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Simple Colouring
Colour a digit's conjugate pairs in two alternating colours. If two cells of the same colour share a house, that colour is impossible — so the digit is removed from every cell of that colour.
There's a move in the grid.
Colour a digit's conjugate pairs in two alternating colours. If two cells of the same colour share a house, that colour is impossible — so the digit is removed from every cell of that colour.
There's a move in the grid.