Describe, in detail, how the createWeightedGraph( ) method works.

import java.util.*; iimport java.text.*;

class WeightedGraph extends Graph { protected double[][] weights; //weight matrix protected double[] smallestWeight; //smallest weight from //source to vertices

//default constructor public WeightedGraph() { super(); weights = new double[maxSize][maxSize]; smallestWeight = new double[maxSize]; } //constructor with a parameter public WeightedGraph(int size) { super(size);

weights = new double[maxSize][maxSize]; smallestWeight = new double[maxSize]; } public void createWeightedGraph() throws IOException, FileNotFoundException { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); String fileName; StringTokenizer tokenizer; int index; int vertex; int adjacentVertex; if(gSize != 0) //if the graph is not empty, make it empty clearGraph(); System.out.print("Enter input file name: "); fileName = keyboard.readLine(); System.out.println(); BufferedReader infile = new BufferedReader(new FileReader(fileName));

gSize = Integer.parseInt(infile.readLine()); //get the number //of vertice

for(index = 0; index < gSize; index++) { tokenizer = new StringTokenizer(infile.readLine()); vertex = Integer.parseInt(tokenizer.nextToken()); adjacentVertex = Integer.parseInt(tokenizer.nextToken()); while(adjacentVertex != -999) { graph[vertex].insertLast(new IntElement(adjacentVertex)); adjacentVertex = Integer.parseInt(tokenizer.nextToken()); } //end while } // end for

for(int i = 0; i < gSize; i++) for(int j = 0; j < gSize; j++) weights[i][j] = infinity;

double weight; String inputLine;

inputLine = infile.readLine(); while(inputLine != null) { tokenizer = new StringTokenizer(inputLine); vertex = Integer.parseInt(tokenizer.nextToken()); adjacentVertex = Integer.parseInt(tokenizer.nextToken());

while(adjacentVertex != -999) { weight = Integer.parseInt(tokenizer.nextToken()); weights[vertex][adjacentVertex] = weight; adjacentVertex = Integer.parseInt(tokenizer.nextToken()); }

inputLine = infile.readLine(); } } //createWeightedGraph

//The function to determine the smallest weight from, //vertex, that is, the source to every other vertex //in the graph. public void shortestPath(int vertex) { int i,j; int v = 0; double minWeight;

for(j = 0; j < gSize; j++) smallestWeight[j] = weights[vertex][j];

boolean[] weightFound = new boolean[maxSize];

for(j = 0; j < gSize; j++) weightFound[j] = false;

weightFound[vertex] = true; smallestWeight[vertex] = 0;

for(i = 0; i < gSize - 1; i++) { minWeight = infinity;

for(j = 0; j < gSize; j++) if(!weightFound[j]) if(smallestWeight[j] < minWeight) { v = j; minWeight = smallestWeight[v]; }

weightFound[v] = true;

for(j = 0; j < gSize; j++) if(!weightFound[j]) if(minWeight + weights[v][j] < smallestWeight[j]) smallestWeight[j] = minWeight + weights[v][j]; } //end for } //end shortestPath

//Method to print the shortest weight from the //source to the other vertices in the graph. public void printShortestDistance(int vertex) { DecimalFormat twoDigits = new DecimalFormat("0.00");

System.out.println("Source Vertex: " + vertex); System.out.println("Shortest Distance from Source " + "to each Vertex"); System.out.println("Vertex Shortest_Distance");

for(int j = 0; j < gSize; j++) System.out.println(" " + j + " \t\t" + twoDigits.format(smallestWeight[j])); System.out.println(); } }