CSCI 311 - Program 3

Graphs - Prim's Algorithm for finding a Minimal Spanning Tree

Dr. Melody Stapleton, Instructor

Shaun McCluskey  Teaching Assistant (TA)

Due Date:

• All Program Components: Friday, May 23- Last day of Final's Week - by MIDNIGHT!!!!

The TA will provide the final input file(s) to run your program against.

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Your assignment is to program the Prim's minimal spanning tree algorithm in a fashion similar to that shown on page 592 of Kruse's Chapter 12 on graphs (pages 23 and 24 in the Chapter 12 online notes) , but with some required modifications.  The code on page 592 (pages 23-24 of online notes) works with an adjacency table implementation of an undirected graph also know as just a graph or network.  You are to implement a graph using the "mixed" implementation scheme that is depicted on page 576 in Figure c).  You will then need to modify the code on page 592 (pages 23-24 of online notes) to work with the "mixed" implementation.  Use the ideas for implementation of a graph (aka network) that is not a digraph on P. 590 of Kruse.  In an undirected graph (graph or network) one must be sure that if there is an edge from x to y of weight w, there is also represented an edge from y to x of weight w.  I.e., the graph is symmetric.

You are to create a class "network" that will have a number of methods.  At the minimum it will have a constructor, destructor and a method to "read" in the relevant values to build the internal "mixed" representation of the graph.  Your input file format is specified below.  You will also need to build a method that "prints" the graph, and prints it in a way that looks like the picture on page 576, Figure c) (page 7 of the online notes, Figure c)).  I.e., you will print across a row, first the "from vertex" of an edge and then next to it print the list of "to" (or adjacent) vertices for that vertex.  Your first row will be for the "from" vertex 0, second row for the "from" vertex 1, etc.

Your "read' method for the graph class needs to process files in the following format:

*******************************************************************

8                  // number of vertices in the graph (values from 0 to 7)

0 1 5            // specifies there is an edge from 0 to 1 of weight 5 in the graph

1 2 10          //  specifies there is an edge from 1 to 2 of weight 10 in the graph

etc.

                    // blank line

3                  // source vertex

<end-of-file marker>

*******************************************************************

As soon as you have read in and processed all the edges of the graph, you need to then call your "print" method to print out the graph as described above.

Next, process the request to find the minimal spanning tree associated with the source vertex.  Once you have found the minimal spanning tree, which is constructed as a network, print out the minimum spanning tree with the same print routine you used to print out your original graph.

You will have at least 4 such weighted graph files to process with your program.