tpl_test_path.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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*/
 
 
# ifndef TEST_PATH_H
# define TEST_PATH_H
 
# include <tpl_graph.H>
 
namespace Aleph {
 
 
      template <class GT, class SA = Dft_Show_Arc<GT> > 
class Test_For_Path
{
  SA sa;
  typename GT::Node * tgt = nullptr;
 
  bool test_path(typename GT::Node * curr)  
  {
    if (curr == tgt) 
      return true; // se alcanzó a tgt
 
    if (IS_NODE_VISITED(curr, Find_Path)) // ¿se visitó curr_node?
      return false; // sí, no explore
 
    NODE_BITS(curr).set_bit(Find_Path, true); // pintar curr_node
 
    // buscar recursivamente a través de arcos de curr 
    for (Node_Arc_Iterator<GT, SA> i(curr, sa); i.has_curr(); i.next_ne())
      { 
        typename GT::Arc * arc = i.get_current_arc_ne();
        if (IS_ARC_VISITED(arc, Find_Path)) 
          continue; 
 
        ARC_BITS(arc).set_bit(Find_Path, true); // pintar arco
        if (test_path(i.get_tgt_node())) 
          return true;
      }
 
    // todos los arcos adyacentes de curr_node explorados sin
    // encontrar a end_node ==> no existe camino por curr_node
    return false;
  }
 
  bool test_path(const GT & g, typename GT::Node * src, typename GT::Node * dest)
  {      // si el grafo es conexo ==> existe camino
    if (not g.is_digraph() and g.get_num_arcs() >= g.get_num_nodes()) 
      return true;
 
    g.reset_bit_nodes(Find_Path); 
    g.reset_bit_arcs(Find_Path);
 
    tgt = dest;
 
        // buscar recursivamente por arcos adyacentes a src
    for (Node_Arc_Iterator<GT, SA> i(src, sa); i.has_curr(); i.next_ne())
      {
        typename GT::Arc * arc = i.get_current_arc_ne();
        ARC_BITS(arc).set_bit(Find_Path, true); // marcar arco
        if (test_path(i.get_tgt_node())) 
          return true; 
      }
 
    // todos los arcos de start_node han sido explorados sin 
    // encontrar camino hasta end_node ==> no existe camino
    return false;
  }
 
public:
 
  Test_For_Path(SA __sa = SA()) : sa(__sa) { /* empty */ }
 
  bool operator () (const GT& g, typename GT::Node * start_node, 
        typename GT::Node * end_node) 
  {
    return test_path(g, start_node, end_node);
  }
};
 
 
 
} // end namespace Aleph
 
# endif // TEST_PAT_H