Dosun-Fuwari

Dosun-Fuwari is a logic puzzle published by Nikoli. The task consists of a grid divided into regions. The grid may contain black cells; black cells do not belong to any region. The aim is to place one black circle and one white circle in each region according to the following rules:

Dosun-Fuwari

Cross+A can solve puzzles from 3 x 3 to 30 x 30.