Wataridori is NP-Complete
arXiv:2601.09345
Abstract
Wataridori is a pencil puzzle that involves drawing paths in a rectangular grid to connect circles into pairs while satisfying several constraints. In this paper, we prove that deciding whether a given Wataridori puzzle has a solution is NP-complete via a reduction from Numberlink, another pencil puzzle that has previously been proved NP-complete.