searching a list of lists as a two-dimensional array?

[Paul Rubin]

"agent-s" <shanekwon at gmail.com> writes:
> Basically I'm programming a board game and I have to use a list of
> lists to represent the board (a list of 8 lists with 8 elements each).
> I have to search the adjacent cells for existing pieces and I was
> wondering how I would go about doing this efficiently. Thanks

You're getting a bunch of Pythonic suggestions which are easy to
understand though not so efficient.  If you're after efficiency you
might look at a book like Welsh and Baczynskyj "Computer Chess II" for
some techniques (warning, this is a rather old book though) and
program in a closer-to-the-metal language.  One common approach these
days is "bit boards".  Basically you represent the board state as a
bunch of 64-bit words, one bit per square.  So for checking occupancy,
you'd have a word having the bits set for occupied squares.  If you
only want to check adjacent squares (king moves), you could have a
bunch of bit masks (one for each square) with bits set only for the
adjacent squares (similarly for bishop moves, rook moves, etc.)  Then
to check adjacency you'd mask off the appropriate bits for that
square, then AND it against the occupancy word.  Normally you'd have
separate occupancy words for your own pieces and your opponent's.