决定学习怎么写翻转二叉树了.

[banxi1988]

https://twitter.com/mxcl/status/608682016205344768

from @mxcl
> Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.

[wdlth]

@lxrmido 不能使用CSS3，还得兼容各种浏览器，比如毒瘤IE6。