Dijkstra算法

package dijkstra;/** * 顶点 * @author victor * */public class Point {  public Point(String id) {    this.id = id;  }  public String getId() {    return id;  }  public void setId(String id) {    this.id = id;  }  @Override  public String toString() {    return id;  }  @Override  public int hashCode() {    return id.hashCode();  }  @Override  public boolean equals(Object obj) {    if (!(obj instanceof Point)) {      return false;    } else {      return ((Point) obj).id.equals(id);    }  }  private String id;}

package dijkstra;/** * 边界 * @author victor * */public class Border {  public Border(Point a, Point b) {    this.a = a;    this.b = b;  }  @Override  public int hashCode() {    return a.hashCode() + b.hashCode();  }  @Override  public boolean equals(Object obj) {    if (!(obj instanceof Border)) {      return false;    } else {      Border border = (Border) obj;      return border.a.equals(a) && border.b.equals(b);    }  }  @Override  public String toString() {    return "<" + a.toString() + "," + b.toString() + ">";  }  public Point getA() {    return a;  }  public void setA(Point a) {    this.a = a;  }  public Point getB() {    return b;  }  public void setB(Point b) {    this.b = b;  }  private Point a;  private Point b;}

package dijkstra;import java.util.HashMap;import java.util.ArrayList;import java.util.List;import java.util.Map;/** * Dijkstar * @author victor * */public class Dijkstra {  public static void main(String[] args) {    List<Point> points = new ArrayList<>();    for (int i = 0; i < 6; i++) {      char[] chars = {(char) ('A' + i)};      points.add(new Point(new String(chars)));    }    List<Border> borders = new ArrayList<>();    Map<Border, Integer> weights = new HashMap<>();    borders.add(new Border(points.get(0), points.get(1)));    borders.add(new Border(points.get(1), points.get(0)));    weights.put(borders.get(0), 6);    weights.put(borders.get(1), 6);    borders.add(new Border(points.get(0), points.get(2)));    borders.add(new Border(points.get(2), points.get(0)));    weights.put(borders.get(2), 3);    weights.put(borders.get(3), 3);    borders.add(new Border(points.get(2), points.get(1)));    borders.add(new Border(points.get(1), points.get(2)));    weights.put(borders.get(4), 2);    weights.put(borders.get(5), 2);    borders.add(new Border(points.get(2), points.get(4)));    borders.add(new Border(points.get(4), points.get(2)));    weights.put(borders.get(6), 4);    weights.put(borders.get(7), 4);    borders.add(new Border(points.get(2), points.get(3)));    borders.add(new Border(points.get(3), points.get(2)));    weights.put(borders.get(8), 3);    weights.put(borders.get(9), 3);    borders.add(new Border(points.get(1), points.get(3)));    borders.add(new Border(points.get(3), points.get(1)));    weights.put(borders.get(10), 5);    weights.put(borders.get(11), 5);    borders.add(new Border(points.get(3), points.get(4)));    borders.add(new Border(points.get(4), points.get(3)));    weights.put(borders.get(12), 2);    weights.put(borders.get(13), 2);    borders.add(new Border(points.get(3), points.get(5)));    borders.add(new Border(points.get(5), points.get(3)));    weights.put(borders.get(14), 3);    weights.put(borders.get(15), 3);    borders.add(new Border(points.get(4), points.get(5)));    borders.add(new Border(points.get(5), points.get(4)));    weights.put(borders.get(16), 5);    weights.put(borders.get(17), 5);    mid(points, borders, weights);    System.out.println(minRoutes);  }  public static void mid(List<Point> points, List<Border> borders, Map<Border, Integer> weights) {    Point zeroPoint = points.get(0);    minRoutes.put(new Border(zeroPoint, zeroPoint), 0);    List<Point> selectedPoints = new ArrayList<>();    selectedPoints.add(zeroPoint);    points = points.subList(1, points.size());    // initialization    for (Border border : borders) {      Point a = border.getA();      Point b = border.getB();      assemblePointLinkers(a, b, pointLinkers);    }    Point head = null;    for (; points.size() > 0; points.remove(0)) {      head = points.get(0);      List<Point> linkersOfHead = pointLinkers.get(head);      List<Point> selectedLinkersOfHead = new ArrayList<>();      for (Point point : linkersOfHead) {        if (selectedPoints.contains(point)) {          selectedLinkersOfHead.add(point);        }      }      Border newMinBorderForHead = new Border(zeroPoint, head);      int value = 0;      boolean unassigned = true;      for (Point point : selectedLinkersOfHead) {        int min =            minRoutes.get(new Border(zeroPoint, point)) + weights.get(new Border(point, head));        if (unassigned) {          value = min;          unassigned = false;        } else {          value = value > min ? min : value;        }      }      minRoutes.put(newMinBorderForHead, value);      selectedPoints.add(head);    }  }  private static void assemblePointLinkers(Point a, Point b, Map<Point, List<Point>> pointLinkers) {    if (!pointLinkers.containsKey(a)) {      List<Point> lists = new ArrayList<>();      lists.add(b);      pointLinkers.put(a, lists);    } else {      List<Point> lists = pointLinkers.get(a);      lists.add(b);    }  }  private static Map<Point, List<Point>> pointLinkers = new HashMap<>();  private static Map<Border, Integer> minRoutes = new HashMap<>();}