1. Write a C++ class derived from Graphic Interface, as given in Listing 20-1. Use an adjacency matrix to represent the graph.
2. Repeat the previous programming problem, but represent the graph using an adjacency list instead of an adjacency matrix.
3. Repeat Programming problems 1 and 2, but allow the graph to be either weighted or unweighted and either directed or undirected.
4. Extend Programming Problem 3 by adding ADT operations such as is Connected and has Cycle. Also, include operations that perform a topological sort for a directed graph without cycles, find the Depth First Search and Breadth First Search spanning trees for a connected graph, and find a minimum spanning tree for a connected undirected graph.