Why we don't hire programmers based on puzzles and tricks

Post by rgovind » Fri, Feb 22, 2013, 7:54 PM UTC

trotsky wrote: post #202

cletus wrote: post #44

Sigh. This is the issue that will just never die. Let's just summarize the points: - Not everyone can produce real-world code. Most of what we do for a living belongs to our employer. Side projects, particularly in the US, can be an issue for IP reasons (California is somewhat of an exception here); - Side projects, even open source projects, can be of questionable "real world" value; - I've personally encountered ma…

One thing you're testing for is how well their brain works with an excess of adrenaline floating around in their body. All of the best interviewers I've known take great pains to make the interviewer feel comfortable and chatty - after all, they aren't going to be filled with interview anxiety when they're actually working there. A minority of your applicants are going to perform badly in that situation because the a…

Post by freework » Fri, Feb 22, 2013, 7:58 PM UTC

mattstreet wrote: post #220

freework wrote: post #163

I've been interviewing pretty much non-stop since last April. I feel like I've become somewhat of an expert when it comes to interviewing processes. First off, as I've become a better programmer, I feel this fact is best shown in my opinions. When I first started out, if you had asked me my opinion of PHP vs Python, I would not have been able to say anything coherent. Now that I've worked with both technologies, my o…

I think you're wrong about the 100% bad place to work just because someone asked you to reverse a string without using library functions. I would think your computer science education would have prepared you to plan out such an algorithm. Sadly, its pretty had for a place to confirm you have subconscious skills by asking a question and then waiting for you to come back the next day with the answer once it popped into…

Post by freework » Fri, Feb 22, 2013, 8:01 PM UTC

kragen wrote: post #250

freework wrote: post #163

I've been interviewing pretty much non-stop since last April. I feel like I've become somewhat of an expert when it comes to interviewing processes. First off, as I've become a better programmer, I feel this fact is best shown in my opinions. When I first started out, if you had asked me my opinion of PHP vs Python, I would not have been able to say anything coherent. Now that I've worked with both technologies, my o…

You mean ' '.join(the_string.split()[::-1]). Which is a totally reasonable thing to do, but doesn't exercise the same kind of thinking as doing it letter by letter. Can you solve it letter by letter, even now that you're not in an interview?

Post by michaelfairley » Fri, Feb 22, 2013, 8:03 PM UTC

steveklabnik wrote: post #265

zeteo wrote: post #263

Earlier quoted context omitted.

Come to think of it, swapping two variables in place is a horrible question - because you can't really do it! A statement like a = a + b requires the (invisible) presence of a register where a + b (or xor or whatever) is placed right before being written back to a. But then you might as well use this register directly for the swap instead of dabbling around with one-to-one functions.

Also, it depends on which language you're using... $ irb irb(main):001:0> a = 1 => 1 irb(main):002:0> b = 2 => 2 irb(main):003:0> b, a = a, b => [1, 2] irb(main):004:0> puts "#{a} #{b}" 2 1 => nil (obviously this has the same flaw you mention, the interpreter is doing stuff for you. It follows the letter of the 'no intermediate variables' only.)

  a ^= b
  b ^= a
  a ^= b

Post by GhotiFish » Fri, Feb 22, 2013, 8:09 PM UTC

AdamTReineke wrote: post #130

potatolicious wrote: post #12

Damn right. Even worse than whiteboarding random algorithms are logic puzzles. I can sort of see how implementing my own hash table fits into a dev job, but I why manhole covers are round, or light bulbs in a room has absolutely nothing to do with anything relevant in our field. People who use logic puzzles as proxies for anything in an interview have my everlasting scorn.

My all-time favorite interview was one when I was interviewing for an SDET intern position at Microsoft. That interview (one in a day of four interviews) featured a great progression: logic puzzle, code the fixed input solution, code the n input solution, test your solution. The puzzle was (apologies to the interviewer, but it IS a common puzzle) the eight ball and balance problem, where one ball is heavier than the…