The numeric keyboards of a telephone (left) and a pocket calculator (right) differ in the arrangement of the keys.

123   789
456   456
789   123
  0      0

What is the least number of moves necessary to transfer the keys of the first arrangement into the other arrangement?
One move consists of switching the position of two neighbouring keys (Horizontal, vertical or diagonal) of which the sum is 9, 10 or 11.
Example: In the starting position you can switch 6 and 3, 5 and 6, 4 and 5, 7 and 4, 0 and 9

29 switches (the best I got, to be beatten!!)

 

123..123..123..123..127..127..127..127..127..123..173..173

456..465..645..675..635..435..465..465..435..475..425..495

789..789..789..489..489..689..389..839..869..869..869..862

 

973..973..973..923..293..297..297..897..892..829..829..829

415..485..425..475..475..435..485..425..475..475..475..435

862..162..168..168..168..168..163..163..163..163..136..176

 

329..389..389..789...789...789

485..425..475..435...465...456

176..176..126..126...123...123<o:p></o:p>

Posted by pcbouhid on 2005-07-25 17:10:51