Author: Sven Reichard
Date: 14:53:27 09/09/02
Go up one level in this thread
Gerd,
I'm not exactly sure I understand the problem right. If I do, you have a
bitboard, and you want to walk a King from A to B stepping only on "on" squares
(we assume, A and B are on).
The (non-recursive) algorithm I can come up with is the following (excuse the
pseude-code:
procedure existsKingWalk(Square A, Square B, BitBoard allowed)
Bitboard reachable, oldReachable
clear(reachable)
set(reachable, A)
do
oldReachable = reachable
for all directions dir do
reachable |= (oldreachable shifted by dir)
od
reachable &= allowed
while reachable <> oldReachable and not reachable[B]
return reachable[B]
end
I haven't tested it, but it should be faster than checking each individual bit.
This can be modified to get the whole connectivity component (all squares the
king can reach).
Sven.
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