Project 2
Deadline: March 24 @ 4 PM

Output: Edges & Cost
- Each edge with its cost
  * Ascending order of cost
- Total tree cost

Abstract data type often (always?) come with invariants 
- Particularly when it is directly associated with an algorithm.

e.g. two ADTs can (but aren't required) to be implemented with a binary tree
1. Binary Search Tree (BST)
  * Invariant - All elements in left subtree are smaller, all in right subtree are larger

2. Priority Queue
  * Invariant - the elements in a node's children are:
    - Greater if it is a min-queue
    - Less if it is a max queue

An invariant is something that is always true when an ADT's implementation is not being operated on



Traversals