http://www.cnblogs.com/xiaowuyi/archive/2012/03/17/2404015.html
http://my.oschina.net/lenglingx/blog/204086
http://blog.csdn.net/goof/article/details/7921851
http://www.jb51.net/article/49219.htm
http://www.cnblogs.com/lonelycatcher/archive/2012/02/09/2343480.html
http://blog.chinaunix.net/uid-26000296-id-4356230.html
http://jingyan.baidu.com/article/b24f6c822784b886bfe5dabe.html
http://wenku.baidu.com/view/5536db7ae87101f69e3195f4.html
http://wenku.baidu.com/view/42b953f8c8d376eeaeaa3194.html
http://www.cnblogs.com/lonelycatcher/archive/2012/02/09/2343463.html
http://www.jb51.net/article/49216.htm
http://www.iteye.com/problems/50919