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Rules -- Blackbarrier Jam

Blackbarrier Jam was invented by the Japanese puzzle company Nikoli (under the name Kurodoko, FKA Where is Black Cells). It is one of several of their puzzles based on the unique rules regarding the placement of black cells in Japanese crosswords.


1. Determine whether each cell is white or black according to the following rules.
2. No numbered cell may be black.
3. A number indicates how many grid cells, including the cell itself, lie in an uninterrupted horizontal or vertical line from that cell, up to the perimeter of the puzzle, or a black cell (whichever is closer).
4. No two black cells may share an edge. All of the white cells must be connected to each other through their edges.

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