A Six-Color Square
Color each square of a 6x6 grid of squares with one of six colors
(say A, B, C, D, E and F)
such that:
- Each row contains each of the six colors.
- Each column contains each of the six colors.
- Each main diagonal contains each of the six colors.
- The squares along each main diagonal cannot touch squares of the same
color, even at corners.
(Same-color corner-touching is allowed off of the main diagonals.)
Source: A reader's physics teacher.
(If anyone has a better source, let me know.)
Solution
Mail to Ken