Author: Anurag Sahay
Draw a single continuous loop in the grid using horizontal and vertical line segments. It should not cross or overlap itself. Numbers in the grid show how many of eight neighboring cells are visited by the loop. The loop can't go through a cell with digits.
Grid control: To draw a line press the mouse button at a start cell and move mouse to another cell holding the button. You can also put auxiliary marks by clicking at cells. More details about grid control are at the help page.