DijkstraAlgo.java

/**
 * The DijkstraAlgo class implements Dijkstra's algorithm to find the shortest path from a source
 * vertex to all other vertices in a graph.
 */
import java.util.*;

class DijkstraAlgo {
    static final int V = 5;

    int minDistance(int dist[], Boolean sptSet[]) {
        int min = Integer.MAX_VALUE, min_index = -1;

        for (int v = 0; v < V; v++)
            if (sptSet[v] == false && dist[v] <= min) {
                min = dist[v];
                min_index = v;
            }

        return min_index;
    }

    void printSolution(int dist[]) {
        System.out.println("Vertex \t\t 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 sptSet[] = new Boolean[V];

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

        dist[src] = 0;

        for (int count = 0; count < V - 1; count++) {
            int u = minDistance(dist, sptSet);
            sptSet[u] = true;

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

        printSolution(dist);
    }

    public static void main(String[] args) {
        int graph[][] = new int[][] { { 0, 2, 0, 3, 0 },
                { 2, 0, 3, 0, 2 },
                { 0, 3, 0, 2, 0 },
                { 3, 0, 2, 0, 3 },
                { 0, 2, 0, 3, 0 } };
        DijkstraAlgo t = new DijkstraAlgo();
        t.dijkstra(graph, 0);
    }
}