Akari

Example puzzle on the left, solution on the right

Akari is a puzzle made by nikoli.

1. Put a “lightbulb” in some cells of the grid so the whole grid is illuminated by lightbulbs.
2. A square can only be occupied by one lightbulb.
3. A lightbulb illuminates all cells in the same row and column, but is obstructed by “walls” (black cells).
4. A number on a wall determines the number of lightbulbs orthogonally adjacent to the wall.
5. Lightbulbs may not illuminate other lightbulbs.