Chapter 28 Exercise 11, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

28.11 (Revise Listing 28.14, NineTail.java) The program in Listing 28.14 lets the user enter an input for the nine tails problem from the console and displays the result on the console. Write a program that lets the user set an initial state of the nine coins (see Figure 28.22a) and click the Solve button to display the solution, as shown in Figure 28.22b. Initially, the user can click the mouse button to flip a
coin. Set a red color on the flipped cells.

import java.util.ArrayList;
import java.util.List;

import javax.swing.*;

import java.awt.*;
import java.awt.event.*;

public class Exercise11 extends JApplet {

 private static final long serialVersionUID = 1L;
 private NineTailPanel nineTailPanel = new NineTailPanel();
 private JPanel jPanel1 = new JPanel(new FlowLayout());
 
 public Exercise11() {
  jPanel1.add(nineTailPanel);
  setLayout(new BorderLayout());
  add(jPanel1, BorderLayout.CENTER);
  JPanel jPanel2 = new JPanel(new FlowLayout());
  JButton jButton1 = new JButton("Solve");
  JButton jButton2 = new JButton("Start Over");
  jPanel2.add(jButton1);
  jPanel2.add(jButton2);
  add(jPanel2, BorderLayout.SOUTH);
  jButton1.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    char[] initialNode = nineTailPanel.getInitialNode();


    NineTailModel model = new NineTailModel();
    java.util.List<Integer> path = model.getShortestPath(NineTailModel.getIndex(initialNode));

    for (int i = 1; i < path.size(); i++) {
     jPanel1.add(new NineTailPanel(NineTailModel.getNode(path.get(i).intValue()), NineTailModel.getNode(path.get(i - 1).intValue())));
    }
    jPanel1.updateUI();
   }
  });
  jButton2.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent e) {
    jPanel1.removeAll();
    nineTailPanel = new NineTailPanel();
    jPanel1.add(nineTailPanel);
    jPanel1.updateUI();
   }
  });
 }

 static class NineTailPanel extends JPanel {
  private static final long serialVersionUID = 1L;
  private int matrixSize = 3;
  private int coinSize = 50;
  private char[] initialNode = new char[matrixSize * matrixSize];
  private char[] previous = new char[matrixSize * matrixSize];
  
  public NineTailPanel() {
   for (int i = 0; i < initialNode.length; i++) {
    initialNode[i] = 'H';
   }
   previous = null;
   addMouseListener(new MouseAdapter() {
    
    @Override
    public void mouseReleased(MouseEvent e) {
     changeState((e.getX() / coinSize) * matrixSize + (e.getY() / coinSize));
    }
   });
  }
  
  public NineTailPanel(char[] initialNode, char[] previous) {
   for (int i = 0; i < initialNode.length; i++) {
    this.initialNode[i] = initialNode[i];
    this.previous[i] = previous[i];
   }
  }
  
  public char[] getInitialNode() {
   return initialNode;
  }
  
  void changeState(int i) {
   if(initialNode[i] == 'H') {
    initialNode[i] = 'T';
   } else {
    initialNode[i] = 'H';
   }
   repaint();
  }
  
  @Override
  protected void paintComponent(Graphics g) {
   super.paintComponent(g);
   g.setFont(new Font("Monospaced", Font.BOLD, 26));
   for (int i = 0; i < matrixSize; i++) {
    for (int j = 0; j < matrixSize; j++) {
     g.drawRect(i * coinSize, j * coinSize, coinSize, coinSize);
     if((previous != null) && (initialNode[i * matrixSize + j] != previous[i * matrixSize + j])) {
      g.setColor(Color.RED);
      g.drawString(initialNode[i * matrixSize + j] + "", i * coinSize + coinSize / 3, j * coinSize + 2 * (coinSize / 3));
      g.setColor(Color.BLACK);
     } else {
      g.drawString(initialNode[i * matrixSize + j] + "", i * coinSize + coinSize / 3, j * coinSize + 2 * (coinSize / 3));
     }
    }
   }
   
  }
  
  @Override
  public Dimension getPreferredSize() {
   return new Dimension(matrixSize * coinSize + 1, matrixSize * coinSize + 1);
  }

