tpl_spanning_tree.H

/* Aleph-w

     / \  | | ___ _ __ | |__      __      __
    / _ \ | |/ _ \ '_ \| '_ \ ____\ \ /\ / / Data structures & Algorithms
   / ___ \| |  __/ |_) | | | |_____\ V  V /  version 1.9b
  /_/   \_\_|\___| .__/|_| |_|      \_/\_/   https://github.com/lrleon/Aleph-w
                 |_|         

  This file is part of Aleph-w library

  Copyright (c) 2002-2018 Leandro Rabindranath Leon & Alejandro Mujica

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
# ifndef TPL_SPANNING_TREE_H
# define TPL_SPANNING_TREE_H

# include <tpl_graph.H>

namespace Aleph {


    template <class GT, class SA = Dft_Show_Arc<GT> > 
class Find_Depth_First_Spanning_Tree
{
  SA   sa;
  GT * gptr = nullptr;
  GT * tptr = nullptr;

  bool build_tree(typename GT::Node * gnode, typename GT::Arc * garc, 
                  typename GT::Node * tnode)
  {
    NODE_BITS(gnode).set_bit(Spanning_Tree, true); // marcar nodo 
    ARC_BITS(garc).set_bit(Spanning_Tree, true);   // marcar arco

    auto tree_tgt_node = tptr->insert_node(gnode->get_info());
    GT::map_nodes(gnode, tree_tgt_node);

    auto tarc = tptr->insert_arc(tnode, tree_tgt_node, garc->get_info()); 
    GT::map_arcs(garc, tarc);

    tnode = tree_tgt_node; 
    if (tptr->get_num_nodes() == gptr->get_num_nodes()) // ¿grafo abarcado?
      return true; // tree ya contiene el árbol abarcador

    assert(tptr->get_num_nodes() > tptr->get_num_arcs()); // debe ser acíclico

    for (Node_Arc_Iterator<GT, SA> i(gnode, sa); 
         i.has_curr() and tptr->get_num_nodes() < gptr->get_num_nodes();
         i.next_ne())
      {
        auto arc = i.get_current_arc_ne();
        if (IS_ARC_VISITED(arc, Spanning_Tree)) 
          continue;

        auto arc_tgt_node = i.get_tgt_node();
        if (IS_NODE_VISITED(arc_tgt_node, Spanning_Tree))
          continue; // destino ya visitado desde otro arco

        if (build_tree(arc_tgt_node, arc, tnode))
          return false;
      }

    return false;
  }

  bool build_tree(GT & g, typename GT::Node * gnode, GT & tree)
  {
    gptr = &g;
    tptr = &tree;

    gptr->reset_nodes();
    gptr->reset_arcs(); 

    clear_graph(*tptr); // asegurar que árbol destino esté vacío
  
    NODE_BITS(gnode).set_bit(Spanning_Tree, true); // marcar gnode
  
    auto tnode = tree.insert_node(gnode->get_info()); 
    GT::map_nodes(gnode, tnode);
  
    for (Node_Arc_Iterator<GT, SA> i(gnode, sa); 
         i.has_curr() and tptr->get_num_nodes() < gptr->get_num_nodes(); 
         i.next_ne())
      {
        auto arc = i.get_current_arc_ne();
        if (IS_ARC_VISITED(arc, Spanning_Tree)) 
          continue;

        auto arc_tgt_node = i.get_tgt_node();
        if (IS_NODE_VISITED(arc_tgt_node, Spanning_Tree))
          continue; // destino ya visitado desde otro arco

        if (build_tree(arc_tgt_node, arc, tnode))
          return false;
      }

    return true;
  }

public:

