Question 73
A $3 \times 3$ grid is given. You shall color each square with one of the given colors. However, you may not color two squares sharing an edge with the same color. How many such colorings are there if you can use
(1) three colors (say red, blue and green)?
(2) four colors (say red, blue, green and yellow)?
It is not necessary to use all the colors. We consider two colorings different even if they correspond by rotation and/or reversal.
(1) three colors (say red, blue and green)?
(2) four colors (say red, blue, green and yellow)?
It is not necessary to use all the colors. We consider two colorings different even if they correspond by rotation and/or reversal.