Update.

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentGraphicObserver.java

@@ -0,0 +1,46 @@
+package org.insa.algo.weakconnectivity;
+
+import java.awt.Color;
+import java.util.ArrayList;
+
+import org.insa.drawing.Drawing;
+import org.insa.drawing.graph.GraphDrawing;
+import org.insa.graph.Node;
+
+public class WeaklyConnectedComponentGraphicObserver extends WeaklyConnectedComponentObserver {
+	
+	private static final Color[] COLORS = {
+		Color.BLUE, Color.ORANGE, Color.GREEN, Color.YELLOW, Color.RED
+	};
+
+	// Drawing + Graph drawing
+	private Drawing drawing;
+	private GraphDrawing gdrawing;
+	
+	// Current index color
+	private int cindex = 0;
+	
+	public WeaklyConnectedComponentGraphicObserver(Drawing drawing) {
+		super(true);
+		this.drawing = drawing;
+		this.gdrawing = new GraphDrawing(drawing);
+		this.drawing.setAutoRepaint(true);
+	}
+
+	@Override
+	public void notifyStartComponent(Node curNode) {
+		this.drawing.setColor(COLORS[cindex]);
+		cindex = (cindex + 1) % COLORS.length;
+	}
+
+	@Override
+	public void notifyNewNodeInComponent(Node node) {
+		this.gdrawing.drawPoint(node.getPoint(), 5);
+		this.drawing.repaint();
+	}
+
+	@Override
+	public void notifyEndComponent(ArrayList<Node> nodes) {
+	}
+
+}

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentObserver.java

@@ -0,0 +1,38 @@
+package org.insa.algo.weakconnectivity;
+
+import java.util.ArrayList;
+
+import org.insa.algo.AbstractObserver;
+import org.insa.graph.Node;
+
+public abstract class WeaklyConnectedComponentObserver extends AbstractObserver {
+
+	/**
+	 * {@inheritDoc}
+	 */
+	protected WeaklyConnectedComponentObserver(boolean isGraphic) {
+		super(isGraphic);
+	}
+	
+	/**
+	 * Notify that the algorithm is entering a new component.
+	 * 
+	 * @param curNode Starting node for the component.
+	 */
+	public abstract void notifyStartComponent(Node curNode);
+	
+	/**
+	 * Notify that a new node has been found for the current component.
+	 * 
+	 * @param node New node found for the current component.
+	 */
+	public abstract void notifyNewNodeInComponent(Node node);
+	
+	/**
+	 * Notify that the algorithm has computed a new component.
+	 * 
+	 * @param nodes List of nodes in the component.
+	 */
+	public abstract void notifyEndComponent(ArrayList<Node> nodes);
+
+}

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentTextObserver.java

@@ -0,0 +1,37 @@
+package org.insa.algo.weakconnectivity;
+
+import java.io.PrintStream;
+import java.util.ArrayList;
+
+import org.insa.graph.Node;
+
+public class WeaklyConnectedComponentTextObserver extends WeaklyConnectedComponentObserver {
+	
+	// Number of the current component.
+	private int numComponent = 1;
+	
+	// Output stream
+	PrintStream stream;
+
+	public WeaklyConnectedComponentTextObserver(PrintStream stream) {
+		super(false);
+		this.stream = stream;
+	}
+
+	@Override
+	public void notifyStartComponent(Node curNode) {
+		stream.print("Entering component #" + numComponent + " from node #" + curNode.getId() + "... ");
+	}
+
+	@Override
+	public void notifyNewNodeInComponent(Node node) {
+	}
+
+	@Override
+	public void notifyEndComponent(ArrayList<Node> nodes) {
+		stream.println(nodes.size() + " nodes found.");
+		stream.flush();
+		numComponent += 1;
+	}
+
+}

