ref: 420663d47790a7e34a1662d679a0c00efdb5b7e5
dir: /html/range.html/
Range <p> Colour some squares black, so as to meet the following conditions: <ul> <li> No two black squares are orthogonally adjacent. <li> No group of white squares is separated from the rest of the grid by black squares. <li> Each numbered cell can see precisely that many white squares in total by looking in all four orthogonal directions, counting itself. (Black squares block the view. So, for example, a 2 clue must be adjacent to three black squares or grid edges, and in the fourth direction there must be one white square and then a black one beyond it.) </ul> <p> Left-click to colour a square black. Right-click to mark a square with a dot, if you know it should not be black.