Added BestFirstSearch in java

riktimmondal · riktimmondal · commit 4618f2f31c03 · 2017-10-06T11:26:13.000+05:30
diff --git a/BestFirstSearch/Java/Best_First_Search.java b/BestFirstSearch/Java/Best_First_Search.java
@@ -0,0 +1,162 @@
+import java.util.Comparator;
+import java.util.InputMismatchException;
+import java.util.PriorityQueue;
+import java.util.Scanner;
+ 
+public class BestFirstSearch
+{
+    private PriorityQueue<Vertex> 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<Vertex>(this.numberOfNodes,
+        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<Vertex>
+{
+    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;
+    }
+}
