edge_xover.cpp

// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-

// "edge_xover.cpp"

// (c) OPAC Team, LIFL, 2003

/* This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library 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
   Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   
   Contact: cahon@lifl.fr
*/

#include <assert.h>
#include <values.h>

#include <utils/eoRNG.h>

#include "edge_xover.h"

void EdgeXover :: build_map (const Route & __par1, const Route & __par2) {
  
  unsigned len = __par1.size () ;
  
  /* Initialization */
  _map.clear () ;
  _map.resize (len) ;
  
  for (unsigned i = 0 ; i < len ; i ++) {
    _map [__par1 [i]].insert (__par1 [(i + 1) % len]) ;
    _map [__par2 [i]].insert (__par2 [(i + 1) % len]) ;
    _map [__par1 [i]].insert (__par1 [(i - 1 + len) % len]) ;
    _map [__par2 [i]].insert (__par2 [(i - 1 + len) % len]) ;
  }
  
  visited.clear () ;
  visited.resize (len, false) ;
}

void EdgeXover :: remove_entry (unsigned __vertex, std :: vector <std :: set <unsigned> > & __map) {
  
  std :: set <unsigned> & neigh = __map [__vertex] ;

  for (std :: set <unsigned> :: iterator it = neigh.begin () ;
       it != neigh.end () ;
       it ++)
    __map [* it].erase (__vertex) ; 
      
}

void EdgeXover :: add_vertex (unsigned __vertex, Route & __child) {
  
  visited [__vertex] = true ;
  __child.push_back (__vertex) ;    
  remove_entry (__vertex, _map) ; /* Removing entries */    
}

void EdgeXover :: cross (const Route & __par1, const Route & __par2, Route & __child) {
  
  build_map (__par1, __par2) ;
  
  unsigned len = __par1.size () ;
 
  /* Go ! */
  __child.clear () ;
  
  unsigned cur_vertex = rng.random (len) ;
  
  add_vertex (cur_vertex, __child) ;

  for (unsigned i = 1 ; i < len ; i ++) {
    
    unsigned len_min_entry = MAXINT ;
    
    std :: set <unsigned> & neigh = _map [cur_vertex] ;
    
    for (std :: set <unsigned> :: iterator it = neigh.begin () ;
         it != neigh.end () ;
         it ++) {      
      unsigned l = _map [* it].size () ;
      if (len_min_entry > l)
        len_min_entry = l ;
    }
    
    std :: vector <unsigned> cand ; /* Candidates */
    
    for (std :: set <unsigned> :: iterator it = neigh.begin () ;
         it != neigh.end () ;
         it ++) {      
      unsigned l = _map [* it].size () ;
      if (len_min_entry == l)
        cand.push_back (* it) ;
    }
       
    if (! cand.size ()) {
      
      /* Oh no ! Implicit mutation */      
      for (unsigned j = 0 ; j < len ; j ++)
        if (! visited [j])
          cand.push_back (j) ;
    }

    cur_vertex = cand [rng.random (cand.size ())] ;
    
    add_vertex (cur_vertex, __child) ;
  } 
}

bool EdgeXover :: operator () (Route & __route1, Route & __route2) {
  
  // Init. copy
  Route par [2] ;
  par [0] = __route1 ;
  par [1] = __route2 ;
  
  cross (par [0], par [1], __route1) ;
  cross (par [1], par [0], __route2) ;
  
  __route1.invalidate () ;
  __route2.invalidate () ;

  return true ;
}

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