Question

Write a java program to do BFS topological sort . your program must be able to catch the loop.

m у 2.

Answer 1

import java.util.*;

class grph { 
        int vrt;
        List<Integer> adj[]; 
        public grph(int vrt) 
        { 
                this.vrt = vrt; 
                adj = new ArrayList[vrt]; 
                for (int p= 0; p < vrt; p++) 
                        adj[p] = new ArrayList<Integer>(); 
        } 
        public void add(int u, int v) 
        { 
                adj[u].add(v); 
        } 
        public void BfsTopologicalSort() 
        { 
                int Indegree[] = new int[vrt]; 
                for (int p = 0; p < vrt; p++) { 
                        ArrayList<Integer> temp 
                                = (ArrayList<Integer>)adj[p]; 
                        for (int node : temp) { 
                                Indegree[node]++; 
                        } 
                } 
                Queue<Integer> q 
                        = new LinkedList<Integer>(); 
                for (int p = 0; p < vrt; p++) { 
                        if (Indegree[p] == 0) 
                                q.add(p); 
                } 
                int c = 0; 
                Vector<Integer> TopOrder = new Vector<Integer>(); 
                while (!q.isEmpty()) { 
                        int u = q.poll(); 
                        TopOrder.add(u); 

                        for (int node : adj[u]) { 
                                if (--Indegree[node] == 0) 
                                        q.add(node); 
                        } 
                        c++; 
                } 
                if (c != vrt) { 
                        System.out.println( 
                                "cycle iS PRESENT IN the graph"); 
                        return; 
                } 
                for (int p : TopOrder) { 
                        System.out.print(p + " "); 
                } 
        } 
} 
class Main { 
        public static void main(String args[]) 
        { 
                grph gp = new grph(14); 
                gp.add(12,9); 
                gp.add(10,13); 
                gp.add(9,11); 
                gp.add(9,10); 
                gp.add(8,7); 
                gp.add(6,5); 
                gp.add(5,12);
                gp.add(5,8);
                gp.add(4,7);
                gp.add(3,13);
                gp.add(3,6);
                gp.add(3,2);
                gp.add(2,6);
                gp.add(2,9);
                gp.add(2,5);
                gp.add(1,8);
                gp.add(1,4);
                gp.add(1,2);
                gp.add(0,11);
                gp.add(0,4);
                gp.add(0,5);
               
                System.out.println( 
                        "BFS _Topological Sort"); 
                gp.BfsTopologicalSort(); 
        } 
}

As per the program i assigned

edge m is taken 0

edge n is taken 1

edge o is taken 2

edge p is taken 3

edge q is taken 4

edge r is taken 5

edge s is taken 6

edge t is taken 7

edge u is taken 8

edge v is taken 9

edge w is taken 10

edge x is taken 11

edge y is taken 12

edge z is taken 13

please take accordingly bro and give me thumbs up