A Programming Job Interview Challenge #13 – Brackets

The thirteen post of the series of programming job interview challenge is out, Only 13 comments with answers were provided to job interview challenge #12. This is a small amount comparing to the previous challenges, but I realize and understand that it was language specific and not very trivial challenge…

Jason Kikel was the first one to solve the question, and here is his short answer:

UnmanagedClass is referencing an address on ManagedClass without pinning it. The ManagedClass instance needs to be pinned so the GC won’t move it to another location during a collection.

In other words, I didn’t use the _pin keyword when I allocated the managed class. The process of pinning a managed object, cause the Common Language Runtime (CLR) Garbage Collector (GC) not to relocate and move the object in memory. So, when we pass managed data to unmanaged code, pinning is necessary.

James Curran posted the solution in his blog – http://honestillusion.com/blogs/blog_0/archive/2008/07/16/dev102-s-challenge-12-managed-unmanaged.aspx.

Those are the other readers who provided a correct solution for last week challenge: befarino, leppie, Christof Jans and Jelle Hissink.

This Week Question:

Your input is a string which is composed from bracket characters. The allowed characters are:'(‘, ‘)’, ‘[‘. ‘]’, ‘{‘, ‘}’, ‘<‘ and ‘>’. Your mission is to determine whether the brackets structure is legal or not.

Example of a legal expression: “([](<{}>))”.

Example of an illegal expression: “({<)>}”.

Provide the most efficient, elegant and simple solution for that problem.I think that this is a well known problem but I am not sure, so excuse me if this week’s question is screwed.

Get updates by RSS to catch up with the next posts in this series and to get the correct answer for today’s question. As always you may post the solution in your blog or comment. Comments with answers will be approved only next week.