y ago

> So you continue to use that question? Well, yes. Is the most simple one I can think that show if a person can declare variables, do a loop and show the result. If exist something better, I wanna know! Before that question, I do things more complicated. Like do some CRUD, or some kind of task that was realted to the company I was before. But my first results with that lead me to simplify the interview a lot (in time and questions) because I see that if a person can't do this kind of task is pointless try with something better. And I don't do much presure. I let them alone and give them all the time they want, with internet acces and that. I continue doing my work while they complete the task. Is important to understand that in my past companies I was tasked to interview fresh graduated coders, and for a lot of backgrounds. And they pay badly. So no much oportunity of get "top players" back them. However, I interview several people with (in theory) experience or from reputable universities and that not change at all the end results. P.D: Some point to the complications of do this task properly (because unicode). I don't even expect that kind of depth in the answer, looking more in the basic skill, code formatting, and the ability to explain the code writed...