※ 引述《saladim (殺拉頂)》之銘言：
: 看書又看到卡住 請大家幫忙解惑阿~~~~
: 所看的書是 Algorithms in C++ by Robert Sedgwick, 第18章的DFS小節(18.4)
: 裡面提到:
: We refer to a link from v to w in a DFS tree that represents a tree edge
: as :
: A tree link if w is unmarked
: A parent link if st[w] is v <