- ➊ Draw a single closed loop which does not cross or touch
- ➋ The sections of the loop run horizontally or vertically
between the center points of
orthogonally adjacent cells.
- ➌ The loop must visit all cells with a white or a black
circle but not necessarily all other cells.
- ➍ In a cell with a black circle the loop must turn by 90° and
must travel straight through the previous and next cell.
- ➎ In a cell with a white circle the loop must travel straight
through and must turn by 90° on the previous or the next cell.