Add Linck cut tree

[EzElephant]

Outline

LCT實作

• splay_tree須知
• access
• make_root
• link
• cut

LCT用途

• LCT可以用來解哪些問題
• 時間複雜度分析

例題

• 模板題(Dynamic_Tree_Connectivity)
• DYNALCA - Dynamic LCA
• QTREE6 - Query on a tree VI
• Train Tracks
  除了模板題以外的三題會選兩題做講解

Reference

https://oi-wiki.org/ds/lct/
http://sunmoon-template.blogspot.com/2015/11/link-cut-tree.html
https://codeforces.com/blog/entry/80383
https://github.com/enkerewpo/OI-Public-Library/blob/master/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%20DATA%20STRUCTURE/Link%20Cut%20Trees.pdf