We can now decide on all of the highlighted cells.
- The wall with 4 blocks must expand in to the highlighted
cells as there is nowhere else for it to expand in to. We can also surround this wall with
- The cell on the left handside must be blue, as there isn't a wall that can reach it. The wall with
7 cells is long enough to reach it, but in doing so it wouldn't give the '3' enough space to expand in
- The cell at the bottom must be a wall, otherwise you would have a 2x2 block of blue cells, which
is against rule 6.
- The remaining highlighted cell on the right must be blue, as there is no wall that can reach it.