Minimum exact cover of grid with squares; extra cuts
问题 This problem appeared in a challenge, but since it is now closed it should be OK to ask about it. The problem (not this question itself, this is just background information) can be visually described like this, borrowing their own image: I chose to solve it optimally. That's probably (for the decision variant) an NP-complete problem (it's certainly in NP, and it smells like an exact cover, though I haven't proven that a general exact cover problem can be reduced to it), but that's fine, it