public static void getCriticalSet(ArrayList<Integer> res,
			ArrayList<Integer> critSet) {
		int numberDisconnect = 0;
		for (Integer vo : res) {
			for (Integer vi : res) {
				if (vo != vi && disconnect(vo, vi))
					numberDisconnect++;
			}
			// 有些节点已经是边界了，新加的节点必须和这些节点都相连
			if (numberDisconnect == k_plex - 1)
				critSet.add(vo);
			numberDisconnect = 0;// 复位
		}
	}