Question

A 1×6 square unit rectangular grid has to be covered with six 1×1 square unit tiles. Three of the tiles are yellow, two are white, and one is blue. In how many ways can this task be done if

b: no two neighboring tiles are the same color
(btw if there are no restriction the answer would be 60)

Answer 1

BW... does not work, since that would force BWYWYY

So BYWYWY is one arrangement

Now start with W or Y and see what is available