  Find_Depth_First_Spanning_Tree(SA __sa = SA()) : sa(__sa) { /* empty */ }

  typename GT::Node * operator () (GT & g, GT & tree)
  {
    auto start = g.get_first_node();
    if (not build_tree(g, start, tree)) 
      return nullptr;

    return start;
  }

  typename GT::Node * operator () (GT & g, typename GT::Node * gnode, GT & tree)
  {
    this->build_tree(g, gnode, tree);
    return (typename GT::Node *) NODE_COOKIE(gnode);
  }
};



      template <class GT, class SA = Dft_Show_Arc<GT> > 
class Find_Breadth_First_Spanning_Tree
{
  SA & sa;

  void build_tree(GT & g, typename GT::Node * gp, GT & tree)
  {
    g.reset_bit_nodes(Spanning_Tree);
    g.reset_bit_arcs(Spanning_Tree);

    clear_graph(tree); 

    unique_ptr<typename GT::Node> tp_auto(new typename GT::Node(gp));
    tree.insert_node(tp_auto.get());
    GT::map_nodes(gp, tp_auto.release());

    DynListQueue<typename GT::Arc*> q; // insertar en cola arcos gp
    for (Node_Arc_Iterator<GT, SA> i(gp, sa); i.has_curr(); i.next_ne())
      q.put(i.get_current_arc_ne());

    NODE_BITS(gp).set_bit(Spanning_Tree, true); 

    while (not q.is_empty()) 
      {
        auto garc = q.get(); 
        ARC_BITS(garc).set_bit(Spanning_Tree, true); 
        auto gsrc = g.get_src_node(garc);  
        auto gtgt = g.get_tgt_node(garc);

        if (IS_NODE_VISITED(gsrc, Spanning_Tree) and 
            IS_NODE_VISITED(gtgt, Spanning_Tree))
          continue; // los dos nodos de garc ya fueron visitados

        if (IS_NODE_VISITED(gtgt, Spanning_Tree)) // ¿gtgt visitado?
          std::swap(gsrc, gtgt); // sí, intercámbielo con gsrc

        auto tsrc = mapped_node<GT>(gsrc);
        NODE_BITS(gtgt).set_bit(Spanning_Tree, true); // gtgt visitado

            // crear copia de gtgt, insertarlo en tree y mapearlo
        unique_ptr<typename GT::Node> ttgt_auto(new typename GT::Node(gtgt));
        tree.insert_node(ttgt_auto.get());
        auto ttgt = ttgt_auto.release();
        GT::map_nodes(gtgt, ttgt);

            // insertar nuevo arco en tree y mapearlo
        auto tarc = tree.insert_arc(tsrc, ttgt, garc->get_info());
        GT::map_arcs(garc, tarc);
        if (tree.get_num_nodes() == g.get_num_nodes()) // ¿abarca a g?
          break; 

            // insertar en cola arcos de gtgt
        for (Node_Arc_Iterator<GT, SA> i(gtgt, sa); i.has_curr(); i.next_ne())
          {
            auto current_arc = i.get_current_arc_ne();
            if (IS_ARC_VISITED(current_arc, Spanning_Tree)) 
              continue;

                // revise nodos de arcos para ver si han sido visitados
            if (IS_NODE_VISITED(g.get_src_node(current_arc), Spanning_Tree) and 
                IS_NODE_VISITED(g.get_tgt_node(current_arc), Spanning_Tree))
              continue; // nodos ya visitados ==> no meter arco
            q.put(current_arc);
          }
      }
  }

public:

  Find_Breadth_First_Spanning_Tree(SA && __sa = SA()) : sa(__sa) { /* empty */ }

  Find_Breadth_First_Spanning_Tree(SA & __sa) : sa(__sa) { /* empty */ }

    void operator () (GT & g, typename GT::Node * gnode, GT & tree) 
    {
      find_breadth_first_spanning_tree <GT, SA> (g, gnode, tree);
    }
  };


      template <class GT>
class Build_Spanning_Tree
{
public:

  GT operator () (const DynArray<typename GT::Arc> *  arcs) const
  {
    return build_spanning_tree(arcs);
  }
};


} // end namespace Aleph

# endif //  TPL_SPANNING_TREE_H