I like the lending library / coffee shop notion as well, and if you don't have a lot of runway to try this, you might be able to put out a signup sheet asking people to pre-commit to a multi-month membership up front - if there's not enough interest there to keep you afloat (or get you close), try something else. Should serve to at least get baseline validation on the concept before you sink any real time / money / effort into it.
Unless I'm misreading the question, it's actually a good deal trickier than FizzBuzz - the difficult part isn't computing the "sustainability scores" from the input strings, but in maximizing the combination of product offers across the set of offers and customers. It's actually analogous to a rather well studied combinatorial optimization problem (that I won't call out by name here so as to avoid letting potential job applicants look up the answer too easily) that has a fairly non-obvious pseudo-polynomial time dynamic programming solution. The naive solution is exponential time (and still a bit tricky for a novice). I suspect the intent of the question is to find applicants that give the optimal solution rather than the naive one (and to weed out applicants that can't give any correct solution), but I could be mistaken.
I think the issue we're all having stems from the structural redesign of opencv 2.2. Everything has been split up into smaller headers, and the functionality is similarly separated into different shared libraries. It's a more logical code structure, but it means that we need to have different makefile rules for pre-2.2 and 2.2+ code.
As far as -lhighgui -lcv -lcxcore is concerned, those libraries don't exist on my machine anymore. "highgui" is "/usr/lib/libopencv_highgui.so", and so on. That would explain why my 'fix' didn't work for you.
The concept is great. Love the low friction of the free form input as well as the public/private dichotomy.
One minor bug I encountered: If I enter "I like #foo" and save it, it is filed under the tag #foo. If I then edit that item to be "I like #food" it stays filed under it's original tag, #foo, rather than being moved to #food.