In this problem you will implement Dijkstra's algorithm to find shortest paths between pairs of cities on a map. We are providing a a GUI that lets you visualize the map and the path your algorithm finds between two cities.

Before you start:

Download and unpack the file programming1.zip, which contains the GUI, a graph implementation, and data files representing a map. The file cityxy.txt contains a list of cities and their (X,Y) coordinates on the map. These are the vertices in the graph. The file citypairs.txt lists direct, connections between pairs of cities. These links are bidirectional, if you can from NewYork to Boston, you can get from Boston to NewYork. These are the edges of the graph.

If you use an IDE, import the java files and make sure that citxy.txt and citypairs.txt are placed in the project directory. If you use java and javac from the command line put the files in the same directory as the source files.

Compile all java sources and run the program Display. This should bring up a window and display the map. You will notice that clicking on "Compute All Euclidean Distances" does nothing and that "Draw Dijkstra's Path" will throw a null pointer exception on the terminal. You will have to implement these methods yourself.

Carefully read through the classes Vertex.java and Edge.java, which represent the vertices and edges of a graph. You will not have to modify these classes for the assignment, but you need to understand how the graph is represented and what information is associated with each vertex and edge. If you do modify these files, please explain in the README.

You will only have to modify Dijkstra.java, which represents a graph and will contain your implementation of Dijkstra's algorithm. You will need to use the instance variable vertexNames, which contains a mapping from city names to Vertex objects after the graph is read from the data files. The main method of Dijkstra illustrates how the class is used by the GUI and might be useful for testing your implementation on the command line.

a. Implement the method computeAllEuclideanDistances() which should compute the euclidean distance between all cities that have a direct link and set the weights for the corresponding edges in the graph. Once this works correctly, the correct distances should be displayed in the GUI when clicking on "Compute All Euclidean Distances".

b. In the method doDijkstra(String s), implement Dijkstra's algorithm starting at the city with name s. Use the distances associated with the edges. The method should update the distance and prev instance variables of the Vertex objects. You do not have to use a priority queue to store vertices that still need to be visited. Instead, keep these vertices on a list and scan through the entire list to find the minimum. We are making this simplification (at the expense of runtime) because java.util.PriorityQueue does not support the decreaseKey operation.

c. Implement the method getDijkstraPath(String s, String t), which first calls doDijstra(s) and then uses the distance and prev instance variables of the Vertex objects to find the shortest path between s and t. The resulting path should be returned as a list of Edge objects. Once this works correctly, you should be able to compute and display paths in the GUI.

import java.util.Collection; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.io.IOException; import java.io.FileReader; import java.io.BufferedReader;

public class Dijkstra {

// Keep a fast index to nodes in the map private Map vertexNames;

/** * Construct an empty Dijkstra with a map. The map's key is the name of a vertex * and the map's value is the vertex object. */ public Dijkstra() { vertexNames = new HashMap(); }

/** * Adds a vertex to the dijkstra. Throws IllegalArgumentException if two vertices * with the same name are added. * * @param v * (Vertex) vertex to be added to the dijkstra */ public void addVertex(Vertex v) { if (vertexNames.containsKey(v.name)) throw new IllegalArgumentException("Cannot create new vertex with existing name."); vertexNames.put(v.name, v); }

/** * Gets a collection of all the vertices in the dijkstra * * @return (Collection) collection of all the vertices in the dijkstra */ public Collection getVertices() { return vertexNames.values(); }

/** * Gets the vertex object with the given name * * @param name * (String) name of the vertex object requested * @return (Vertex) vertex object associated with the name */ public Vertex getVertex(String name) { return vertexNames.get(name); }

