Heyawake (from Japanese, “divided rooms”) is played on a rectangular grid. The grid is divided into rectangular “rooms”. Some rooms may contain a single number. These rooms must have the designated number of cells painted black. Other rooms may have zero or more cells painted black.
• Black cells must not be orthogonally connected.
• All white cells must be interconnected.
• A line of connected white cells must not connect more than two rooms together.