[fenomas]

> at which point you can really only evaluate all possible combinations

You only need one counterexample, and in this case you can easily find it. E.g., you can note that the duckie in GP's solution can be swapped for the pinwheel+whistle without changing the solution's total cost, ergo the solution isn't unique.

I think a lot of people are looking at this like a coding interview, where it's assumed that your algorithm must work for all possible inputs, rather than just the inputs stated.

[scrollaway]

It’s easy to understand how a student at this level would approach it and give an answer.

Everybody’s problem here, mine included, is that this is a toxic way to teach math. One which has no use in math, which does not teach how to properly approach a problem and which in fact teaches and artificially rewards a bad approach: “just try it! It’ll work because all problems, even ridiculously difficult ones, are artificially customised to be easy for you to solve!”.

It’s bad. It’s awful. It’s not good. It’s everything math education shouldn’t be: boring, artificial, useless, constrained and a lie.

I don’t want children to solve this problem. I want children who can like math, to like and learn math. This is one of many drops in the jar of bullshit that will eventually overflow and turn them off.