/** * Adds a directed edge from vertex u to vertex v * * @param nameU * (String) name of vertex u * @param nameV * (String) name of vertex v * @param cost * (double) cost of the edge between vertex u and v */ public void addEdge(String nameU, String nameV, Double cost) { if (!vertexNames.containsKey(nameU)) throw new IllegalArgumentException(nameU + " does not exist. Cannot create edge."); if (!vertexNames.containsKey(nameV)) throw new IllegalArgumentException(nameV + " does not exist. Cannot create edge."); Vertex sourceVertex = vertexNames.get(nameU); Vertex targetVertex = vertexNames.get(nameV); Edge newEdge = new Edge(sourceVertex, targetVertex, cost); sourceVertex.addEdge(newEdge); }

/** * Adds an undirected edge between vertex u and vertex v by adding a directed * edge from u to v, then a directed edge from v to u * * @param nameU * (String) name of vertex u * @param nameV * (String) name of vertex v * @param cost * (double) cost of the edge between vertex u and v */ public void addUndirectedEdge(String nameU, String nameV, double cost) { addEdge(nameU, nameV, cost); addEdge(nameV, nameU, cost); }

// STUDENT CODE STARTS HERE

/** * Computes the euclidean distance between two points as described by their * coordinates * * @param ux * (double) x coordinate of point u * @param uy * (double) y coordinate of point u * @param vx * (double) x coordinate of point v * @param vy * (double) y coordinate of point v * @return (double) distance between the two points */ public double computeEuclideanDistance(double ux, double uy, double vx, double vy) { // TODO return 1.0; // Replace this }

/** * Calculates the euclidean distance for all edges in the map using the * computeEuclideanCost method. */ public void computeAllEuclideanDistances() { // TODO }

/** * Dijkstra's Algorithm. * * @param s * (String) starting city name */ public void doDijkstra(String s) { // TODO }

/** * Returns a list of edges for a path from city s to city t. This will be the * shortest path from s to t as prescribed by Dijkstra's algorithm * * @param s * (String) starting city name * @param t * (String) ending city name * @return (List) list of edges from s to t */ public List getDijkstraPath(String s, String t) { doDijkstra(s);

// TODO return null; // Replace this }

// STUDENT CODE ENDS HERE

/** * Prints out the adjacency list of the dijkstra for debugging */ public void printAdjacencyList() { for (String u : vertexNames.keySet()) { StringBuilder sb = new StringBuilder(); sb.append(u); sb.append(" -> [ "); for (Edge e : vertexNames.get(u).adjacentEdges) { sb.append(e.target.name); sb.append("("); sb.append(e.distance); sb.append(") "); } sb.append("]"); System.out.println(sb.toString()); } }

/** * A main method that illustrates how the GUI uses Dijkstra.java to * read a map and represent it as a graph. * You can modify this method to test your code on the command line. */ public static void main(String[] argv) throws IOException { String vertexFile = "cityxy.txt"; String edgeFile = "citypairs.txt";

Dijkstra dijkstra = new Dijkstra(); String line;

// Read in the vertices BufferedReader vertexFileBr = new BufferedReader(new FileReader(vertexFile)); while ((line = vertexFileBr.readLine()) != null) { String[] parts = line.split(","); if (parts.length != 3) { vertexFileBr.close(); throw new IOException("Invalid line in vertex file " + line); } String cityname = parts[0]; int x = Integer.valueOf(parts[1]); int y = Integer.valueOf(parts[2]); Vertex vertex = new Vertex(cityname, x, y); dijkstra.addVertex(vertex); } vertexFileBr.close();

BufferedReader edgeFileBr = new BufferedReader(new FileReader(edgeFile)); while ((line = edgeFileBr.readLine()) != null) { String[] parts = line.split(","); if (parts.length != 3) { edgeFileBr.close(); throw new IOException("Invalid line in edge file " + line); } dijkstra.addUndirectedEdge(parts[0], parts[1], Double.parseDouble(parts[2])); } edgeFileBr.close();

// Compute distances. // This is what happens when you click on the "Compute All Euclidean Distances" button. dijkstra.computeAllEuclideanDistances(); // print out an adjacency list representation of the graph dijkstra.printAdjacencyList();

// This is what happens when you click on the "Draw Dijkstra's Path" button.

