CareerCup

since everybody can do above, I will just write the prove :-)
prove by induction: base case ''; '(' ')'
which class of grammair: you can write a BNF production like
programm = {expression}
expression = "(" expression ")" | "(" ")"

{prodcution} means n-times, where 0<=n
2nd prove, just write a dump parser like a LL1 or recursive descent

so it's at most a context free language, question is if its a regular grammar as well (finite automata) ... it's too long, but I think a regular automata can't parse it (not to be confused with modern regular expressions...) could somebone comment on the last please.

You are almost right Chris brackets matching are not regular.
They are (Non deterministic) Context Free at best.

And yea I give n take interviews fairly regularly.
Appeared for : 50+ , Taken : 600+. There were days where I used to take 10 interviews a day, and there are days where I used to appear for 3 full panel interview a day. It is a fun activity.