The origin of this puzzle is not known.
Puzzle and Goal
An unsolved puzzle consists of a rectangular grid divided into irregular regions. Some of the regions contain number clues.
The goal is to blacken some of the cells based on the clues.
The solved grid must satisfy the following conditions:
Each region contains a single orthogonally adjacent cluster of black cells.
If a region contains a number, that represents the size of the cluster in that region.
Two orthogonally neighboring regions cannot contain clusters of the same size.
Two clusters cannot be orthogonal neighbors; that is, wherever two cells are separated by a region wall, at least one must be white.
There are no restrictions on white cells.