Want to save binary tree to disk for “20 questions” game

Question

In short, I\'d like to learn/develop an elegant method to save a binary tree to disk (a general tree, not necessarily a BST). Here is the description of my problem:

I\'

Answer 1

I would store the tree like this:

node data
[
  yes child]
[
  no child]

where the child nodes are just recursive instances of the above. The bits in [] are optional and the four identifiers are just constants/enum values.