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Tech-Interview Riddles
An anonymous submitter writes "A computer engineering student at UC Berkeley has made a comprehensive archive of riddles from technical interviews. Very challenging and loads of fun. Also useful for interview preparation."
What's up with using this type of question for interviews, anyway? Sure, they can be fun, but they're perfectly useless as far as telling whether someone can actually write solid code. 9 times out of 10, all they tell you is whether the interviewee has heard that one before.
To interviewers: Do you really think that the answers to these questions don't spread through the entire department within 15 minutes after your first interview? I realize that "knowing the answer" makes you feel smarter than the prospective employee in some sense, but how about actually doing your job for a change?
Am I the only one who thinks this interviewing technique is retarded?
Because Microsoft does something most definitely isn't a reason to emulate it. Microsoft isn't exactly known for producing well designed software, nor software that reuses proven patterns or algorithms that solved known problems 20 years ago. Better to hire a bunch of 21 year old college grads who can solve word problems from 8th grade algebra, and pretend that Microsoft invented computers! Whee.
When I hire developers I want them to be good developers, not promising young interns. My interview questions typically involve technology questions, process questions, some theoretical PROGRAMMING questions, and some social / communication questions. I'm not saying that hiring smart people is a bad idea, but ignoring skills and only looking at generic problem solving ability is a recipe for unbelievably bad code. It's like hiring musicians based on measured hearing sensitivity and reflexes. OK, maybe that matters if you want to figure out which 5 year old is going to be a prodigy, but hand them an instrument and the noise that comes out is going to sound like ASS.
Examples of things that "smart" developers I've worked with before have totally missed:
- the existence of more efficient data structures than arrays
- generalizing code into reusable chunks (functions, objects, whatever)
- regular expressions
- the difference between "client" and "server"
- the reason for using descriptive variable names
- collection libraries with built in sorting ("whatcha workin' on?" / "coding up a quicksort algorithm" / "in a J2EE app!?!?")
You can't just get this from reading a book, either, although that definitely helps. You have to have some degree of EXPERIENCE too: at least a few projects, and some awareness of things like performance tuning, security, coding for maintainability, etc.
I would use these "tech interview questions" only for hiring interns or recent college grads where the expectation is zero experience, zero clue, zero skill, and a correspondingly low salary. After all you're investing in someone. But for someone that commands a market rate developer salary in the high five figures, screw the brain teasers - just spend a couple of hours grilling them on skills, experience, discipline, etc. They will respect you big time in return because they know when you extend an offer that they won't be working with a bunch of dumb-asses who can get the explorers across the river without being eaten by the headhunters but who can't code their way out of a soggy paper bag.
I've caught some really bright people with it.
So, what's the point again? Proving people aren't as bright as they think? Making people sit there and squirm because they really need a job, are nervous anyway, and have some "three cups and a white marble" puzzle standing between them and feeding their kids?
I don't get it. My first question would be "why don't we just hire the bright people and get back to work?"