import java.util.*;

public class graphSetMap {

//keys=Integer,values,neighbours=HashSet

HashMap<Integer,HashSet<Integer>> graph=new HashMap<>();

boolean addVertex(int vertex)

{

if(!graph.containsKey(vertex))

{

graph.put(vertex, new HashSet<>());

return true;

}

return false;

}

void addEdge(int u,int v)

{

//purane set ko vapis leke aane ke liye

// HashSet<Integer> neighbour=graph.get(u);

// neighbour.add(v);

// graph.put(u, neighbour);

graph.get(u).add(v);

//instead of upper 3 line

// neighbour=graph.get(v);

// neighbour.add(u);

// graph.put(v,neighbour);

graph.get(v).add(u);

}

void bfs(int s)

{

System.out.println("---------bfs----------");

HashSet<Integer> visited=new HashSet<>();

Queue<Integer> queue=new LinkedList<>();

queue.add(s);

visited.add(s);

while(!queue.isEmpty())

{

s = queue.poll();

System.out.println(s+" ");

for( Integer n:graph.get(s))

{

if(!visited.contains(n))

{

queue.add(n);

visited.add(n);

}

}

}

System.out.println();

}

void print()

{

//vertex shi print hogye

System.out.println(graph.keySet());

System.out.println();

for(Integer key:graph.keySet())

{

System.out.println("Adjaency List for Node: "+key);

System.out.println(graph.get(key));

}

}

public static void main(String[] args) {

graphSetMap g=new graphSetMap();

g.addVertex(0);

g.addVertex(1);

g.addVertex(2);

g.addVertex(3);

g.addVertex(4);

g.addEdge(0, 1);

g.addEdge(0, 2);

g.addEdge(0, 3);

//no error ,only copy of this element is store

// g.addEdge(0, 3);

g.addEdge(1,3);

g.addEdge(2,4);

g.addEdge(3,4);

g.print();

g.bfs(0);

}

}