Gamer say:

Spiral the words Gamer says around in a 3 by 3 board like this:

G A M
Y   E
A S R

On each turn, you may slide one letter horizontally or vertically into the blank space (the square it moved from becomes the new empty square).

You want to rearrange the letters so that the same word is spelled out around the edge, but beginning from one of the edges instead of the corner.

In other words, the board should look like one of these configurations:

Y G A  S A Y  E R S  A M E
A   M  R   G  M   A  G   R
S R E  E M A  A G Y  Y A S

What is the fewest number of turns it takes to do this?

If we call the first A a, then

aGYa produces

YGM
a E
ASR

then aASa produces

YGM
A E
SaR

then AYGA produces

GAM
Y E
SaR

then aREa produces

GAM
Y a
SRE

then aMAa produces

GaA
Y M
SRE

and aGYa produces

YGA
a M
SRE

That's 6 x 4 = 24 moves.

But there were two places where a was moved twice in a row.

So once those two pairs are shortcutted, this is a 20-move solution.

Posted by Charlie on 2004-03-18 16:09:49