Chapter 28 Exercise 12, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

28.12 (Variation of the nine tails problem) In the nine tails problem, when you flip a coin, the horizontal and vertical neighboring cells are also flipped. Rewrite the program, assuming that all neighboring cells including the diagonal neighbors are also flipped.

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

import javax.swing.*;

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

public class Exercise12 extends JApplet {

 private static final long serialVersionUID = 1L;
 private NineTailPanel nineTailPanel = new NineTailPanel();
 private JPanel jPanel1 = new JPanel(new FlowLayout());
 
 public Exercise12() {
  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("Exercise12");
  JApplet applet = new Exercise12();
  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);
   flipACell(node, row + 1, column + 1);
   flipACell(node, row + 1, column - 1);
   flipACell(node, row - 1, column - 1);
   flipACell(node, row - 1, 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);
 }

}