code: protected Node<V> arraivedNode(int number,int layout,Node<V> currentNode,boolean create)
  	{
  		if(layout<0)
  		{//超出范围
  			return null;
  		}
  		if(layout==0)
  		{
  			return currentNode;
  		}
  		layout--;
  		int p=getMaskValue(number,layout);
  		Node<V>[] sub=currentNode.getSub();
  		Node<V> node=sub[p];
  		if(node==null)
  		{
  			if(!create)
  			{//如果不是新建路径则返回null表示不可达
  				return null;
  			}
  			if(layout==0)
  			{//layout=0的node具有data属性
  				node=new DataNode<V>(number);
  			}else
  			{
  				node=buildLayOutNode();
  			}
  			sub[p]=node;
  		}
  		return arraivedNode(number, layout,node,create);
  	}
docs: 抵达节点
  @param number
  @param layout
  @param currentNode
  @return