// In the GUI, these are set through the drop-down menus. String startCity = "SanFrancisco"; String endCity = "Boston";

// Get weighted shortest path between start and end city. List path = dijkstra.getDijkstraPath(startCity, endCity); System.out.print("Shortest path between "+startCity+" and "+endCity+": "); System.out.println(path); }

}

import java.awt.BasicStroke; import java.awt.Color; import java.awt.Desktop; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.Insets; import java.awt.RenderingHints; import java.awt.Stroke; import java.awt.event.ItemEvent; import java.awt.event.ItemListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.net.URI; import java.net.URISyntaxException; import java.util.HashMap; import java.util.LinkedList; import java.util.ArrayList; import java.util.List; import java.util.Collections;

import javax.swing.DefaultComboBoxModel; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JSeparator; import javax.swing.JTextField; import javax.swing.UIManager; import javax.swing.border.EmptyBorder;

@SuppressWarnings("serial") public class Display extends JFrame {

private JPanel contentPane; private JTextField txtCityxytxt; private JTextField txtCitypairstxt; private GraphPanel panel; private JComboBox weightedStartCityComboBox; private JComboBox weightedEndCityComboBox; private Dijkstra dijkstra; private JCheckBox chckbxShowEdgeWeights;

/** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { Display frame = new Display(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); }

public static Dijkstra readGraph(String vertexFile, String edgeFile) {

Dijkstra dijkstra = new Dijkstra(); try { String line; // Read in the vertices BufferedReader vertexFileBr = new BufferedReader(new FileReader(vertexFile)); while ((line = vertexFileBr.readLine()) != null) { String[] parts = line.split(","); if (parts.length != 3) { vertexFileBr.close(); throw new IOException("Invalid line in vertex file " + line); } String cityname = parts[0]; int x = Integer.valueOf(parts[1]); int y = Integer.valueOf(parts[2]); Vertex vertex = new Vertex(cityname, x, y); dijkstra.addVertex(vertex); } vertexFileBr.close(); // Now read in the edges BufferedReader edgeFileBr = new BufferedReader(new FileReader(edgeFile)); while ((line = edgeFileBr.readLine()) != null) { String[] parts = line.split(","); if (parts.length != 3) { edgeFileBr.close(); throw new IOException("Invalid line in edge file " + line); } dijkstra.addUndirectedEdge(parts[0], parts[1], Double.parseDouble(parts[2])); } edgeFileBr.close(); } catch (IOException e) { System.err.println("Could not read the dijkstra: " + e); return null; } return dijkstra; }

/** * Create the frame. */ public Display() { setTitle("Data Structures Dijkstra Visualizer"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(50, 50, 900, 700); setMinimumSize(new Dimension(800, 600)); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); GridBagLayout gbl_contentPane = new GridBagLayout(); gbl_contentPane.columnWidths = new int[] { 0, 0, 0, 0, 0, 0, 0 }; gbl_contentPane.rowHeights = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0 }; gbl_contentPane.columnWeights = new double[] { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, Double.MIN_VALUE }; gbl_contentPane.rowWeights = new double[] { 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE }; contentPane.setLayout(gbl_contentPane);

dijkstra = readGraph("cityxy.txt", "citypairs.txt");

panel = new GraphPanel(dijkstra); GridBagConstraints gbc_panel = new GridBagConstraints(); gbc_panel.gridwidth = 7; gbc_panel.insets = new Insets(0, 0, 7, 0); gbc_panel.fill = GridBagConstraints.BOTH; gbc_panel.gridx = 0; gbc_panel.gridy = 0; contentPane.add(panel, gbc_panel);

JSeparator separator = new JSeparator(); separator.setBackground(Color.WHITE); separator.setForeground(Color.GRAY); GridBagConstraints gbc_separator = new GridBagConstraints(); gbc_separator.fill = GridBagConstraints.BOTH; gbc_separator.gridwidth = 6; gbc_separator.insets = new Insets(0, 0, 5, 0); gbc_separator.gridx = 0; gbc_separator.gridy = 2; contentPane.add(separator, gbc_separator);

chckbxShowEdgeWeights = new JCheckBox("Show Edge Weights"); chckbxShowEdgeWeights.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent e) { repaint(); } });