 }

 public static void main(String[] args) {
  JFrame frame = new JFrame("Exercise11");
  JApplet applet = new Exercise11();
  frame.add(applet);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setSize(800, 500);
  frame.setMinimumSize(new Dimension(frame.getWidth(), frame.getHeight()));
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
 }

 static class NineTailModel {
  public final static int NUMBER_OF_NODES = 512;
  protected AbstractGraph<Integer>.Tree tree; // Define a tree

  /** Construct a model */
  public NineTailModel() {
   // Create edges
   List<AbstractGraph.Edge> edges = getEdges();

   // Create a graph
   UnweightedGraph<Integer> graph = new UnweightedGraph<Integer>(
     edges, NUMBER_OF_NODES);

   // Obtain a BSF tree rooted at the target node
   tree = graph.bfs(511);
  }

  /** Create all edges for the graph */
  private List<AbstractGraph.Edge> getEdges() {
   List<AbstractGraph.Edge> edges = new ArrayList<AbstractGraph.Edge>(); // Store
                     // edges

   for (int u = 0; u < NUMBER_OF_NODES; u++) {
    for (int k = 0; k < 9; k++) {
     char[] node = getNode(u); // Get the node for vertex u
     if (node[k] == 'H') {
      int v = getFlippedNode(node, k);
      // Add edge (v, u) for a legal move from node u to node
      // v
      edges.add(new AbstractGraph.Edge(v, u));
     }
    }
   }

   return edges;
  }

  public static int getFlippedNode(char[] node, int position) {
   int row = position / 3;
   int column = position % 3;

   flipACell(node, row, column);
   flipACell(node, row - 1, column);
   flipACell(node, row + 1, column);
   flipACell(node, row, column - 1);
   flipACell(node, row, column + 1);

   return getIndex(node);
  }

  public static void flipACell(char[] node, int row, int column) {
   if (row >= 0 && row <= 2 && column >= 0 && column <= 2) {
    // Within the boundary
    if (node[row * 3 + column] == 'H')
     node[row * 3 + column] = 'T'; // Flip from H to T
    else
     node[row * 3 + column] = 'H'; // Flip from T to H
   }
  }

  public static int getIndex(char[] node) {
   int result = 0;

   for (int i = 0; i < 9; i++)
    if (node[i] == 'T')
     result = result * 2 + 1;
    else
     result = result * 2 + 0;

   return result;
  }

  public static char[] getNode(int index) {
   char[] result = new char[9];

   for (int i = 0; i < 9; i++) {
    int digit = index % 2;
    if (digit == 0)
     result[8 - i] = 'H';
    else
     result[8 - i] = 'T';
    index = index / 2;
   }

   return result;
  }

  public List<Integer> getShortestPath(int nodeIndex) {
   return tree.getPath(nodeIndex);
  }

  public static void printNode(char[] node) {
   for (int i = 0; i < 9; i++)
    if (i % 3 != 2)
     System.out.print(node[i]);
    else
     System.out.println(node[i]);

   System.out.println();
  }
 }

 static class UnweightedGraph<V> extends AbstractGraph<V> {
  /** Construct an empty graph */
  public UnweightedGraph() {
  }

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

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

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

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

 static abstract class AbstractGraph<V> implements Graph<V> {
  protected List<V> vertices = new ArrayList<V>(); // Store vertices
  protected List<List<Integer>> neighbors = new ArrayList<List<Integer>>(); // Adjacency
                     // lists

  /** Construct an empty graph */
  protected AbstractGraph() {
  }

  /** Construct a graph from edges and vertices stored in arrays */
  protected AbstractGraph(int[][] edges, V[] vertices) {
   for (int i = 0; i < vertices.length; i++)
    this.vertices.add(vertices[i]);

   createAdjacencyLists(edges, vertices.length);
  }

  /** Construct a graph from edges and vertices stored in List */
  protected AbstractGraph(List<Edge> edges, List<V> vertices) {
   for (int i = 0; i < vertices.size(); i++)
    this.vertices.add(vertices.get(i));

