Hints for first Puzzle Baron's Logic Puzzles Book (2010)

[Disoriented]

2. Barber Shop (127)

Change Clue 1 to the following: The five customers are the one who was served first, the one who got the flattop, Matthew, the customer who requested a crew cut (who wasn't served fourth), and the one who has prematurely gray hair (who isn't Alan and who wasn't served third).

Change Clue 3 to the following: Trevor got his haircut before Matthew. Neither Trevor nor Matthew has brown hair.

That’s not quite right? I think you mean to say we should assume that Alan wasn’t served third. We already know the gray-haired man wasn’t served third from combination of clues 1 and 4.

It has to be this way, as the solution does not appear to be unique otherwise.