public LinkedList<Node> expandNode() {
		LinkedList<Node> nodes = new LinkedList<Node>();
		for (Action action : state.getAdmissibleActions()) {
			PuzzleState copyState = new PuzzleState(getState());
			copyState.move(action);
			Node n = new Node(copyState, this, action);
			n.setG(this.g + 1);
			nodes.add(n);
		}
		return nodes;
	}