For every cell that was marked to begin with, if it is adjacent to two or three marked squares, mark it with another horizontal line about two-fifths of the way down in the square.

For every unmarked cell, mark it with a line if exactly three of the adjacent grid elements are marked.

Repeat with lines horizontal lines three-fifths of the way down, based on the previous lines.

Continue for a total of twenty sets of lines: The fifth set of lines will be at the bottom of the squares. For the sixth set of lines, mark vertical lines one-fifth of the way across the square... and so on. For the eleventh set of lines, mark diagonal lines one-fifth of the way across. For the sixteenth set, mark diagonal lines which slope in the other direction.

Comments

We are sorry. New comments are not allowed after 1 days.