Copyright © University of Cambridge. All rights reserved.
Lachlan was playing with his bear counters.
He had four blue, then four red followed by four yellow and finally four green bears.
"What are you doing now?" Jenni asked.
"I want to arrange them so that no two bears of the same colour are next to each other", he said.
"That's easy!" cried Jenni.
"Ah, but you have to do it in the least number of moves possible", replied Lachlan.
What's the least number of moves you can take to rearrange the bears?