Ejemplo n.º 1
0
 /**
  * Dijkstra doesn't allow negative edge weights so throw an exception if one was found.
  *
  * @throws IllegalArgumentException if the graph contains negative weights
  */
 private void checkForNegativeWeights() {
   for (Edge e : graph.getEdges()) {
     if (e.getWeight() < 0) {
       throw new IllegalArgumentException("graph contains negative weights!");
     }
   }
 }
Ejemplo n.º 2
0
  private void executeDijkstra() {
    // determine minimum distance vertex and add it to the path.
    while (!this.priorityQueue.isEmpty()) {
      Vertex vertex = this.priorityQueue.extractMin();

      for (Edge e : graph.getIncidentEdgesOf(vertex)) {
        relax(vertex, e.getVertexB(), e.getWeight(), dist, pred);
      }
    }
  }
Ejemplo n.º 3
0
  /**
   * Set every distance to int.max and sets the start vertex by setting distance to 0
   *
   * @throws IllegalArgumentException if the graph contains negative weights
   * @param start
   */
  private void init(Vertex start) throws IllegalArgumentException {
    checkForNegativeWeights();

    for (Vertex v : graph.getVertices()) {
      dist.put(v, Double.MAX_VALUE);
    }

    // sets start Vertex by setting distance to 0
    dist.put(start, 0.0);
  }