public static void s(Node node){
	if(node == null){
		return ; 
	}
	Queue<Node> queue = new LinkedList();
	HashSet<Node> hashset = new HashSet();
	queue.add(node);
	hashset.add(node);
	while(!queue.isEmpty()){
		Node help = queue.poll(); 
		for(Node next : help.nexts){
			if(!hashset.contains(next)){
				queue.add(next);
				hashset.add(next) 
			}
		}
	}
}