JLabel lblReloadGraph = new JLabel("Load / Reload Dijkstra"); GridBagConstraints gbc_lblReloadGraph = new GridBagConstraints(); gbc_lblReloadGraph.anchor = GridBagConstraints.EAST; gbc_lblReloadGraph.insets = new Insets(0, 0, 5, 5); gbc_lblReloadGraph.gridx = 0; gbc_lblReloadGraph.gridy = 3; contentPane.add(lblReloadGraph, gbc_lblReloadGraph);

txtCityxytxt = new JTextField(); txtCityxytxt.setText("cityxy.txt"); GridBagConstraints gbc_txtCityxytxt = new GridBagConstraints(); gbc_txtCityxytxt.gridwidth = 2; gbc_txtCityxytxt.insets = new Insets(0, 0, 5, 5); gbc_txtCityxytxt.fill = GridBagConstraints.HORIZONTAL; gbc_txtCityxytxt.gridx = 1; gbc_txtCityxytxt.gridy = 3; contentPane.add(txtCityxytxt, gbc_txtCityxytxt); txtCityxytxt.setColumns(10);

txtCitypairstxt = new JTextField(); txtCitypairstxt.setText("citypairs.txt"); GridBagConstraints gbc_txtCitypairstxt = new GridBagConstraints(); gbc_txtCitypairstxt.gridwidth = 2; gbc_txtCitypairstxt.insets = new Insets(0, 0, 5, 5); gbc_txtCitypairstxt.fill = GridBagConstraints.HORIZONTAL; gbc_txtCitypairstxt.gridx = 3; gbc_txtCitypairstxt.gridy = 3; contentPane.add(txtCitypairstxt, gbc_txtCitypairstxt); txtCitypairstxt.setColumns(10);

JButton btnReloadGraph = new JButton("Load / Reset"); GridBagConstraints gbc_btnReloadGraph = new GridBagConstraints(); gbc_btnReloadGraph.fill = GridBagConstraints.HORIZONTAL; gbc_btnReloadGraph.insets = new Insets(0, 0, 5, 0); gbc_btnReloadGraph.gridx = 5; gbc_btnReloadGraph.gridy = 3; contentPane.add(btnReloadGraph, gbc_btnReloadGraph);

btnReloadGraph.addMouseListener(new MouseAdapter() { @Override public void mouseReleased(MouseEvent e) { // update JPanel updateGraphPanel(); } });

JLabel lblEuclideanCosts = new JLabel("Euclidean Costs"); GridBagConstraints gbc_lblEuclideanCosts = new GridBagConstraints(); gbc_lblEuclideanCosts.anchor = GridBagConstraints.EAST; gbc_lblEuclideanCosts.insets = new Insets(0, 0, 5, 5); gbc_lblEuclideanCosts.gridx = 0; gbc_lblEuclideanCosts.gridy = 4; contentPane.add(lblEuclideanCosts, gbc_lblEuclideanCosts); chckbxShowEdgeWeights.setSelected(true); GridBagConstraints gbc_chckbxShowEdgeWeights = new GridBagConstraints(); gbc_chckbxShowEdgeWeights.anchor = GridBagConstraints.EAST; gbc_chckbxShowEdgeWeights.gridwidth = 4; gbc_chckbxShowEdgeWeights.insets = new Insets(0, 0, 5, 5); gbc_chckbxShowEdgeWeights.gridx = 1; gbc_chckbxShowEdgeWeights.gridy = 4; contentPane.add(chckbxShowEdgeWeights, gbc_chckbxShowEdgeWeights);

