You have three large and two small coins, placed in a row as OxOxO (O large, x small).

logic/five.coins New

New entry, edited from material collected for the archive and not yet in a released version.

Problem

You have three large and two small coins, placed in a row as OxOxO
(O large, x small).  A move consists of moving two neighbouring coins
together, without switching their order, and putting them against
coins already present.  In how few moves can you end up with OOOxx?

-- Erik Hoogers <eh@e_nx_eh.nl.stratus.com>

[ Editor: problem statement condensed from the posting:

  You only have three large and two small coins.
  Position them as follows :                   OxOxO
  Now, by moving two neighbouring coins at a time,
  not switching position,
  putting them against already present coins.
  In how many (little) moves can you end up in OOOxx ? ]

Show solution

I did it in three moves.  (I hope I understood the rules.)

-- Jeannie Biesiada <biesiada2@llnl.gov>

[ Editor: her solution was snipped in the reply that quoted it and is
not in the collected material. ]

How about this: following the original rules for moving the coins, can
you end up with all the big coins together on the left and the little
ones on the right in only *two* moves?

-- Admiral Jota <jota@laraby.tiac.net>

Sure.

Start with                                    OxOxO

Move the 3rd and 4th to the end to give       OxOOx
Move 3rd and 4th to the front, giving         OOOxx

Two moves.

-- David Howse <David.Howse@anu.edu.au> (July 1996)