The easiest solution is as follows: Fill the 8 liter jug (then we have (4,8,0) in the 12 liter, 8 liter, and 5 liter, respectively.). Then fill the 5 liter with the 8 liter (4,3,5). Pour the five back into the 12 (9,3,0). Then transfer the 3 in the 8 liter jug into the 5 liter jug (9,0,3). Fill the 8 liter with the 12 liter (1,8,3). Then Finish filling the 5 liter with the 8 liter (1,6,5). Finally, pour the 5 liter back into the 12 liter bottle, for (6,6,0). Voila. Another solution is as follows: (12,0,0) -> (4,8,0) -> (0,8,4) -> (8,0,4) -> (8,4,0) -> (3,4,5) -> (3,8,1) -> (11,0,1) -> (11,1,0) -> (6,1,5) -> (6,6,0). Not too easy though.