http://www.doc88.com/p-35322059878.html
《算法导论》习题解答 Chapter 22.1-3(转置图)
http://blog.youkuaiyun.com/hcbbt/article/details/9337887
算法导论-22.4-5-用队列实现拓扑排序
http://blog.youkuaiyun.com/mishifangxiangdefeng/article/details/7840091
求有向图的强连通分量(scc):Tarjan算法
http://kmplayer.iteye.com/blog/604532