Author: Alex Boby
Date: 10:39:12 05/08/01
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On May 08, 2001 at 11:50:40, Tony Werten wrote: >On May 08, 2001 at 01:58:00, Alex Boby wrote: > >> >>This has probably been asked a thousand times in the past so sorry for asking >>but I grep'd the archives and didn't find anything satisfying so here goes... >> >>How do most people deal with hash key collisions (2 positions, same key)? These >>cause problems for me currently because of illegal moves. I figure that there >>are 2 solutions... >> >>1) store the actual unique board position in the hash record for comparision. >>2) check the moves stored in the hash table to see if they are valid before >>using them. >> >>1 doesn't seem like a plausible solution (gigantic hash records) and 2 seems >>like it would be slow unless I could find a trick to do it easily. >> >>Is there a standard solution to this problem? > >Check the move. > >Normally move has a fromsquare, tosquare, frompiece and topiece. First check if >frompiece is on fromsquare and topiece is on toquare and if the color of topiece >is different from frompiece. > >Then I have an attacktable (works great in 0x88) where I can lookup if piece a >on square b can attack square c. > >When these conditions are met I accept the move. Not only because it's likeliy >the move is ok, but mainly because it won't make my engine crash anymore. ( I do >the left_my_own_king_in_check check when I make the move) > >Tony I don't store frompiece and topiece. I just look up what pieces are on fromsquare and tosquare.
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