dfs序

两篇入门博客:

http://blog.csdn.net/viphong/article/details/50561976

https://www.cnblogs.com/zhouzhendong/p/7264132.html

性质:

1,每个节点的子树范围为in[x]~out[x]

2,每个节点的序号本身为in[x]

题目:

1, HDOJ5692 题解:   http://www.cnblogs.com/zhouzhendong/p/7263838.html