JButton btnComputeAllEuclidean = new JButton("Compute All Euclidean Distances"); GridBagConstraints gbc_btnComputeAllEuclidean = new GridBagConstraints(); gbc_btnComputeAllEuclidean.fill = GridBagConstraints.BOTH; gbc_btnComputeAllEuclidean.insets = new Insets(0, 0, 5, 0); gbc_btnComputeAllEuclidean.gridx = 5; gbc_btnComputeAllEuclidean.gridy = 4; contentPane.add(btnComputeAllEuclidean, gbc_btnComputeAllEuclidean);

btnComputeAllEuclidean.addMouseListener(new MouseAdapter() { @Override public void mouseReleased(MouseEvent e) { panel.dijkstra.computeAllEuclideanDistances(); repaint(); } });

JLabel lblGetWeightedShortest_1 = new JLabel("Dijkstra's Algorithm"); GridBagConstraints gbc_lblGetWeightedShortest_1 = new GridBagConstraints(); gbc_lblGetWeightedShortest_1.anchor = GridBagConstraints.EAST; gbc_lblGetWeightedShortest_1.insets = new Insets(0, 0, 5, 5); gbc_lblGetWeightedShortest_1.gridx = 0; gbc_lblGetWeightedShortest_1.gridy = 5; contentPane.add(lblGetWeightedShortest_1, gbc_lblGetWeightedShortest_1);

JLabel lblStart_1 = new JLabel("Start"); GridBagConstraints gbc_lblStart_1 = new GridBagConstraints(); gbc_lblStart_1.insets = new Insets(0, 0, 5, 5); gbc_lblStart_1.anchor = GridBagConstraints.EAST; gbc_lblStart_1.gridx = 1; gbc_lblStart_1.gridy = 5; contentPane.add(lblStart_1, gbc_lblStart_1);

weightedStartCityComboBox = new JComboBox(); weightedStartCityComboBox.setToolTipText(""); GridBagConstraints gbc_weightedStartCityComboBox = new GridBagConstraints(); gbc_weightedStartCityComboBox.insets = new Insets(0, 0, 5, 5); gbc_weightedStartCityComboBox.fill = GridBagConstraints.HORIZONTAL; gbc_weightedStartCityComboBox.gridx = 2; gbc_weightedStartCityComboBox.gridy = 5; contentPane.add(weightedStartCityComboBox, gbc_weightedStartCityComboBox);

JLabel lblEnd_1 = new JLabel("End"); GridBagConstraints gbc_lblEnd_1 = new GridBagConstraints(); gbc_lblEnd_1.insets = new Insets(0, 0, 5, 5); gbc_lblEnd_1.anchor = GridBagConstraints.EAST; gbc_lblEnd_1.gridx = 3; gbc_lblEnd_1.gridy = 5; contentPane.add(lblEnd_1, gbc_lblEnd_1);

weightedEndCityComboBox = new JComboBox(); GridBagConstraints gbc_weightedEndCityComboBox = new GridBagConstraints(); gbc_weightedEndCityComboBox.insets = new Insets(0, 0, 5, 5); gbc_weightedEndCityComboBox.fill = GridBagConstraints.HORIZONTAL; gbc_weightedEndCityComboBox.gridx = 4; gbc_weightedEndCityComboBox.gridy = 5; contentPane.add(weightedEndCityComboBox, gbc_weightedEndCityComboBox);

JButton btnDrawWeightedShortest = new JButton("Draw Dijkstra's Path"); btnDrawWeightedShortest.setForeground(Color.GREEN); GridBagConstraints gbc_btnDrawWeightedShortest = new GridBagConstraints(); gbc_btnDrawWeightedShortest.fill = GridBagConstraints.HORIZONTAL; gbc_btnDrawWeightedShortest.insets = new Insets(0, 0, 5, 0); gbc_btnDrawWeightedShortest.gridx = 5; gbc_btnDrawWeightedShortest.gridy = 5; contentPane.add(btnDrawWeightedShortest, gbc_btnDrawWeightedShortest);

