Exchange the black knights with the white knights
as shown in Figure 1 in the minimum possible number of moves. One move
is a normal knight's move on any vacant cell of the board.
Figure 2 shows some moves of the chess knight which may be done as
A - one cell in one direction (horizontal or vertical), and then two
cells in other direction (vertical or horizontal) - one such a move is
shown in Figure 2,a;
B - two cells in one direction (horizontal or vertical), and then one
cell in other direction (vertical or horizontal) - Figure 2,b shows
one of such moves.
You may want to use our printable 3x3 board to solve the puzzle. Just
print it out form the
Print 'n' Play PDF Version, take two pairs of
chess knights or simple coins, and place them on the start cells. Now
you're ready to solve the puzzle.