- ➊ Draw a single closed loop along the grid lines of the
diagram which does not visit a grid dot twice.
- ➋ All numbered cells must be inside of the loop.
- ➌ A number in a cell indicates how many cells inside of the
loop are seen from this cell looking to the north, south, east and west. The
cell with the number is counted exactly once.
- ➍ Other numbers do not block the visibility of cells behind
it, but cells outside of the loop do so (you cannot look through an outside
cell to another inside cell).