what? It’s time again for another Bikwil mind bender. Though no
cinch, this one ought to be simpler than our notorious “Twelve Billiard
Balls Puzzle” (Issue 4, November 1997).
“Five Coin Puzzle” concerns coins lying in a straight row,
all touching — three 20-cent coins and two 10-cent coins.
you start, they are positioned so that the coin types alternate, with a
20-cent coin on the left. Your goal is, in as few moves as possible, to
arrange them (again in a straight line), so that the 20-cent coins end
up together on the left, then the 10-cent coins, all touching.
starting with this:
20 10 20
have to get to this:
20 10 10.
are the rules for moving the coins:
must be slid, not picked up;
adjacent coins (always of different types) must be moved
least one of the pair moved must touch a third coin after
coins moved must not change their left-to-right
orientation (in other
words, 20 10 must not be twisted to 10