   createAdjacencyLists(edges, vertices.size());
  }

  /** Construct a graph for integer vertices 0, 1, 2 and edge list */
  @SuppressWarnings("unchecked")
  protected AbstractGraph(List<Edge> edges, int numberOfVertices) {
   for (int i = 0; i < numberOfVertices; i++)
    vertices.add((V) (new Integer(i))); // vertices is {0, 1, ...}

   createAdjacencyLists(edges, numberOfVertices);
  }

  /** Construct a graph from integer vertices 0, 1, and edge array */
  @SuppressWarnings("unchecked")
  protected AbstractGraph(int[][] edges, int numberOfVertices) {
   for (int i = 0; i < numberOfVertices; i++)
    vertices.add((V) (new Integer(i))); // vertices is {0, 1, ...}

   createAdjacencyLists(edges, numberOfVertices);
  }

  /** Create adjacency lists for each vertex */
  private void createAdjacencyLists(int[][] edges, int numberOfVertices) {
   // Create a linked list
   for (int i = 0; i < numberOfVertices; i++) {
    neighbors.add(new ArrayList<Integer>());
   }

   for (int i = 0; i < edges.length; i++) {
    int u = edges[i][0];
    int v = edges[i][1];
    neighbors.get(u).add(v);
   }
  }

  /** Create adjacency lists for each vertex */
  private void createAdjacencyLists(List<Edge> edges, int numberOfVertices) {
   // Create a linked list for each vertex
   for (int i = 0; i < numberOfVertices; i++) {
    neighbors.add(new ArrayList<Integer>());
   }

   for (Edge edge : edges) {
    neighbors.get(edge.u).add(edge.v);
   }
  }

  @Override
  /** Return the number of vertices in the graph */
  public int getSize() {
   return vertices.size();
  }

  @Override
  /** Return the vertices in the graph */
  public List<V> getVertices() {
   return vertices;
  }

  @Override
  /** Return the object for the specified vertex */
  public V getVertex(int index) {
   return vertices.get(index);
  }

  @Override
  /** Return the index for the specified vertex object */
  public int getIndex(V v) {
   return vertices.indexOf(v);
  }

  @Override
  /** Return the neighbors of the specified vertex */
  public List<Integer> getNeighbors(int index) {
   return neighbors.get(index);
  }

  @Override
  /** Return the degree for a specified vertex */
  public int getDegree(int v) {
   return neighbors.get(v).size();
  }

  @Override
  /** Print the edges */
  public void printEdges() {
   for (int u = 0; u < neighbors.size(); u++) {
    System.out.print(getVertex(u) + " (" + u + "): ");
    for (int j = 0; j < neighbors.get(u).size(); j++) {
     System.out.print("(" + u + ", " + neighbors.get(u).get(j)
       + ") ");
    }
    System.out.println();
   }
  }

  @Override
  /** Clear graph */
  public void clear() {
   vertices.clear();
   neighbors.clear();
  }

  @Override
  /** Add a vertex to the graph */
  public void addVertex(V vertex) {
   vertices.add(vertex);
   neighbors.add(new ArrayList<Integer>());
  }

  @Override
  /** Add an edge to the graph */
  public void addEdge(int u, int v) {
   neighbors.get(u).add(v);
   neighbors.get(v).add(u);
  }

  /** Edge inner class inside the AbstractGraph class */
  public static class Edge {
   public int u; // Starting vertex of the edge
   public int v; // Ending vertex of the edge

   /** Construct an edge for (u, v) */
   public Edge(int u, int v) {
    this.u = u;
    this.v = v;
   }
  }

  @Override
  /** Obtain a DFS tree starting from vertex v */
  /** To be discussed in Section 27.6 */
  public Tree dfs(int v) {
   List<Integer> searchOrder = new ArrayList<Integer>();
   int[] parent = new int[vertices.size()];
   for (int i = 0; i < parent.length; i++)
    parent[i] = -1; // Initialize parent[i] to -1

   // Mark visited vertices
   boolean[] isVisited = new boolean[vertices.size()];

   // Recursively search
   dfs(v, parent, searchOrder, isVisited);

