This is the testing strategy for assignment 4.
The input is in separate files for each case: testNN.in,
with corresponding expected output in testNN.out


1. empty tree
2. tree with one node (the root)
3. tree with two nodes (left branch)
4. tree with two nodes (right branch)
5. complete tree with three nodes
6. degenerate tree (left-branching)
7. degenerate tree (right-branching)
8. complete tree of 32 nodes
9. sample tree from assignment
10. big 'random' tree