The objective is to shade some cells, subject to the following rules:
- Numbers indicate how many shaded cells are in a room.
- Shaded cells must never touch horizontally or vertically.
- Unshaded cells must form one, connected area.
- A straight line of unshaded cells can only cross over one border at the most, even if it would re-enter a room.
- No two numbers with the same value can appear unshaded in the same row or column.
A standard 10x10 heyawake hitori puzzle and its solution.