[microsage]

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.