Barrel puzzle solution
-----------------------

First off, mentally number the six barrels like this, according to their
starting position:

1 4
2 5
3 6

Now, move the barrels in the following manner (the numbers refer to
the barrel numbers above. They do *not* stand for a specific number
of spaces):

6 up, 5 right, 5 down, 4 down, 6 right, 6 down, 6 left, 6 up, 6 right, 6 
down,
4 right, 4 down, 4 left, 4 up, 4 right, 4 down, 3 up, 2 right, 2 down, 2 
left,
1 down, 3 right, 3 down, 3 left, 5 left, 3 right, 3 down, 3 left