Overview
Junior
Construction and proof problems where cells of a grid, faces, vertices, or edges of a solid must be coloured subject to local adjacency or count constraints.
Practice
4×4 Board: Each Cell Borders Exactly One Opposite
4×4 Board: Six Black Cells with Even Row and Column Counts
6×6 Board: Three Colours in Every Three-Cell Strip
8×8 Good Colouring: Find 16 Black Cells
4×4 Board: Each Cell Borders Exactly Two Opposite
4×4 Board: Four Colours in Every Rectangle and Square
Cube Vertices: Two Opposite-Colour Neighbours Each
Cube Faces: Two Opposite-Colour Neighbours Each
4×4 Board: Each White Borders One Black, Each Black Borders Three White
8×8 Good Colouring: At Most 16 Black Cells
More practice problems →