A星寻路＋堆排序
http://www.vckbase.com/document/viewdoc/?id=1422
http://www.cppblog.com/christanxw/archive/2006/04/07/5126.html
http://www.gamedev.net/page/resources/_/technical/artificial-intelligence/a-pathfinding-for-beginners-r2003
http://v.youku.com/v_show/id_XMjQzMTYzNjg4.html
堆排序
http://zh.wikipedia.org/wiki/%E5%A0%86%E6%8E%92%E5%BA%8F#cite_note-1