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsAlgorithm.java

@@ -0,0 +1,127 @@
+package org.insa.algo.weakconnectivity;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.HashSet;
+
+import org.insa.algo.AbstractAlgorithm;
+import org.insa.algo.AbstractObserver;
+import org.insa.algo.AbstractSolution;
+import org.insa.algo.AbstractSolution.Status;
+import org.insa.graph.Arc;
+import org.insa.graph.Graph;
+import org.insa.graph.Node;
+
+public class WeaklyConnectedComponentsAlgorithm extends AbstractAlgorithm {
+
+	/**
+	 * 
+	 * @param instance
+	 * @param logOutput
+	 */
+	public WeaklyConnectedComponentsAlgorithm(WeaklyConnectedComponentsInstance instance) {
+		super(instance);
+	}
+	
+	/**
+	 * @return An adjacency list for the undirected graph equivalent to the stored graph.
+	 */
+	protected ArrayList<HashSet<Integer>> createUndirectedGraph() {
+		int nNodes = getInstance().getGraph().getNodes().size();
+		ArrayList<HashSet<Integer>> res = new ArrayList<HashSet<Integer>>(nNodes);
+		for (int i = 0; i < nNodes; ++i) {
+			res.add(new HashSet<Integer>());
+		}		
+		
+		for (Node node: getInstance().getGraph().getNodes()) {
+			for (Arc arc: node.getSuccessors()) {
+				res.get(node.getId()).add(arc.getDestination().getId());
+				if (arc.getInfo().isOneWay()) {
+					res.get(arc.getDestination().getId()).add(node.getId());
+				}
+			}
+		}
+		
+		return res;
+	}
+	
+	/**
+	 * Apply a breadth first search algorithm on the given undirected graph (adjacency list),
+	 * starting at node cur, and marking nodes in marked.
+	 * 
+	 * @param marked
+	 * @param cur
+	 * 
+	 * @return
+	 */
+	protected ArrayList<Node> bfs(ArrayList<HashSet<Integer>> ugraph, boolean[] marked, int cur) {
+		ArrayList<Node> nodes = getInstance().getGraph().getNodes();
+		ArrayList<Node> component = new ArrayList<Node>();
+		
+		// Using a queue because we are doing a BFS
+		Queue<Integer> queue = new LinkedList<Integer>();
+
+		for (AbstractObserver obs: getObservers()) {
+			((WeaklyConnectedComponentObserver)obs).notifyStartComponent(nodes.get(cur));
+		}
+		
+		// Add original node and loop until the queue is empty.
+		queue.add(cur);
+		marked[cur] = true;
+		while (!queue.isEmpty()) {
+			Node node = nodes.get(queue.remove());
+			component.add(node);
+			
+			// notify observers
+			for (AbstractObserver obs: getObservers()) ((WeaklyConnectedComponentObserver)obs).notifyNewNodeInComponent(node);
+			
+			for (Integer destId: ugraph.get(node.getId())) {
+				Node dest = nodes.get(destId);
+				if (!marked[dest.getId()]) {
+					queue.add(destId);
+					marked[destId] = true;
+				}
+			}
+		}
+		
+		for (AbstractObserver obs: getObservers()) {
+			((WeaklyConnectedComponentObserver)obs).notifyEndComponent(component);
+		}
+		
+		return component;
+	}
+
+	@Override
+	protected AbstractSolution doRun() {
+		
+		Instant start = Instant.now();
+
+		Graph graph = getInstance().getGraph();
+		ArrayList<HashSet<Integer>> ugraph = createUndirectedGraph();
+		boolean[] marked = new boolean[graph.getNodes().size()];
+		Arrays.fill(marked, false);
+		
+		ArrayList<ArrayList<Node>> components = new ArrayList<ArrayList<Node>>();
+		
+		// perform algorithm
+		int cur = 0;
+		while (cur < marked.length) {
+			// Apply BFS
+			components.add(this.bfs(ugraph, marked, cur));
+			
+			// Find next non-marked
+			for (; cur < marked.length && marked[cur]; ++cur);
+		}
+		
+		Duration solvingTime = Duration.between(start, Instant.now());
+		
+		return new WeaklyConnectedComponentsSolution((WeaklyConnectedComponentsInstance)getInstance(), 
+				solvingTime, Status.OPTIMAL, components);
+	}
+
+}

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsInstance.java

@@ -0,0 +1,16 @@
+package org.insa.algo.weakconnectivity;
+
+import org.insa.algo.AbstractInstance;
+import org.insa.graph.Graph;
+
+public class WeaklyConnectedComponentsInstance extends AbstractInstance {
+
+	/**
+	 * 
+	 * @param graph
+	 */
+	public WeaklyConnectedComponentsInstance(Graph graph) {
+		super(graph);
+	}
+	
+}

src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsSolution.java

@@ -0,0 +1,29 @@
+package org.insa.algo.weakconnectivity;
+
+import java.time.Duration;
+import java.util.ArrayList;
+
+import org.insa.algo.AbstractSolution;
+import org.insa.graph.Node;
+
+public class WeaklyConnectedComponentsSolution extends AbstractSolution {
+	
+	// Components
+	private ArrayList<ArrayList<Node>> components;
+
+	protected WeaklyConnectedComponentsSolution(WeaklyConnectedComponentsInstance instance) {
+		super(instance);
+	}
+	
+	protected WeaklyConnectedComponentsSolution(WeaklyConnectedComponentsInstance instance, 
+					   Duration solvingTime, Status status, ArrayList<ArrayList<Node>> components) {
+		super(instance, solvingTime, status);
+		this.components = components;
+	}
+	
+	/**
+	 * @return Components of the solution, if any.
+	 */
+	public ArrayList<ArrayList<Node>> getComponents() { return components; }
+
+}