This Java program,implements Best-First Search.Best-first search is a search algorithm which explores a graph by expanding the most promising node chosen according to a specified rule.
Judea Pearl described best-first search as estimating the promise of node n by a “heuristic evaluation function which, in general, may depend on the description of n, the description of the goal, the information gathered by the search up to that point, and most important, on any extra knowledge about the problem domain.
Here is the source code of the Java program to implements Best-First Search. The Java program is successfully compiled and run on a Linux system. The program output is also shown below.
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)); visited = 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; } }
$javac BestFirstSearch.java $java BestFirstSearch 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
Related posts:
Java Program to Implement Double Order Traversal of a Binary Tree
Changing Annotation Parameters At Runtime
So sánh ArrayList và LinkedList trong Java
Java Program to Implement LinkedTransferQueue API
Iterating over Enum Values in Java
Primitive Type Streams in Java 8
Injecting Prototype Beans into a Singleton Instance in Spring
Java Program to implement Array Deque
Java Program to Implement Max-Flow Min-Cut Theorem
Jackson – Unmarshall to Collection/Array
Java 9 Stream API Improvements
Introduction to PCollections
The Spring @Controller and @RestController Annotations
Java Program to Implement Segment Tree
Exploring the Spring Boot TestRestTemplate
Control Structures in Java
Java Program to Solve a Matching Problem for a Given Specific Case
Hướng dẫn sử dụng luồng vào ra nhị phân trong Java
Java Program to Find All Pairs Shortest Path
Guide to Apache Commons CircularFifoQueue
Composition, Aggregation, and Association in Java
Case-Insensitive String Matching in Java
Reading an HTTP Response Body as a String in Java
Java Program to Generate Randomized Sequence of Given Range of Numbers
Spring Boot - Rest Controller Unit Test
Java toString() Method
Java Program to Implement RoleList API
Spring Boot - Actuator
Java Program to Implement Stack API
Một số ký tự đặc biệt trong Java
Guide to UUID in Java
Flattening Nested Collections in Java