Shakashaka is a binary determination puzzle in which the cells in a grid are left unshaded or half-shaded into triangles.
The objective is to divide the grid into unshaded rectangles subject to the following rules:
- No two rectangles can share an edge.
- Cells can only be half-shaded into triangles, or left unshaded.
- Numbers in some cells denote the number of edges it shares with the shaded triangles.