VTK/Examples/Cxx/Graphs/BreadthFirstSearchIterator

#include <vtkSmartPointer.h>
#include <vtkMutableDirectedGraph.h>
#include <vtkTree.h>
#include <vtkTreeBFSIterator.h>
 
int main(int argc, char *argv[])
{
  //create a tree
  vtkSmartPointer<vtkMutableDirectedGraph> g = 
    vtkSmartPointer<vtkMutableDirectedGraph>::New();
 
  vtkIdType v1 = g->AddVertex();
  vtkIdType v2 = g->AddVertex();
  vtkIdType v3 = g->AddVertex();
 
  g->AddEdge(v1, v2);
  g->AddEdge(v1, v3);
 
  vtkSmartPointer<vtkTree> tree =
    vtkSmartPointer<vtkTree>::New();
  tree->CheckedShallowCopy(g);
 
  //setup the iterator
  vtkIdType root = 0;
 
  vtkSmartPointer<vtkTreeBFSIterator> bfsIterator = 
      vtkSmartPointer<vtkTreeBFSIterator>::New();
  bfsIterator->SetStartVertex(root);
  bfsIterator->SetTree(tree);
 
  //traverse the tree in a breadth first fashion
  while(bfsIterator->HasNext())
    {
    vtkIdType nextVertex = bfsIterator->Next();
    std::cout << "Next vertex: " << nextVertex << std::endl;
    }
 
  return EXIT_SUCCESS;
}