Description of the problem

In computer science, an in-tree or parent pointer tree is an N-ary tree data structure in which each node has a pointer to its parent node, but no pointers to child nodes.

Example of the problem

https://opendsa-server.cs.vt.edu/ODSA/Books/Everything/html/UnionFind.html

References/Other comments

https://en.wikipedia.org/wiki/Parent_pointer_tree