Light Up Solver
Solve a Light Up (Akari) puzzle by placing the bulbs.
Light Up, also called Akari, asks you to place bulbs on a grid so that every white cell is lit. A bulb lights its own cell and shines along its row and column until a wall stops it, no two bulbs may shine on each other, and a numbered wall must touch exactly that many bulbs. Click a cell to cycle it through white, a plain wall, and walls numbered 0 to 4, then solve.
Click a cell to cycle white, wall, then walls numbered 0 to 4.
How it works
Each row and column of white cells between walls is a segment that can hold at most one bulb, and a cell is lit when its row segment or its column segment has a bulb. The solver decides each white cell bulb or empty, keeps every numbered wall on track for its exact count, and never leaves a cell that can no longer be lit.
A proper Light Up puzzle has a single arrangement of bulbs; the solver reports when more than one works.