class Pair{

    int child,parent;

    Pair(int c,int p)

    {

        child = c;

        parent = p;

    }

}

class Solution {

    private static boolean help(ArrayList<ArrayList<Integer>> adj, int source, boolean []visited)

    {

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

        Pair p = new Pair(source,-1);

        queue.offer(p);

        while(!queue.isEmpty())

        {

            Pair x = queue.poll();

            int child = x.child;

            int parent = x.parent;

            visited[child] = true;

            ArrayList<Integer> l = adj.get(child);

            for(int ele : l)

            {

                if(!visited[ele])

                {

                    queue.offer(new Pair(ele,child));

                }

                else if(ele != parent)

                {

                    return true;

                }

            }

        }        

        return false;

    }

    // Function to detect cycle in an undirected graph.

    public boolean isCycle(int V, ArrayList<ArrayList<Integer>> adj) 

    {

        boolean[] visited = new boolean[V];

        for(int i=0;i<V;i++)

        {

            if(!visited[i])

            {

                if(help(adj,i,visited))

                {

                    return true;

                }

            }

        }

        return false;    

    }

}