JLabel lblPanda = new JLabel("Panda 2016 "); lblPanda.setForeground(UIManager.getColor("TextField.light")); lblPanda.addMouseListener(new MouseAdapter() { @Override public void mouseReleased(MouseEvent e) { try { Desktop.getDesktop().browse(new URI("http://linanqiu.github.io/")); } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } catch (URISyntaxException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } });

JSeparator separator_1 = new JSeparator(); separator_1.setForeground(Color.GRAY); separator_1.setBackground(Color.WHITE); GridBagConstraints gbc_separator_1 = new GridBagConstraints(); gbc_separator_1.fill = GridBagConstraints.BOTH; gbc_separator_1.gridwidth = 6; gbc_separator_1.insets = new Insets(0, 0, 5, 0); gbc_separator_1.gridx = 0; gbc_separator_1.gridy = 6; contentPane.add(separator_1, gbc_separator_1); GridBagConstraints gbc_lblPanda = new GridBagConstraints(); gbc_lblPanda.gridwidth = 3; gbc_lblPanda.anchor = GridBagConstraints.EAST; gbc_lblPanda.gridx = 3; gbc_lblPanda.gridy = 7; contentPane.add(lblPanda, gbc_lblPanda);

btnDrawWeightedShortest.addMouseListener(new MouseAdapter() { @Override public void mouseReleased(MouseEvent e) { String startCity = weightedStartCityComboBox.getItemAt(weightedStartCityComboBox.getSelectedIndex()); String endCity = weightedEndCityComboBox.getItemAt(weightedEndCityComboBox.getSelectedIndex()); System.out.println("Calculating shortest weighted path for " + startCity + " to " + endCity); List weightedPath = dijkstra.getDijkstraPath(startCity, endCity); panel.overlayEdges.put("weighted", weightedPath); repaint(); } });

updateGraphPanel(); }

private void updateGraphPanel() { String vertexFile = txtCityxytxt.getText(); String edgeFile = txtCitypairstxt.getText(); dijkstra = readGraph(vertexFile, edgeFile); panel.dijkstra = dijkstra; System.out.println("Constructing new file from " + vertexFile + " and " + edgeFile); System.out.println("Data read: " + panel.dijkstra.getVertices());

List cityNameList = new ArrayList(); for (Vertex v : dijkstra.getVertices()) cityNameList.add(v.name); Collections.sort(cityNameList); String[] cityNames = cityNameList.toArray(new String[cityNameList.size()]); weightedStartCityComboBox.setModel(new DefaultComboBoxModel(cityNames)); weightedEndCityComboBox.setModel(new DefaultComboBoxModel(cityNames));

panel.overlayEdges.put("weighted", new LinkedList()); panel.overlayEdges.put("unweighted", new LinkedList()); panel.overlayEdges.put("mst", new LinkedList());

repaint(); }

public class GraphPanel extends JPanel {

// dijkstra layout parameters public static final int VERTEX_RADIUS = 10; public static final int SPACE = 3;

public static final int MARGIN_X = 50; public static final int MARGIN_Y = 50;

public static final int DEFAULT_THICKNESS = 1;

// scale factors public float xFactor, yFactor;

public Dijkstra dijkstra;

public HashMap> overlayEdges;

public GraphPanel(Dijkstra dijkstra) { this.dijkstra = dijkstra; overlayEdges = new HashMap(); overlayEdges.put("weighted", new LinkedList()); overlayEdges.put("unweighted", new LinkedList()); overlayEdges.put("mst", new LinkedList()); }

public void paintComponent(Graphics g) { // make everything smooth like butter Graphics2D g2 = (Graphics2D) g; g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); g2.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE); g2.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON); g2.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY); g2.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY); g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);

