Painting a Cube
Source: Tournament of Towns Spring 2016 Junior A-Level
February 23, 2017
combinatoricsgeometry3D geometry
Problem Statement
A designer took a wooden cube , divided each face into unit squares and painted each square black, white or red so that any two squares with a common side have different colours. What is the least possible number of black squares? (Squares with a common side may belong to the same face of the cube or to two different faces.)
(8 points)Mikhail Evdokimov