FloydWarshall.java

public class FloydWarshall {
    final static int INF = 99999, V = 4;

    void floydWarshall(int graph[][]) {
        int dist[][] = new int[V][V];
        int i, j, k;

        // Initialize the solution matrix same as input graph matrix
        for (i = 0; i < V; i++)
            for (j = 0; j < V; j++)
                dist[i][j] = graph[i][j];

        // Add all vertices one by one to the set of intermediate vertices
        for (k = 0; k < V; k++) {
            // Pick all vertices as source one by one
            for (i = 0; i < V; i++) {
                // Pick all vertices as destination for the above picked source
                for (j = 0; j < V; j++) {
                    // If vertex k is on the shortest path from i to j, then update the value of dist[i][j]
                    if (dist[i][k] + dist[k][j] < dist[i][j])
                        dist[i][j] = dist[i][k] + dist[k][j];
                }
            }
        }

        // Print the shortest distance matrix
        printSolution(dist);
    }

    void printSolution(int dist[][]) {
        System.out.println("The following matrix shows the shortest distances between every pair of vertices:");
        for (int i = 0; i < V; i++) {
            for (int j = 0; j < V; j++) {
                if (dist[i][j] == INF)
                    System.out.print("INF ");
                else
                    System.out.print(dist[i][j] + "   ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        /* Let us create the following weighted graph
               10
          (0)------->(3)
           |         /|\
         5 |          |
           |          | 1
          \|/         |
          (1)------->(2)
               3           */
        int graph[][] = { {0, 5, INF, 10},
                          {INF, 0, 3, INF},
                          {INF, INF, 0, 1},
                          {INF, INF, INF, 0} };
        FloydWarshall a = new FloydWarshall();

        // Print the solution
        a.floydWarshall(graph);
    }
}