wip(marathon): algo
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package org.insa.graphs.algorithm.marathon;
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import java.util.ArrayList;
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import java.util.Collections;
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import org.insa.graphs.algorithm.AbstractAlgorithm;
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import org.insa.graphs.algorithm.AbstractSolution.Status;
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import org.insa.graphs.algorithm.shortestpath.Label;
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import org.insa.graphs.algorithm.shortestpath.ShortestPathData;
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import org.insa.graphs.algorithm.shortestpath.ShortestPathObserver;
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import org.insa.graphs.algorithm.shortestpath.ShortestPathSolution;
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import org.insa.graphs.algorithm.utils.BinaryHeap;
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import org.insa.graphs.model.Arc;
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import org.insa.graphs.model.Graph;
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import org.insa.graphs.model.Node;
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import org.insa.graphs.model.Path;
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public class MarathonAlgorithm extends AbstractAlgorithm<ShortestPathObserver> {
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protected double pathCost;
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protected MarathonAlgorithm(ShortestPathData data) {
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super(data);
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}
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@Override
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public ShortestPathSolution run() {
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return (ShortestPathSolution) super.run();
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}
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@Override
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protected ShortestPathSolution doRun() {
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final ShortestPathData data = getInputData();
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ShortestPathSolution solution = null;
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final Graph graph = data.getGraph();
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final int nbNodes = graph.size();
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// List of sommets, but with type Label
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ArrayList<Label> labels = new ArrayList<Label>(nbNodes);
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// Heap of sommets
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BinaryHeap<Label> tas = new BinaryHeap<Label>();
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// Notify observers about the first event (origin processed).
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notifyOriginProcessed(data.getOrigin());
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// Init Dijkstra
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for (Node node : graph.getNodes()) {
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// Luckily they are ordered by id.
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// ArrayList.set only works if the value is already initialized (because why Java?)
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labels.add(this.createLabel(node));
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}
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Label s = labels.get(data.getOrigin().getId());
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// Add origin in the heap
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// Label s = origin;//labels.get(0);
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s.setPathCost(0);
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tas.insert(s);
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// On considère le sommet x à chaque itération
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Label x = s;
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final int dest_id = data.getDestination().getId();
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while (!tas.isEmpty() && !(labels.get(dest_id).getNode().equals(x.getNode()))) {
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x = tas.deleteMin();
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x.mark();
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notifyNodeMarked(x.getNode());
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// System.out.println(x.getCost()); // Pour vérifier une croissance des noeuds marqués
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// We create a list of node successors of x, instead of a list of Arcs.
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double arc_cost = 0;
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for (Arc successorArc : x.getNode().getSuccessors()) {
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Label successor = labels.get(successorArc.getDestination().getId());
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arc_cost = Double.MAX_VALUE;
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if (!successor.isMarked() && data.isAllowed(successorArc)) {
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// This loop serves to get the length of the arc as
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// we know its origin and destination
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for (Arc arc : x.getNode().getSuccessors()) {
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if (successor.getNode().equals(arc.getDestination()) && data.getCost(arc) == data.getCost(successorArc)) {
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// data.getcost(arc) returns a cost considering the mode chosen:
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// TIME or LENGTH
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// Similar to using getLength / getMinimumTravelTime
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arc_cost = Math.min(data.getCost(arc), arc_cost);
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}
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}
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final double possible_path_cost = x.getCost() + arc_cost;
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if (successor.getCost() > possible_path_cost) {
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// Mise à jour du label
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successor.setPathCost(possible_path_cost);
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successor.setParentArc(successorArc);
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// Si le noeud n'a pas déjà été rajouté au tas, on le rajoute
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// isReached permet de vérifier en complexité O(1)
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// C'est un léger coût en mémoire pour un gain en vitesse
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if (successor.isReached()) {
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// removing then inserting resorts the binary heap
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tas.remove(successor);
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} else {
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successor.markReached();
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notifyNodeReached(successor.getNode());
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}
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tas.insert(successor);
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}
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}
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}
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}
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if (labels.get(data.getDestination().getId()).getParentArc() == null) {
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this.pathCost = 0;
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solution = new ShortestPathSolution(data, Status.INFEASIBLE);
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}
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else {
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// Create the path ...
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ArrayList<Arc> arcs_path = new ArrayList<>();
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Arc arc = labels.get(data.getDestination().getId()).getParentArc();
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// We will find the path using the parent nodes, from the destination to the
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// origin
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while (arc != null && arc.getDestination().getId() != data.getOrigin().getId()) {
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arcs_path.add(arc);
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arc = labels.get(arc.getOrigin().getId()).getParentArc();
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}
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notifyDestinationReached(data.getDestination());
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// Reverse the path...
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Collections.reverse(arcs_path);
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// Create the final solution.
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solution = new ShortestPathSolution(data, Status.OPTIMAL, new Path(graph, arcs_path));
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this.pathCost = labels.get(data.getDestination().getId()).getCost();
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}
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return solution;
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}
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@Override
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public ShortestPathData getInputData() {
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return (ShortestPathData) super.getInputData();
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}
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/**
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* Notify all observers that the origin has been processed.
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*
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* @param node Origin.
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*/
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public void notifyOriginProcessed(Node node) {
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for (ShortestPathObserver obs: getObservers()) {
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obs.notifyOriginProcessed(node);
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}
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}
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/**
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* Notify all observers that a node has been reached for the first time.
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*
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* @param node Node that has been reached.
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*/
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public void notifyNodeReached(Node node) {
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for (ShortestPathObserver obs: getObservers()) {
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obs.notifyNodeReached(node);
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}
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}
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/**
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* Notify all observers that a node has been marked, i.e. its final value has
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* been set.
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*
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* @param node Node that has been marked.
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*/
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public void notifyNodeMarked(Node node) {
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for (ShortestPathObserver obs: getObservers()) {
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obs.notifyNodeMarked(node);
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}
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}
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/**
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* Notify all observers that the destination has been reached.
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*
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* @param node Destination.
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*/
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public void notifyDestinationReached(Node node) {
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for (ShortestPathObserver obs: getObservers()) {
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obs.notifyDestinationReached(node);
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}
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}
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public double getCostPath() {
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return this.pathCost;
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}
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}
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