prims (1)

import java.util.Scanner;
 
class PrimsAlgorithm {
    private static int V;
 
    int minKey(int key[], boolean mstSet[]) {
        int min = Integer.MAX_VALUE, minIndex = -1;
        for (int v = 0; v < V; v++) {
            if (!mstSet[v] && key[v] < min) {
                min = key[v];
                minIndex = v;
            }
        }
        return minIndex;
    }
 
    void printMST(int parent[], int graph[][]) {
        int totalCost = 0;
        System.out.println("Edge \tWeight");
        for (int i = 1; i < V; i++) {
            System.out.println(parent[i] + " - " + i + "\t" + graph[i][parent[i]]);
            totalCost += graph[i][parent[i]];
        }
        System.out.println("Total cost of the MST: " + totalCost);
    }
 
    void primMST(int graph[][]) {
        int parent[] = new int[V];
        int key[] = new int[V];
        boolean mstSet[] = new boolean[V];
 
        for (int i = 0; i < V; i++) {
            key[i] = Integer.MAX_VALUE;
            mstSet[i] = false;
        }
 
        key[0] = 0;
        parent[0] = -1;
 
        for (int count = 0; count < V - 1; count++) {
            int u = minKey(key, mstSet);
            mstSet[u] = true;
 
            for (int v = 0; v < V; v++) {
                if (graph[u][v] != 0 && !mstSet[v] && graph[u][v] < key[v]) {
                    parent[v] = u;
                    key[v] = graph[u][v];
                }
            }
        }
 
        printMST(parent, graph);
    }
 
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
 
        System.out.print("Enter the number of vertices: ");
        V = scanner.nextInt();
 
        int[][] graph = new int[V][V];
 
        System.out.println("Enter the adjacency matrix (enter 0 if there is no edge between two vertices):");
        for (int i = 0; i < V; i++) {
            for (int j = 0; j < V; j++) {
                graph[i][j] = scanner.nextInt();
            }
        }
 
        PrimsAlgorithm t = new PrimsAlgorithm();
        t.primMST(graph);
 
        scanner.close();
    }
}
/*2 0 6 0
2 0 3 8 5
0 3 0 0 7
6 8 0 0 9
0 5 7 9 0
Edge 	Weight
0 - 1	2
1 - 2	3
0 - 3	6
1 - 4	5
Total cost of the MST: 16