Database System Concepts
Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    Tree cannot be resolved to a type

    at Exercise28_05$UnweightedGraphWithGetPath.getPath(Exercise28_05.java:80)
    at Exercise28_05.<init>(Exercise28_05.java:35)
    at Exercise28_05.main(Exercise28_05.java:8)

Here is the part of my code that is experiencing issues:

import java.util.*;
import java.io.*;

public class Exercise28_05 
{
  public static void main(String[] args) throws Exception 
  {
    new Exercise28_05();
  }
  
  public Exercise28_05() throws Exception 
  {
    String[] vertices = { "Seattle", "San Francisco", "Los Angeles", "Denver",
        "Kansas City", "Chicago", "Boston", "New York", "Atlanta", "Miami",
        "Dallas", "Houston" };

    int[][] edges = { { 0, 1 }, { 0, 3 }, { 0, 5 }, { 1, 0 }, { 1, 2 },
        { 1, 3 }, { 2, 1 }, { 2, 3 }, { 2, 4 }, { 2, 10 }, { 3, 0 }, { 3, 1 },
        { 3, 2 }, { 3, 4 }, { 3, 5 }, { 4, 2 }, { 4, 3 }, { 4, 5 }, { 4, 7 },
        { 4, 8 }, { 4, 10 }, { 5, 0 }, { 5, 3 }, { 5, 4 }, { 5, 6 }, { 5, 7 },
        { 6, 5 }, { 6, 7 }, { 7, 4 }, { 7, 5 }, { 7, 6 }, { 7, 8 }, { 8, 4 },
        { 8, 7 }, { 8, 9 }, { 8, 10 }, { 8, 11 }, { 9, 8 }, { 9, 11 },
        { 10, 2 }, { 10, 4 }, { 10, 8 }, { 10, 11 }, { 11, 8 }, { 11, 9 },
        { 11, 10 } };

    UnweightedGraphWithGetPath<String> graph = new UnweightedGraphWithGetPath<>(
        vertices, edges);
    Scanner input = new Scanner(System.in);
    System.out.print("Enter a starting city: ");
    String startingCity = input.nextLine();

    System.out.print("Enter an ending city: ");
    String endingCity = input.nextLine();

    List<Integer> list = graph.getPath(graph.getIndex(startingCity),
        graph.getIndex(endingCity));

    System.out.print("The path is ");
    for (Integer i : list) 
    {
      System.out.print(graph.getVertex(i) + " ");
    }
  }

// BEGIN REVEL SUBMISSION
  class UnweightedGraphWithGetPath<V> extends UnweightedGraph<V> 
  {
    /** Construct an empty graph */
    public UnweightedGraphWithGetPath() 
    {
        
    }

    /** Construct a graph from vertices and edges stored in arrays */
    public UnweightedGraphWithGetPath(V[] vertices, int[][] edges) 
    {
      super(vertices, edges);
    }

    /** Construct a graph from vertices and edges stored in List */
    public UnweightedGraphWithGetPath(List<V> vertices, List<Edge> edges) 
    {
      super(vertices, edges);
    }

    /** Construct a graph for integer vertices 0, 1, 2 and edge list */
    public UnweightedGraphWithGetPath(List<Edge> edges, int numberOfVertices) 
    {
      super(edges, numberOfVertices);
    }

    /** Construct a graph from integer vertices 0, 1, and edge array */
    public UnweightedGraphWithGetPath(int[][] edges, int numberOfVertices) 
    {
      super(edges, numberOfVertices);
    }

    public List<Integer> getPath(int u, int v) 
    {
         Tree tree = bfs(u);
           ArrayList<Integer> path = new ArrayList<>();

           do 
           {
            path.add(v);
            v = tree.parent[v];
           } while (v != -1);

           Collections.reverse(path);
           return path;
    }
  }

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