Nondango

Nondango (dango is a Japanese dish, small balls made from rice flour and skewered on bamboo sticks) is a logic puzzle published by Nikoli. A rectangular or square grid is divided into regions. Each region contains circles in some cells. The aim is to blacken some circles according to the following rules:

• Each region contains one black circle.
• Three consecutive circles of the same color never appear in any row, column or diagonal. There must be a circle of other color or an empty cell between them.

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