import java.util.scanner; import java.io.*;

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Garey Gregory
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1 // Driver.java /** * Programmer: Kenneth Eaton * Course: COSC 439 * Professor: Dr. Tehranipour * Date: 12/11/2007 * Project: Project 3, Routing Table with Dijkstra's Algorithm * * Purpose: This program uses a text file containing a * weighted, undirected graph as input. It interprets * the text file to determine which Nodes of the * graph are adjacent and the weight of each path * between adjacent nodes. The program then runs * Dijkstra's Algorithm on each node of the matrix * to determine the shortest path between each of the * nodes. Afterward it prints the routing table to * the screen and a text output file. import java.util.scanner; import java.io.*; public class ke_driver { private static PrintWriter out; private static String[] order; private static ke_matrixhandler matrix = new ke_matrixhandler(); private static ke_pqueue settled = new ke_pqueue(), unsettled = new ke_pqueue(); private static final int INFINITY = , NIL = -1; private static int M_DIMENS; // Get the info from text file, and enter it into the matrix private static void initialize_matrix(string[] args) throws IOException { out = matrix.creatematrix(args); M_DIMENS = matrix.size; /* This method saves the order in which the nodes are * settled so the rows and columns of the matrix will * match up when printed in the table. private static void createtemporderarray() { order = new String[M_DIMENS];

2 for(int i=0; i < M_DIMENS; i++) { order[i] = unsettled.getel(i).getname(); /* * The following method enters each vertex into * the unsettled priority queue and initializes * the label to "infinity" and previous vertex to * "NIL"for each vertice entered into the queue private static void initializeq() { // Enter 'a' into the queue with 0 for // it's label and "NIL" for it's previous unsettled.enqueue(new ke_node(0, 0, NIL, matrix.names[0])); for (int i = 1; i < M_DIMENS; i++) { // Each vertex after 'a' entered into unsettled queue unsettled.enqueue(new ke_node(i, INFINITY, NIL, matrix.names[i])); for (int j = 0; j < M_DIMENS; j++) { // Initialize which vertices are adjacent to each other if (matrix.adjacencies[i][j] < INFINITY) { unsettled.lastel().setadjacencies(j); /* This method uses initializeq() after rearranging * the adjacency matrix to allow the program to run * Dijkstra's Algorithm on the different nodes of * the matrix. private static void initializeq(int iter) { matrix.reinitializematrix(); initializeq(); private static int relax_neighbors(ke_node u) { int lowest_weight = INFINITY, lowest_weight_index = -1; //Renew each label in unsettled queue //if the new label is less then the old label for (int i = 0; i < M_DIMENS-(settled.QSize()); i++) { if (u.getlabel() + matrix.adjacencies [u.getindex()][unsettled.getel(i).getindex()] < unsettled.getel(i).getlabel()) {

3 queue unsettled.getel(i).setlabel(u.getlabel() + matrix.adjacencies [u.getindex()][unsettled.getel(i).getindex()]); //Set the previous vertex unsettled.getel(i).setprevious(u.getindex()); //Return the index of the next smallest label in the unsettled for (int i = 0; i < M_DIMENS-(settled.QSize()); i++) if (unsettled.getel(i).getlabel() < lowest_weight ) { lowest_weight = unsettled.getel(i).getlabel(); lowest_weight_index = i; return lowest_weight_index; /* This method prints out the header and first row are * of the routing table to the screen and the output file. private static void printresults() { System.out.print("\t" + order[i]); out.print("\t" + order[i]); System.out.print("\n\n" + settled.getel(0).getname() + "\t"); out.print("\n\n" + settled.getel(0).getname() + "\t"); for (int j=0; j < M_DIMENS; j++) if (order[i].equals( settled.getel(j).getname()) ) { if (settled.getel(j).getlabel() == 0) { System.out.print("--\t"); out.print("--\t"); System.out.print(settled.getEl(j).getLabel() + "\t"); out.print(settled.getel(j).getlabel() + "\t"); /* This method prints out the rest of the routing table * after the header and first row are printed.

4 private static void printresults(string[] order) { System.out.print("\n" + settled.getel(0).getname() + "\t"); out.print("\n" + settled.getel(0).getname() + "\t"); for (int j=0; j < M_DIMENS; j++) if (order[i].equals( settled.getel(j).getname()) ) if (settled.getel(j).getlabel() == 0) { System.out.print("--\t"); out.print("--\t"); System.out.print(settled.getEl(j).getLabel() + "\t"); out.print(settled.getel(j).getlabel() + "\t"); public static void main(string[] args) throws IOException { boolean firstrowfinished = false, done = false; int nextindex, iterations = 0; initialize_matrix(args); initializeq(); createtemporderarray(); for (iterations = 0; iterations < M_DIMENS; iterations++) { if (!(iterations == 0) ) initializeq(1); //Dequeue the first element settled.enqueue(unsettled.dequeue()); //For each vertex in unsettled... while (!unsettled.isempty()) { //Find the next smallest label in unsettled nextindex = relax_neighbors(settled.lastel()); //Enqueue the smallest label from unsettled settled.enqueue(unsettled.dequeue(nextindex)); //Print the header and first row of the matrix if (!firstrowfinished) { printresults(); firstrowfinished = true; // Print the rest of the matrix

5 printresults(order); System.out.println(); out.println(); // Renew the settled Queue settled = new ke_pqueue(); out.close(); matrix.killout(); /***** Dijkstra's Algorithm Psuedocode ***** 1 function Dijkstra(G, w, s) 2 for each vertex v in V[G] // Initializations 3 d[v] := infinity // Unknown distance function from s to v 4 previous[v] := undefined 5 d[s] := 0 // Distance from s to s 6 S := empty set // Set of all visited vertices 7 Q := V[G] // Set of all unvisited vertices 8 while Q is not an empty set // The algorithm itself 9 u := Extract_Min(Q) // Remove best vertex from priority queue 10 S := S union {u // Mark it 'visited' 11 for each edge (u,v) outgoing from u 12 if d[u] + w(u,v) < d[v] // Relax (u,v) 13 d[v] := d[u] + w(u,v) 14 previous[v] := u *******************************************

Routing Protocols and the IP Layer

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