There is just one way to go from XXXXOOOO to XOXOXOXO in five moves if *three* adjacent coins are moved at each turn. How?

Based on the assumption (since this problem went through the queue before it was answered) that on each turn we are moving a group of three adjacent coins as a single unit, this is what I found:

XXXXOOOO
XXXOXOOO
XOXOXXOO
XOXXOXOO
XOXXOOXO
XOXOXOXO

(The group moved in each step in in bold; the position it was moved to is underlined)

Posted by DJ on 2004-10-26 19:34:06