NAME
Algorithm::Metric::Chessboard - Calculate distances on a square grid
with optional wormholes (the 'chessboard metric').
DESCRIPTION
Calculates minimum number of moves between two points in a game played
on a square grid, where one move is a jump from a point to a horizontal,
vertical or diagonal neighbour.
With no other features, the number of moves taken to go from the point
"(x1, y1)" to "(x2, y2)" *would* be quite simple:
d( (x1, y1), (x2, y2) ) = max( abs( x1 - x2 ), abs( y1 - y2) )
However within the space are "wormholes" which allow you to travel
between any two distant points in one move, so the actual number of
moves may be smaller than the above. Wormhole travel costs a fixed
number of moves.