CMPS 223 - Homework 7

Homework 7 - Weighted Directed Graphs

Extra Credit (no late assignments accepted)
Due: Monday, November 26, 2007 at 11:00am (before the final)

For this homework assignment, modify the directed graph code given in Figure 16.1 (Digraph.h) in the book. The modifications are as follows:

Add weights to the edges. Instead of list<int> adjacencyList, you will need a list of Edge classes. The edge class will contain an integer for the index of the endpoint and an integer for the weight of the edge. You will also need to modify any code that refers to the adjacency list so that it properly accesses the endpoint index.
Implement breadth-first search. The code has depth-first searching already. Add in the code for breath-first searching.
Modify shortest path. Modify the shortest path algorithm to use the edge weights according to Dijkstra's algorithm.
Change read() to read from a comma-seperated file. Currently the read function reads from a file like NetworkFile shown in Figure 16.2. Modify it to read from a file that has the following format:
```
node value, endpoint1 weight1, endpoint2 weight2, ... , endpointN weightN
```
For example:
```
Los Angeles, 3 7, 4 12
San Francisco, 3 10, 1 2, 4 7
Denver, 1 8, 2 7
Chicago, 2 9, 3 2, 1 10
```
Update for Helios compiler. The book code was written for an old compiler. You may need to add typename as described in Lab 6 in order to compile it on Helios.

Menu Program

Write the following menu program to test your directed graph code.

     Welcome to the Directed Graph menu
----------------------------------------------
1. Read in a directed graph from a file
2. Do a depth-first search 
3. Do a breadth-first search
4. Compute the shortest path between two nodes
5. Print the directed graph

0. Exit
----------------------------------------------

For option 1, prompt the user for a filename, open the file and then call the read function on that file.

For options 2 and 3, prompt the user for the index of the starting node and then perform the search from that starting node. If the whole graph cannot be searched from that node, select an unprocessed node at random and repeat the search until all the nodes have been processed.

For option 4, prompt the user for the index of the starting node and the index of the destination node. Call the shortest path function with these two nodes. Print out the shortest path if the destination can be reached or "destination not reachable" if it cannot.

For option 5, call the display function.