Most likely because he/she uses all the hints, I'm just using 2 of them. With all of the hints the solving is much easier of course...
I actually solved it without hints first, then there are multiple solutions, which are `pinned down' by supplying two hints.
That code might have been inspired by mine--which is fine---as some of the choices are really similar and also the exact same options, in the same order, method is exactly the same. Code is just been rewritten in places Plus@@... instead of Total@..., and similar small changes. Especially the last line:
BarcodeRecognize[(1 - constraintTable) // Image]
gives it away... Could've been BarcodeRecognize@Image[1-constraintTable] or such, but no exactly like mine ;-)
