public class Graph<E> {
    /* You must use the following maps in your implementation */
    private HashMap<String, HashMap<String, Integer>> adjacencyMap;
    private HashMap<String, E> dataMap;

    private class Node{
        int weight;
        String prev;

        private Node(String predecessor, int cost){
            this.prev = predecessor;
            this.weight = cost;
        }

        private void setPrev(String name, int cost){
            this.prev = name;
            this.weight = cost;
        }

        private int getWeight(){
            return this.weight;

        }

        private String getPrev(){
            return this.prev;
        }
    }


    public Graph(){
        this.adjacencyMap = new HashMap<String, HashMap<String, Integer>>();
        this.dataMap = new HashMap<String, E>();


    }

    public void addVertex(String vertexName, E data){

        if(this.adjacencyMap.containsKey(vertexName)){
            throw new IllegalArgumentException("Already a vertex");

        }

        this.adjacencyMap.put(vertexName, new HashMap<String, Integer>());
        this.dataMap.put(vertexName, data);
    }

    public void addDirectedEdge(String startVertexName, String endVertexName, int cost){
        if(this.adjacencyMap.containsKey(startVertexName) == false ||
                this.adjacencyMap.containsKey(endVertexName) == false){

            throw new IllegalArgumentException("Check if vertex is in the graph");
        }

        this.adjacencyMap.get(startVertexName).put(endVertexName, cost);
    }

    public Map<String, Integer> getAdjacentVertices(String vertexName){
        return this.adjacencyMap.get(vertexName);

    }

    public int getCost(String startVertex, String endVertex){
        return this.adjacencyMap.get(startVertex).get(endVertex);

    }

    public E getData(String vertex){
        if(this.adjacencyMap.containsKey(vertex) == false){
            throw new IllegalArgumentException("No vertex with that name");

        }

        return this.dataMap.get(vertex);

    }

    public Set<String> getVertices(){
        return this.adjacencyMap.keySet();

    }