From WPC unofficial wiki


Divide the grid (except the shaded cells) into regions of given sizes, so that each region contains exactly one black circle and one white circle. No 2×2 square can be located completely within one region. The shaded cells are not part of any region.

(Rules and example from WPC 2019 IB)

History of the puzzle[edit]

Invented by Roland Voigt (Germany) in 2013. First appeared on Hausigel Contest Series.

Appearances in the past WPCs[edit]