Programmer Puzzle: Encoding a chess board state throughout a game

Question

Not strictly a question, more of a puzzle...

Over the years, I\'ve been involved in a few technical interviews of new employees. Other than asking the standard \"do you

Answer 1

As several others have mentioned you could for each of the 32 pieces you could store which square they're on and if they're on the board or not, this gives 32 * (log2(64) + 1) = 224 bits.

However the bishops can only occupy either the black or white squares so for these you only need log2(32) bits for the position, which give 28 * 7 + 4 * 6 = 220 bits.

And since the pawns don't start at the back and can only move forward, they can only be on 56, it should be possible to use this limitation to reduce the number of bits needed for the pawns.