public int getRootFromNode(int nodeClassId) {
		if (classesMapNodeToRoot == null) {
			System.out.println("Ŀӳûи");
			return -1;
		} else {
			if (classesMapNodeToRoot.containsKey(nodeClassId)) {
				int rootClassId = (int) classesMapNodeToRoot.get(nodeClassId);
				return rootClassId;
			} else {
				System.out.print("ĿϵвcidΪ " + nodeClassId + " Ľڵ");
				return -1;
			}
		}
	}