Example #1
0
  public static Map computeLevels(
      Map vertexLevelMap, DigraphIteration digraph, Object root, boolean longest) {
    if (vertexLevelMap == null) vertexLevelMap = new HashMap();

    MutableInteger rootLevel = (MutableInteger) vertexLevelMap.get(root);
    if (rootLevel == null) {
      rootLevel = new MutableInteger(0);
      vertexLevelMap.put(root, rootLevel);
    }

    for (ArcIterator i = digraph.outgoingIterator(root); i.hasNext(); ) {
      i.next();
      Object child = i.getDestination();
      int childLevelCandidate = rootLevel.intValue() + 1;
      MutableInteger childLevel = (MutableInteger) vertexLevelMap.get(child);
      if (childLevel == null) {
        childLevel = new MutableInteger(childLevelCandidate);
        vertexLevelMap.put(child, childLevel);
        computeLevels(vertexLevelMap, digraph, child, longest);
      } else if ((longest && childLevel.intValue() < childLevelCandidate)
          || (!longest && childLevel.intValue() > childLevelCandidate)) {
        childLevel.setValue(childLevelCandidate);
        computeLevels(vertexLevelMap, digraph, child, longest);
      }
    }

    return vertexLevelMap;
  }
Example #2
0
  public static List findCycles(DigraphIteration graph) {
    ArrayStack stack = new ArrayStack();
    ArrayStack path = new ArrayStack();
    Set seen = new HashSet();
    List cycles = new ArrayList();
    Iterator vertexIterator = graph.vertexIterator();

    while (vertexIterator.hasNext()) {
      while (vertexIterator.hasNext()) {
        Object vertex = vertexIterator.next();
        if (seen.add(vertex)) {
          stack.push(graph.outgoingIterator(vertex));
          path.push(vertex);
          break;
        }
      }

      while (!stack.isEmpty()) {
        ArcIterator i = (ArcIterator) stack.peek();
        Object origin = i.getOrigin();
        boolean subtreeIsTraversed = true;
        while (i.hasNext()) {
          i.next();
          Object dst = i.getDestination();
          int index = path.indexOf(dst);
          if (index < 0) {
            seen.add(dst);
            stack.push(graph.outgoingIterator(dst));
            path.push(dst);
            subtreeIsTraversed = false;
            break;
          } else {
            cycles.add(new ArrayList(path.subList(index, path.size())));
          }
        }
        if (subtreeIsTraversed) {
          stack.pop();
          path.pop();
        }
      }
    }
    return cycles;
  }
Example #3
0
  public static Map shiftLevelsDown(Map vertexLevelMap, DigraphIteration digraph, Object root) {
    int minChildLevel = Integer.MAX_VALUE;
    for (ArcIterator i = digraph.outgoingIterator(root); i.hasNext(); ) {
      i.next();
      Object child = i.getDestination();
      shiftLevelsDown(vertexLevelMap, digraph, child);
      MutableInteger childLevel = (MutableInteger) vertexLevelMap.get(child);
      minChildLevel =
          (minChildLevel <= childLevel.intValue() ? minChildLevel : childLevel.intValue());
    }

    if (minChildLevel != Integer.MAX_VALUE) {
      MutableInteger rootLevel = (MutableInteger) vertexLevelMap.get(root);
      rootLevel.setValue(minChildLevel - 1);
    }

    return vertexLevelMap;
  }