   // Return a search tree
   return new Tree(v, parent, searchOrder);
  }

  /** Recursive method for DFS search */
  private void dfs(int v, int[] parent, List<Integer> searchOrder,
    boolean[] isVisited) {
   // Store the visited vertex
   searchOrder.add(v);
   isVisited[v] = true; // Vertex v visited

   for (int i : neighbors.get(v)) {
    if (!isVisited[i]) {
     parent[i] = v; // The parent of vertex i is v
     dfs(i, parent, searchOrder, isVisited); // Recursive search
    }
   }
  }

  @Override
  /** Starting bfs search from vertex v */
  /** To be discussed in Section 27.7 */
  public Tree bfs(int v) {
   List<Integer> searchOrder = new ArrayList<Integer>();
   int[] parent = new int[vertices.size()];
   for (int i = 0; i < parent.length; i++)
    parent[i] = -1; // Initialize parent[i] to -1

   java.util.LinkedList<Integer> queue = new java.util.LinkedList<Integer>(); // list
                      // used
                      // as
                      // a
                      // queue
   boolean[] isVisited = new boolean[vertices.size()];
   queue.offer(v); // Enqueue v
   isVisited[v] = true; // Mark it visited

   while (!queue.isEmpty()) {
    int u = queue.poll(); // Dequeue to u
    searchOrder.add(u); // u searched
    for (int w : neighbors.get(u)) {
     if (!isVisited[w]) {
      queue.offer(w); // Enqueue w
      parent[w] = u; // The parent of w is u
      isVisited[w] = true; // Mark it visited
     }
    }
   }

   return new Tree(v, parent, searchOrder);
  }

  /** Tree inner class inside the AbstractGraph class */
  /** To be discussed in Section 27.5 */
  public class Tree {
   private int root; // The root of the tree
   private int[] parent; // Store the parent of each vertex
   private List<Integer> searchOrder; // Store the search order

   /** Construct a tree with root, parent, and searchOrder */
   public Tree(int root, int[] parent, List<Integer> searchOrder) {
    this.root = root;
    this.parent = parent;
    this.searchOrder = searchOrder;
   }

   /** Return the root of the tree */
   public int getRoot() {
    return root;
   }

   /** Return the parent of vertex v */
   public int getParent(int v) {
    return parent[v];
   }

   /** Return an array representing search order */
   public List<Integer> getSearchOrder() {
    return searchOrder;
   }

   /** Return number of vertices found */
   public int getNumberOfVerticesFound() {
    return searchOrder.size();
   }

   /** Return the path of vertices from a vertex to the root */
   public List<V> getPath(int index) {
    ArrayList<V> path = new ArrayList<V>();

    do {
     path.add(vertices.get(index));
     index = parent[index];
    } while (index != -1);

    return path;
   }

   /** Print a path from the root to vertex v */
   public void printPath(int index) {
    List<V> path = getPath(index);
    System.out.print("A path from " + vertices.get(root) + " to "
      + vertices.get(index) + ": ");
    for (int i = path.size() - 1; i >= 0; i--)
     System.out.print(path.get(i) + " ");
   }

   /** Print the whole tree */
   public void printTree() {
    System.out.println("Root is: " + vertices.get(root));
    System.out.print("Edges: ");
    for (int i = 0; i < parent.length; i++) {
     if (parent[i] != -1) {
      // Display an edge
      System.out.print("(" + vertices.get(parent[i]) + ", "
        + vertices.get(i) + ") ");
     }
    }
    System.out.println();
   }
  }
 }

 interface Graph<V> {
  /** Return the number of vertices in the graph */
  public int getSize();

  /** Return the vertices in the graph */
  public java.util.List<V> getVertices();

  /** Return the object for the specified vertex index */
  public V getVertex(int index);

  /** Return the index for the specified vertex object */
  public int getIndex(V v);

  /** Return the neighbors of vertex with the specified index */
  public java.util.List<Integer> getNeighbors(int index);

  /** Return the degree for a specified vertex */
  public int getDegree(int v);

  /** Print the edges */
  public void printEdges();

  /** Clear graph */
  public void clear();

  /** Add a vertex to the graph */
  public void addVertex(V vertex);

  /** Add an edge to the graph */
  public void addEdge(int u, int v);

  /** Obtain a depth-first search tree */
  public AbstractGraph<V>.Tree dfs(int v);

  /** Obtain a breadth-first search tree */
  public AbstractGraph<V>.Tree bfs(int v);
 }

}