From 4bd0c74fa45751fd1d0432732d6df83b82c93acf Mon Sep 17 00:00:00 2001
From: Clement LACAU <lacau@insa-toulouse.fr>
Date: Fri, 5 Apr 2024 12:38:13 +0200
Subject: [PATCH] dijkstra, not functional

---
 .../shortestpath/DijkstraAlgorithm.java       | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/shortestpath/DijkstraAlgorithm.java b/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/shortestpath/DijkstraAlgorithm.java
index bacb8e3..c89baa9 100644
--- a/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/shortestpath/DijkstraAlgorithm.java
+++ b/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/shortestpath/DijkstraAlgorithm.java
@@ -1,5 +1,13 @@
 package org.insa.graphs.algorithm.shortestpath;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.insa.graphs.algorithm.utils.BinaryHeap;
+import org.insa.graphs.model.Arc;
+import org.insa.graphs.model.Graph;
+import org.insa.graphs.model.Node;
+
 public class DijkstraAlgorithm extends ShortestPathAlgorithm {
 
     public DijkstraAlgorithm(ShortestPathData data) {
@@ -11,6 +19,58 @@ public class DijkstraAlgorithm extends ShortestPathAlgorithm {
         final ShortestPathData data = getInputData();
         ShortestPathSolution solution = null;
         // TODO:
+
+        // Heap of "sommets"
+        BinaryHeap<Label> queue = new BinaryHeap<Label>(); // change to a comparable type
+
+        Graph graph = data.getGraph();
+        final int nbNodes = graph.size();
+
+        // Initialize array of distances.
+        double[] distances = new double[nbNodes];
+        Arrays.fill(distances, Double.POSITIVE_INFINITY);
+        distances[data.getOrigin().getId()] = 0;
+
+        // Notify observers about the first event (origin processed).
+        notifyOriginProcessed(data.getOrigin());
+
+        // Init Dijkstra
+        ArrayList<Label> labels = new ArrayList<Label>();
+        for (Node node : graph.getNodes()) {
+            labels.add(new Label(node));
+        }
+        // Nodes set
+        for (Label label : labels) {
+            label.marked = false;
+            label.setPathCost(Float.MAX_VALUE);
+            label.parentNode = null;
+        }
+        // Origin set
+        Label s = labels.get(0);
+        s.setPathCost(0);
+        queue.insert(s);
+
+        boolean trouve = false; // TODO : breaking condition
+        Label x;
+        while (!queue.isEmpty() && !trouve) {
+            x = queue.ExtractMin(); 
+            x.mark();
+
+            for (Arc arc : x.node.getSuccessors()) {
+                // TODO : Retrieve label with node 
+                Label y;
+                if (!arc.getDestination().marked) {
+                    float new_cost = x.getCost() + (float) data.getCost(arc);
+                    if (y.getCost() > new_cost) {
+                    y.setPathCost(new_cost);
+                    queue.insert(y);
+                    y.setParentNode(x.getNode());
+                    }
+                }
+            }
+        }
+
+
         return solution;
     }