quwiltw

I have been using a particular question when interviewing developers for a while now and I've just been told that it's too hard a question. I totally disagree and think it's a basic concept that everyone should understand and be able to answer relatively quickly. Do you think it's unfair to expect an applicant for a Junior Software Engineer to do the following?

Implement a function accepting n and returning n! and it must be implemented recursively.

(It's not supposed to be an 8th grade math test so I willingly provide the definition of n! and provide 0! to 5! as examples to eliminate potential embarrassment.)

All I'm attempting to do is see if they can actually program and if they understand the concept of recursion. Anyone think this is an unfair expectation for a Junior Software Engineer? (Most are straight out of 4 years of college)

lebb

That sounds perfectly reasonable to me, and is in fact quite a bit simpler than the programming challenges I have been given in interviews.

quwiltw

Thanks lebb, his main complaint was the demand of implementing it recursively. I've been trying to think of another non-recursive question, but it's difficult to find something that's sufficiently hard enough to make sure they can actually program but sufficiently easy enough so that they aren't sitting in my office for two hours trying to figure it out. If you've got any suggestions that are a good balance between the two I'd love to hear them.

Memnoch1207

I think the question is fine, it may be the way you phrase the question to the applicant, that gets them confused?

after all a recursive function is just a function that keeps calling it self (looping) until a condition is met. I would think that these college graduates would know this, but maybe not!

BillSoo

Much as I like recursion, you don't see too much of it outside of school. In production environments, the possible problem of a "stack overflow" reduces it's utility.

I wrote a simple function in Tutors Corner that might do the trick...

The title is "Recursively searching a Directory" but that code was lost in the forum shuffle. Instead, I had a NON-recursive version. You can ask them to write something like that:
http://www.xtremevbtalk.com/show...6990#post16990

quwiltw

My wording is intentional. In the interview, my desire is not to teach recursion, but to tell them how I want it implemented and see if they understand. For example, if I wanted them to solve the problem with counter controlled loop, I wouldn't want to explain what a counter-controlled loop is.

quwiltw

Thanks BillSoo, I do have that internal debate. It's kinda contradictory I suppose, in that, if they were ever required to implement n! "by hand" I'd be pretty ****ed if they implemented it recursively. On the other hand, asking them to traverse a BST is a bit more than I want to wait for in an interview. I just think it's a nice clean problem, that's relatively easy to implement.

Thinker

I agree it is a reasonable question, difficulty-wise, but my opinion
is recursion is only useful in specialized situations. By using a
question like this you might be implying that you expect
programmers to use it anytime it could be used, most of which
would create slower, more inefficient code. Now if this is just one
of many questions, and they otherwise get all the other ones
correct, you might still consider them for a junior position on the
condition they learn how (and when) to use recursion.

As to an alternate question, I think it should relate to the kind of
programming that they would normally be doing. For instance, if
the type of programming requires alot of string manipulation, then
a function that receives a string (and possibly some other params)
and returns a substring (making use of InStr, Mid$, etc.). If the
main programming is numeric calculation based, make the correct
function very dependent on proper variable types, including them
having to select the right types for the size and precision of the
params and result you need. If database programming is involved
make sure they have a clue about using SQL.

Robert Neilson

i dont see anything wrong with it and i am by no means qualified as a programmer

Robby

I was interviewed last week, 50 questions, most all were theory (very advanced) and very few had code.

I wish there was more coding on the quiz simular to yours (quwiltw)

Mill

I think that the question is fine, but I agree with Bill and Thinker that recursion is mostly just used in college. Plus, if you don't want them to use recursion while they're actually working for you, it seems a bit odd.

You could ask them to write some somewhat simple procedures, such as:[list=1][*]Write a function that takes a string as a parameter and returns the reverse of the string.[*]Write a function that takes a string as a parameter and determines if it is a (sorry, brain-freeze)... if the word reads the same forward and backward.[*]Write a simple encryption or sorting algorithm.[/list=1]

quwiltw

I didn't say that. I said I wouldn't want them to implement n! recursively. I *would* want them to know when a recursive solution was appropriate. There are a number of cases, such as when the data structure is naturally recursive (ex. tree-like) where it's a obvious fit. As I said, the only reason I use n! in my test is because it's simple, clean, and quick. Asking an applicant to do a traversal of an AVL tree (something more realistic) using recursion is a bit too much for an interview methinks.

BTW, It's called a palindrome and I like that one, I think I'll use it.


Thanks,

Mill

Thanks. It's been one of those days. LOL

If you want to make sure that they know about the concept of recursion, then I think it's an excellent question because it covers the most basic aspects of recursion (what to do in your base case, what to do otherwise) without needing a whole lot of extra brainpower.

John

That is what I was thinking, similar to our recent palindromes contest.

Orbity

Mill

Exactly. It's bad to have a Monday kind of morning on a Tuesday.