import java.util.*;

/** A set of nodes */
public class Graph {
    /** Map a node name to the node */
    ... define nodes field here ...

    public Node addNode(String name) {
    }

    public void addEdge(String name, String target) {
    }

    /** Return sorted list of all nodes between start and stop, inclusively */
    public List<Node> getAllNodes(String start, String stop) {
        Set<Node> pathNodes = new HashSet<Node>();
        _getAllNodes(nodes.get(start), nodes.get(stop), pathNodes);
        List<Node> nodeList = new ArrayList<Node>(pathNodes);
        Collections.sort(nodeList);
        return nodeList;
    }

    protected boolean _getAllNodes(Node p, Node stop, Set<Node> pathNodes) {
    }

    public int getMinPathLength(String start, String stop) {
    }

    /** Return a sorted list of all nodes reachable from start, inclusively */
    public List<Node> getAllReachableNodes(String start) {
    }

    public List<String> getRootNames() {
    }

    /** Print out an edge list for graph */
    public String toString() {
    }
}