06.03.2010, 19:20
My starting point for Kit Kat was:
A can be neither directly above C (because the 22 would carry over) nor directly below C (the combination of 1111 and 4 becomes impossible). Similarly, A can't be directly above B (because of the 4) or directly below B (1111 and 12). Therefore, A must be either top or bottom grid, with D directly below/above it.
When I guessed correctly that holes in the bottom grid can't be painted black (I should have asked before, but forgot), the puzzle was no more difficult.
Distiller, however, was a lot of trial and error for me.
A can be neither directly above C (because the 22 would carry over) nor directly below C (the combination of 1111 and 4 becomes impossible). Similarly, A can't be directly above B (because of the 4) or directly below B (1111 and 12). Therefore, A must be either top or bottom grid, with D directly below/above it.
When I guessed correctly that holes in the bottom grid can't be painted black (I should have asked before, but forgot), the puzzle was no more difficult.
Distiller, however, was a lot of trial and error for me.