i found lvl 10 easy :S, and my solution were pretty better than walkthrought.. still i thought lvl 11 nuch harder ^^..
its a pity i havnt print screend my lvl 10 solution QQ
i personally found lvl 11 hardest.... but it took me not much time to figure that out
heres my solution
http://img31.imageshack.us/img31/5960/ownh.jpg
not the best but it does the job....
pls post ur solutions as well ^^