// scale the dijkstra int minX = 0; int maxX = 1; int minY = 0; int maxY = 1; for (Vertex v : dijkstra.getVertices()) { if (v.x maxX) maxX = v.x; if (v.y maxY) maxY = v.y; } xFactor = (this.getBounds().width - 2 * MARGIN_X) / (float) (maxX - minX); yFactor = (this.getBounds().height - 2 * MARGIN_Y) / (float) (maxY - minY); super.paintComponent(g2); // paint the panel try { paintGraph(g2); // paint the dijkstra } catch (NullPointerException e) { e.printStackTrace(); } }

public void paintGraph(Graphics g) { for (Vertex v : dijkstra.getVertices()) { for (Edge edge : v.adjacentEdges) { paintEdge(g, edge.source, edge.target, edge.distance, Color.LIGHT_GRAY, DEFAULT_THICKNESS, 255); } } for (Vertex v : dijkstra.getVertices()) { paintVertex(g, v); } for (String overlayType : overlayEdges.keySet()) { if (overlayType.equals("unweighted")) { for (Edge edge : overlayEdges.get(overlayType)) { paintEdge(g, edge.source, edge.target, edge.distance, Color.RED, 8, 50); } } if (overlayType.equals("weighted")) { for (Edge edge : overlayEdges.get(overlayType)) { paintEdge(g, edge.source, edge.target, edge.distance, Color.GREEN, 8, 50); } } if (overlayType.equals("mst")) { for (Edge edge : overlayEdges.get(overlayType)) { paintEdge(g, edge.source, edge.target, edge.distance, Color.BLUE, 8, 50); } } } }

public void paintVertex(Graphics g, Vertex v) { Graphics2D g2 = (Graphics2D) g;

int x = Math.round(xFactor * (float) v.x + (float) MARGIN_X); int y = Math.round(yFactor * (float) v.y + (float) MARGIN_Y); g2.setColor(Color.LIGHT_GRAY); Stroke oldStroke = g2.getStroke(); g2.setStroke(new BasicStroke(4)); g2.drawOval(x - VERTEX_RADIUS / 2, y - VERTEX_RADIUS / 2, VERTEX_RADIUS, VERTEX_RADIUS); g2.setStroke(oldStroke); g2.setColor(Color.LIGHT_GRAY); g2.fillOval(x - VERTEX_RADIUS / 2, y - VERTEX_RADIUS / 2, VERTEX_RADIUS, VERTEX_RADIUS); g2.setColor(Color.DARK_GRAY); g2.drawString(v.name, x - v.name.length() * 8 / 2, y + VERTEX_RADIUS / 2); }

public void paintEdge(Graphics g, Vertex u, Vertex v, double weight, Color color, int thickness, int alpha) { Graphics2D g2 = (Graphics2D) g; int x1 = Math.round(xFactor * (float) u.x + (float) MARGIN_X); int y1 = Math.round(yFactor * (float) u.y + (float) MARGIN_Y); int x2 = Math.round(xFactor * (float) v.x + (float) MARGIN_X); int y2 = Math.round(yFactor * (float) v.y + (float) MARGIN_Y); g2.setColor(new Color(color.getRed(), color.getGreen(), color.getBlue(), alpha)); Stroke oldStroke = g2.getStroke(); g2.setStroke(new BasicStroke(thickness)); g2.drawLine(x1, y1, x2, y2); g2.setStroke(oldStroke); if (chckbxShowEdgeWeights.isSelected()) { Font oldFont = g2.getFont(); g2.setFont(new Font("Helvetica", Font.PLAIN, 8)); g2.setColor(Color.GRAY); g2.drawString(String.format("%.1f", weight), (x1 + x2) / 2, (y1 + y2) / 2); g2.setFont(oldFont); } } } }

public class Edge {

public double distance;

public Vertex source;

public Vertex target;

public Edge(Vertex vertex1, Vertex vertex2, double weight) {

source = vertex1;

target = vertex2;

this.distance = weight;

}

public String toString() {

return source + " - " + target;

