Dijkstra.java

/*
this program is used to find minimum distance between two vertices while traversing all available vertices.
 */
package javacodes;

import java.util.*;

public class Dijkstra {

    static int V;

    int minDistance(int dist[], Boolean que[]) {

        int min = Integer.MAX_VALUE, index = -1;

        for (int i = 0; i < V; i++) {
            if (que[i] == false && dist[i] <= min) {
                min = dist[i];

                index = i;
            }
        }

        return index;
    }

    void printSolution(int dist[], int n) // It displays Vertex Distance from Source
    {
        System.out.println("Vertex   Distance from Source");

        for (int i = 0; i < V; i++) {
            System.out.println(i + " \t\t " + dist[i]);
        }
    }

    void dijkstra(int graph[][], int src) {
        int dist[] = new int[V];

        Boolean que[] = new Boolean[V];

        for (int i = 0; i < V; i++) {
            dist[i] = Integer.MAX_VALUE;

            que[i] = false;
        }

        dist[src] = 0;
        /* Starting distance is zero */


        for (int count = 0; count < V - 1; count++) {

            int u = minDistance(dist, que);

            que[u] = true;

            for (int i = 0; i < V; i++) {
                if (!que[i] && graph[u][i] != 0
                        && dist[u] != Integer.MAX_VALUE
                        && dist[u] + graph[u][i] < dist[i]) {
                    dist[i] = dist[u] + graph[u][i];
                }
            }

        }

        printSolution(dist, V);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        System.out.println("Number of vertices:");
        /* print the total numbers of vertices */

        V = in.nextInt();

        int[][] graph = new int[V][V];

        System.out.println("Rows and Column of matrix:");

        for (int i = 0; i < V; i++) {
            for (int j = 0; j < V; j++) {
                graph[i][j] = in.nextInt();
            }
        }
        Dijkstra ob = new Dijkstra();
        /* create new object of Dijkstra */

        ob.dijkstra(graph, 0);
    }
}