Sumplete is Hard, Even with Two Different Numbers

Abstract: Sumplete is a logic puzzle famous for being developed by ChatGPT. The puzzle consists of a rectangular grid, with each cell containing a number. The player has to cross out some numbers such that the sum of uncrossed numbers in each row and column is equal to a given integer assigned to that row or column. In this paper, we prove that deciding solvability of a given Sumplete puzzle is NP-complete, even if the grid contains only two different numbers.