}

}

import java.util.LinkedList; import java.util.List;

public class Vertex {

public String name; public int x; public int y; public boolean known; public double distance; // total distance from origin point public Vertex prev; public List adjacentEdges;

public Vertex(String name, int x, int y) { this.name = name; this.x = x; this.y = y; // by default java sets uninitialized boolean to false and double to 0 // hence known == false and dist == 0.0 adjacentEdges = new LinkedList(); prev = null; }

@Override public int hashCode() { // we assume that each vertex has a unique name return name.hashCode(); }

@Override public boolean equals(Object o) { if (this == o) { return true; } if (o == null) { return false; } if (!(o instanceof Vertex)) { return false; } Vertex oVertex = (Vertex) o;

return name.equals(oVertex.name) && x == oVertex.x && y == oVertex.y; }

public void addEdge(Edge edge) { adjacentEdges.add(edge); }

public String toString() { return name + " (" + x + ", " + y + ")"; }

}

citypairs.txt

Vancouver,Calgary,100 Vancouver,Seattle,100 Calgary,Winnipeg,100 Calgary,Helena,100 Calgary,Seattle,100 Winnipeg,Helena,100 Winnipeg,Duluth,100 Winnipeg,SaultSaintMarie,100 SaultSaintMarie,Duluth,100 SaultSaintMarie,Toronto,100 SaultSaintMarie,Montreal,100 Toronto,Montreal,100 Toronto,Pittsburgh,100 Montreal,Boston,100 Montreal,NewYork,100 Seattle,Helena,100 Seattle,Portland,100 Helena,Duluth,100 Helena,SaltLakeCity,100 Helena,Denver,100 Helena,Omaha,100 Duluth,Omaha,100 Duluth,Chicago,100 Chicago,Pittsburgh,100 Chicago,SaintLouis,100 Chicago,Omaha,100 Pittsburgh,NewYork,100 Pittsburgh,Washington,100 NewYork,Washington,100 NewYork,Boston,100 Portland,SanFrancisco,100 Portland,SaltLakeCity,100 SanFrancisco,SaltLakeCity,100 SanFrancisco,LosAngeles,100 LosAngeles,LasVegas,100 LosAngeles,Phoenix,100 SaltLakeCity,Denver,100 SaltLakeCity,LasVegas,100 Denver,SantaFe,100 Denver,Phoenix,100 Denver,Omaha,100 Denver,KansasCity,100 KansasCity,SaintLouis,100 KansasCity,OklahomaCity,100 SaintLouis,Nashville,100 Nashville,Raleigh,100 Nashville,Atlanta,100 Washington,Raleigh,100 Raleigh,Atlanta,100 Raleigh,Charleston,100 Atlanta,Miami,100 Atlanta,NewOrleans,100 Charleston,Miami,100 Miami,NewOrleans,100 NewOrleans,LittleRock,100 NewOrleans,Houston,100 Houston,Dallas,100 Dallas,LittleRock,100 Dallas,ElPaso,100 ElPaso,LosAngeles,100 ElPaso,SantaFe,100 Atlanta,Charleston,100 SantaFe,OklahomaCity,100 SantaFe,Phoenix,100 LittleRock,Nashville,100 LittleRock,OklahomaCity,100 LittleRock,SaintLouis,100

cityxy.txt

Vancouver,80,78 Calgary,180,67 Winnipeg,360,75 Montreal,696,66 SaultSaintMarie,550,120 Seattle,76,123 Toronto,630,130 Boston,750,110 Portland,60,164 Helena,260,170 Duluth,440,166 NewYork,700,165 SaltLakeCity,200,270 Denver,300,290 Omaha,420,240 Chicago,540,215 Pittsburgh,640,200 Washington,716,240 SanFrancisco,50,315 KansasCity,435,280 SaintLouis,500,300 Raleigh,700,285 OklahomaCity,420,340 LittleRock,490,360 Nashville,580,330 LasVegas,160,350 SantaFe,300,360 Atlanta,640,360 Charleston,700,380 LosAngeles,111,395 Phoenix,220,390 ElPaso,300,425 Dallas,440,415 Houston,470,450 NewOrleans,550,440 Miami,700,460