Assignment #11.

A. Implement the void Cutset() as a public member function in you class DiGraph. Cutset() determines a small
set of nodes that, if removed, would break all cycles in the graph.

B. Download the file digraphData.zip. This file contains several random digraphs for testing you digraph class.
There are 6 files named grN_s.txt, where N is the number of
nodes and s is the sparsity factor,  defined as the number of edges divided by N^2. Each file begins with the number of nodes
and number of edges, followed by a node pair for each edge. Nodes are numbered 0, 1,... N-1. You can use these graphs
to test your digraph class. I would suggest drawing a couple of the smaller ones so you can verify that your dfs is
working. It will be pretty hard for you (or me!) to verify dfs for the larger graphs, as dfs orderings are not unique.

I also include the program I used to generate the graphs. You are welcome to experiment with it. Frankly, I'm not terribly
happy with the graphs it generates. They are proper graphs, and the are random, but in a curious way.

Test the functionality of your class DiGraph using the small graphs gr5_9 gr10_5. Your output should do the displays in the following order, with appropriate headings:

1. Dispalay the graph with the print() function.
2. Display the depth first ordering
3. Display the cut set.

C. Do timing tests for finding cut sets for the larger graphs gr20_3.  gr100_1, gr500_07, and gr100_05. Obviously, you
should not display these larger graphs. Instead, your output should display the following  in the given order,
with appropriate headings:

1. Display the cut set.
2. Display the time it took to do the cut set.