public class Solution {    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        if(node==null)            return null;        Map
     
       map=new HashMap
      
       ();        Queue
       
         que=new LinkedList
        
         ();        que.add(node);        map.put(node,new UndirectedGraphNode(node.label));        while(!que.isEmpty())        {            UndirectedGraphNode cur=que.poll();            for(UndirectedGraphNode child:cur.neighbors)            {                if(!map.containsKey(child))                {                    map.put(child, new UndirectedGraphNode(child.label));                    que.add(child);                }                map.get(cur).neighbors.add(map.get(child));            }        }        return map.get(node);    }}