I want to recurse several directories and find duplicate files between the n number of directories.

My knee-jerk idea at this is to have a global hashtable or some other data structure to hold each file I find; then check each subsequent file to determine if it's in the "master" list of files. Obviously, I don't think this would be very efficient and the "there's got to be a better way!" keeps ringing in my brain.

Any advice on a better way to handle this situation would be appreciated.