Find and discuss an interesting example of recursion – thus, an example other than those presented in the readings.

Your discussion should: give citations, make it clear that this is either a head or tail recursion algorithm, and include both space and time big-O performance estimates of your example.

Propose a linear representation protocol of a binary tree data structure.

An example is RPN (reverse Polish notation) where a b + c * d e f + * / is a representation of the following tree:

(the tree is in the attachment).