/*
Refer https://www.geeksforgeeks.org/dijkstras-shortest-path-algorithm-greedy-algo-7/
for better understanding 
*/
package DataStructures.Graphs;

class dijkstras{

    int k=9;
    int minDist(int dist[], Boolean Set[])
    {
        int min = Integer.MAX_VALUE, min_index = -1;
 
        for (int r = 0; r < k; r++)
            if (Set[r] == false && dist[r] <= min) {
                min = dist[r];
                min_index = r;
            }
 
        return min_index;
    }

    void print(int dist[])
    {
        System.out.println("Vertex \t\t Distance");
        for (int i = 0; i < k; i++)
            System.out.println(i + " \t " + dist[i]);
    }
    void dijkstra(int graph[][], int src)
    {
        int dist[] = new int[k]; 
        Boolean Set[] = new Boolean[k];
 
        for (int i = 0; i < k; i++) {
            dist[i] = Integer.MAX_VALUE;
            Set[i] = false;
        }
 
        dist[src] = 0;
 
        for (int c = 0; c < k - 1; c++) {
           
            int u = minDist(dist, Set);
 
            Set[u] = true;
 
            for (int v = 0; v < k; v++)
 
                if (!Set[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v])
                    dist[v] = dist[u] + graph[u][v];
        }
 
        print(dist);
    }
 
    public static void main(String[] args)
    {
        int graph[][] = new int[][] { { 0, 4, 0, 0, 0, 0, 0, 8, 0 },
                                      { 4, 0, 8, 0, 0, 0, 0, 11, 0 },
                                      { 0, 8, 0, 7, 0, 4, 0, 0, 2 },
                                      { 0, 0, 7, 0, 9, 14, 0, 0, 0 },
                                      { 0, 0, 0, 9, 0, 10, 0, 0, 0 },
                                      { 0, 0, 4, 14, 10, 0, 2, 0, 0 },
                                      { 0, 0, 0, 0, 0, 2, 0, 1, 6 },
                                      { 8, 11, 0, 0, 0, 0, 1, 0, 7 },
                                      { 0, 0, 2, 0, 0, 0, 6, 7, 0 } };
        dijkstras t = new dijkstras();
        t.dijkstra(graph, 0);
    }//main

}//djikstras

/*
OUTPUT :
Vertex   Distance 
0            0
1            4
2            12
3            19
4            21
5            11
6            9
7            8
8            14
*/