Rules (taken from Nikoli):
- Place light bulbs (circles) according to the following rules.
- Light bulbs may be placed in any of the white squares, the number in the square shows how many light bulbs are next to it, vertically and horizontally.
- Each light bulb illuminates from bulb to black square or outer frame in its row and column.
- Every white square must be illuminated and a light bulb can not illuminate another light bulb.