Kuromasu is a binary determination puzzle in which the cells in a grid are split into either shaded or unshaded.
The objective is to divide the grid into shaded and unshaded cells, subject to the following rules:
- No numbered cell can be shaded.
- Numbers represent the number of unshaded cells that can be seen from that cell, including itself. A cell can be seen from another cell if they are in the same row or column, and there are no shaded cells between them in that row or column.
- Shaded cells must never touch horizontally or vertically.
- Unshaded cells must form one, connected area.
A standard 10x10 kuromasu and its solution.