Logic Masters Deutschland e.V.

Place mirrors into the grid to direct a ray of light from the entering cell to the exit cell, both marked with arrows. The ray has to pass every cell containing a number at least once and may cross itself. It enters and exits the diagram in the directions specified by the arrows. Light that enters the entering or exit cells perpendicular to the arrow passes these cells unaffectedly. Mirrors are placed diagonally into empty cells, there may as well be mirrors in the entering or exit cell. Both sides of a mirror reflect light in a right angle. No unused mirrors are placed. Cells containing mirrors do not touch, not even diagonally. Numbers indicate the lengths of each part of the ray (restricted by mirrors or the start/exit of the ray) which passes through their cell. The length of such a part equals the number of lines of the grid it crosses.

Example