Java Program to Find All Pairs Shortest Path

This Java program is to find all pairs shortest path.This program finds the shortest distance between every pair of vertex in the graph.

Here is the source code of the Java program to find all pairs shortest path. The Java program is successfully compiled and run on a Linux system. The program output is also shown below.

import java.util.Scanner;
 
public class AllPairShortestPath
{
    private int distancematrix[][];
    private int numberofvertices;
    public static final int INFINITY = 999;
 
    public AllPairShortestPath(int numberofvertices)
    {
        distancematrix = new int[numberofvertices + 1][numberofvertices + 1];
        this.numberofvertices = numberofvertices;
    }
 
    public void allPairShortestPath(int adjacencymatrix[][])
    {
        for (int source = 1; source <= numberofvertices; source++)
        {
            for (int destination = 1; destination <= numberofvertices; destination++)
            {
                distancematrix[destination] = adjacencymatrix[destination];
            }
        }
 
        for (int intermediate = 1; intermediate <= numberofvertices; intermediate++)
        {
            for (int source = 1; source <= numberofvertices; source++)
            {
                for (int destination = 1; destination <= numberofvertices; destination++)
                {
                    if (distancematrix[intermediate] + distancematrix[intermediate][destination]
                                         < distancematrix[destination])
                        distancematrix[destination] = distancematrix[intermediate] 
                                         + distancematrix[intermediate][destination];
                }
            }
        }
 
        for (int source = 1; source <= numberofvertices; source++)
            System.out.print("\t" + source);
 
        System.out.println();
        for (int source = 1; source <= numberofvertices; source++)
        {
            System.out.print(source + "\t");
            for (int destination = 1; destination <= numberofvertices; destination++)
            {
                System.out.print(distancematrix[destination] + "\t");
            }
            System.out.println();
        }
    }
 
    public static void main(String... arg)
    {
        int adjacency_matrix[][];
        int numberofvertices;
 
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter the number of vertices");
        numberofvertices = scan.nextInt();
 
        adjacency_matrix = new int[numberofvertices + 1][numberofvertices + 1];
        System.out.println("Enter the Weighted Matrix for the graph");
        for (int source = 1; source <= numberofvertices; source++)
        {
            for (int destination = 1; destination <= numberofvertices; destination++)
            {
                adjacency_matrix[destination] = scan.nextInt();
                if (source == destination)
                {
                    adjacency_matrix[destination] = 0;
                    continue;
                }
                if (adjacency_matrix[destination] == 0)
                {
                    adjacency_matrix[destination] = INFINITY;
                }
            }
        }
 
        System.out.println("The Transitive Closure of the Graph");
        AllPairShortestPath allPairShortestPath= new AllPairShortestPath(numberofvertices);
        allPairShortestPath.allPairShortestPath(adjacency_matrix);
 
        scan.close();
    }
}

$javac AllPairShortestPath.java
$java AllPairShortestPath
 
Enter the number of vertices
4
 
Enter the Weighted Matrix for the graph
0 0 3 0
2 0 0 0 
0 7 0 1
6 0 0 0
 
The Transitive Closure of the Graph
 
	1	2	3	4
1	0	10	3	4	
2	2	0	5	6	
3	7	7	0	1	
4	6	16	9	0