127 行
3.5 KiB
Java
127 行
3.5 KiB
Java
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);
|
|
}
|
|
|
|
}
|