You have a 4×5 chess board as follows:

You can move the four bishops in any order (not necessarily alternating black and white), provided that no move puts a piece in danger of being captured by a bishop of the opposite color.

What is the fewest number of moves needed for the black and white bishops to exchange places?

(In reply to re: A switch solution - maybe not the optimal one... by Federico Kereki)

The reason for the mix up: I used the chess board to find the solution to the problem. And on a chess board, the first field (the one in the lower left corner) is a1, and on the picture above, that field is a4. :) But what about the number of moves? Can there be less than 19 (legal) moves?

Posted by slsl on 2004-03-02 10:05:48