Java Program to Find All Pairs Shortest Path

Code:

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[source][destination] = adjacencymatrix[source][destination];
            }
        }

        for (int intermediate = 1; intermediate <= numberofvertices; intermediate++)
        {
            for (int source = 1; source <= numberofvertices; source++)
            {
                for (int destination = 1; destination <= numberofvertices; destination++)
                {
                    if (distancematrix[source][intermediate] + distancematrix[intermediate][destination]
                                         < distancematrix[source][destination])
                        distancematrix[source][destination] = distancematrix[source][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[source][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[source][destination] = scan.nextInt();
                if (source == destination)
                {
                    adjacency_matrix[source][destination] = 0;
                    continue;
                }
                if (adjacency_matrix[source][destination] == 0)
                {
                    adjacency_matrix[source][destination] = INFINITY;
                }
            }
        }

        System.out.println("The Transitive Closure of the Graph");
        AllPairShortestPath allPairShortestPath= new AllPairShortestPath(numberofvertices);
        allPairShortestPath.allPairShortestPath(adjacency_matrix);

        scan.close();
    }
}


Output:

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



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