Code:
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.PriorityQueue;
import java.util.Scanner;
public class BestFirstSearch
{
private PriorityQueue
private int heuristicvalues[];
private int numberOfNodes;
public static final int MAX_VALUE = 999;
public BestFirstSearch(int numberOfNodes)
{
this.numberOfNodes = numberOfNodes;
this.priorityQueue = new PriorityQueue
new Vertex());
}
public void bestFirstSearch(int adjacencyMatrix[][], int[] heuristicvalues,int source)
{
int evaluationNode;
int destinationNode;
int visited[] = new int [numberOfNodes + 1];
this.heuristicvalues = heuristicvalues;
priorityQueue.add(new Vertex(source, this.heuristicvalues[source]));
visited[source] = 1;
while (!priorityQueue.isEmpty())
{
evaluationNode = getNodeWithMinimumHeuristicValue();
destinationNode = 1;
System.out.print(evaluationNode + "\t");
while (destinationNode <= numberOfNodes)
{
Vertex vertex = new Vertex(destinationNode,this.heuristicvalues[destinationNode]);
if ((adjacencyMatrix[evaluationNode][destinationNode] != MAX_VALUE
&& evaluationNode != destinationNode)&& visited[destinationNode] == 0)
{
priorityQueue.add(vertex);
visited[destinationNode] = 1;
}
destinationNode++;
}
}
}
private int getNodeWithMinimumHeuristicValue()
{
Vertex vertex = priorityQueue.remove();
return vertex.node;
}
public static void main(String... arg)
{
int adjacency_matrix[][];
int number_of_vertices;
int source = 0;
int heuristicvalues[];
Scanner scan = new Scanner(System.in);
try
{
System.out.println("Enter the number of vertices");
number_of_vertices = scan.nextInt();
adjacency_matrix = new int[number_of_vertices + 1][number_of_vertices + 1];
heuristicvalues = new int[number_of_vertices + 1];
System.out.println("Enter the Weighted Matrix for the graph");
for (int i = 1; i <= number_of_vertices; i++)
{
for (int j = 1; j <= number_of_vertices; j++)
{
adjacency_matrix[i][j] = scan.nextInt();
if (i == j)
{
adjacency_matrix[i][j] = 0;
continue;
}
if (adjacency_matrix[i][j] == 0)
{
adjacency_matrix[i][j] = MAX_VALUE;
}
}
}
for (int i = 1; i <= number_of_vertices; i++)
{
for (int j = 1; j <= number_of_vertices; j++)
{
if (adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
{
adjacency_matrix[j][i] = 1;
}
}
}
System.out.println("Enter the heuristic values of the nodes");
for (int vertex = 1; vertex <= number_of_vertices; vertex++)
{
System.out.print(vertex + ".");
heuristicvalues[vertex] = scan.nextInt();
System.out.println();
}
System.out.println("Enter the source ");
source = scan.nextInt();
System.out.println("The graph is explored as follows");
BestFirstSearch bestFirstSearch = new BestFirstSearch(number_of_vertices);
bestFirstSearch.bestFirstSearch(adjacency_matrix, heuristicvalues,source);
} catch (InputMismatchException inputMismatch)
{
System.out.println("Wrong Input Format");
}
scan.close();
}
}
class Vertex implements Comparator
{
public int heuristicvalue;
public int node;
public Vertex(int node, int heuristicvalue)
{
this.heuristicvalue = heuristicvalue;
this.node = node;
}
public Vertex()
{
}
@Override
public int compare(Vertex vertex1, Vertex vertex2)
{
if (vertex1.heuristicvalue < vertex2.heuristicvalue)
return -1;
if (vertex1.heuristicvalue > vertex2.heuristicvalue)
return 1;
return 0;
}
@Override
public boolean equals(Object obj)
{
if (obj instanceof Vertex)
{
Vertex node = (Vertex) obj;
if (this.node == node.node)
{
return true;
}
}
return false;
}
}
Output:
Enter the number of vertices
6
Enter the Weighted Matrix for the graph
0 0 1 1 0 1
0 0 0 1 1 1
1 0 0 1 0 0
1 1 1 0 1 0
0 1 0 1 0 0
1 1 0 0 0 0
Enter the heuristic values of the nodes
1.2
2.3
3.1
4.4
5.0
6.10
Enter the source
6
The graph is explored as follows
6 1 3 2 5 4
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