COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/elevator.h @ 2352:5e273e0bd5e2

Last change on this file since 2352:5e273e0bd5e2 was 2352:5e273e0bd5e2, checked in by Alpar Juttner, 13 years ago

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1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_ELEVATOR_H
20#define LEMON_ELEVATOR_H
21
22///\ingroup auxdat
23///\file
24///\brief Elevator class
25///
26///Elevator class implements an efficient data structure
27///for labeling items in push-relabel type algorithms.
28///
29
30#include <test/test_tools.h>
31namespace lemon {
32
33  ///Class for handling "labels" in push-relabel type algorithms.
34 
35  ///A class for handling "labels" in push-relabel type algorithms.
36  ///
37  ///\ingroup auxdat
38  ///Using this class you can assign "labels" (nonnegative integer numbers)
39  ///to the edges or nodes of a graph, manipulate and query them through
40  ///operations typically arising in "push-relabel" type algorithms.
41  ///
42  ///Each item is either \em active or not, and you can also choose a
43  ///highest level active item.
44  ///
45  ///\param Graph the underlying graph type
46  ///\param Item Type of the items the data is assigned to (Graph::Node,
47  ///Graph::Edge, Graph::UEdge)
48  template<class Graph, class Item>
49  class Elevator
50  {
51  public:
52    typedef typename std::vector<Item>::iterator Vit;
53    typedef DefaultMap<Graph,Item,Vit> VitMap;
54    typedef DefaultMap<Graph,Item,int> IntMap;
55
56    const Graph &_g;
57    int _max_level;
58    int _item_num;
59    VitMap _where;
60    IntMap _level;
61    std::vector<Item> _items;
62    std::vector<Vit> _first;
63    std::vector<Vit> _last_active;
64
65    int _highest_active;
66
67    void copy(Item i, Vit p)
68    {
69      _where[*p=i]=p;
70    }
71    void copy(Vit s, Vit p)
72    {
73      if(s!=p)
74        {
75          Item i=*s;
76          *p=i;
77          _where[i]=p;
78        }
79    }
80    void swap(Vit i, Vit j)
81    {
82      Item ti=*i;
83      Vit ct = _where[ti];
84      _where[ti]=_where[*i=*j];
85      _where[*j]=ct;
86      *j=ti;
87    }
88   
89    void checkDs() const
90    {
91      for(typename ItemSetTraits<Graph,Item>::ItemIt i(_g);i!=INVALID;++i)
92        {
93          Vit w=_where[i];
94          int l=_level[i];
95          check(*w==i,"GEBASZ: CORRUPT DS");
96          check(_first[l]<=w,"GEBASZ: CORRUPT DS");
97          check(_first[l+1]>w,"GEBASZ: CORRUPT DS");
98        }
99      for(int l=0;l<=_max_level;++l)
100        {
101          check(_first[l]<=_last_active[l]+1,"GEBASZ: CORRUPT DS");
102          check(_last_active[l]<_first[l+1],"GEBASZ: CORRUPT DS");
103          check(_first[l]<=_first[l+1],"GEBASZ: CORRUPT DS");
104        }
105      check(_highest_active<0 ||
106            _first[_highest_active]<=_last_active[_highest_active],
107            "GEBASZ: CORRUPT DS");
108    }
109
110  public:
111    ///Constructor with given maximum level.
112
113    ///Constructor with given maximum level.
114    ///
115    ///\param g The underlying graph
116    ///\param max_level Set the range of the possible labels to
117    ///[0...\c max_level]
118    Elevator(const Graph &g,int max_level) :
119      _g(g),
120      _max_level(max_level),
121      _item_num(_max_level),
122      _where(g),
123      _level(g,0),
124      _items(_max_level),
125      _first(_max_level+2),
126      _last_active(_max_level+2),
127      _highest_active(-1) {}
128    ///Constructor.
129
130    ///Constructor.
131    ///
132    ///\param g The underlying graph
133    ///The range of the possible labels is [0...\c max_level],
134    ///where \c max_level is equal to the number of labeled items in the graph.
135    Elevator(const Graph &g) :
136      _g(g),
137      _max_level(countItems<Graph, Item>(g)),
138      _item_num(_max_level),
139      _where(g),
140      _level(g,0),
141      _items(_max_level),
142      _first(_max_level+2),
143      _last_active(_max_level+2),
144      _highest_active(-1)
145    {
146    }
147 
148    ///Activate item \c i.
149    void activate(Item i)
150    {
151      const int l=_level[i];
152      swap(_where[i],++_last_active[l]);
153      if(l>_highest_active) _highest_active=l;
154    }
155 
156    ///Deactivate item \c i.
157    void deactivate(Item i) 
158    {
159      swap(_where[i],_last_active[_level[i]]--);
160      while(_highest_active>=0 &&
161            _last_active[_highest_active]<_first[_highest_active])
162        _highest_active--;
163    }
164
165    ///Query whether item \c i is active
166    bool active(Item i) const { return _where[i]<=_last_active[_level[i]]; }
167   
168    ///Return the level of item \c i.
169    int operator[](Item i) const { return _level[i]; }
170
171    ///Returns an active item on level \c l.
172
173    ///Returns an active item on level \c l.
174    ///
175    ///Returns an active item on level \c l or \ref INVALID if there is no such
176    ///an item. (\c l must be from the range [0...\c max_level].
177    Item operator[](int l) const
178    {
179      return _last_active[l]>=_first[l]?*_last_active[l]:INVALID;
180    }
181
182    ///Return the number of items on level \c l.
183    int onLevel(int l) const
184    {
185      return _first[l+1]-_first[l];
186    }
187    ///Return the number of items above level \c l.
188    int aboveLevel(int l) const
189    {
190      return _first[_max_level+1]-_first[l+1];
191    }
192    ///Return the number of active items on level \c l.
193    int activesOnLevel(int l) const
194    {
195      return _last_active[l]-_first[l]+1;
196    }
197    ///Return the maximum allowed level.
198    int maxLevel() const
199    {
200      return _max_level;
201    }   
202
203    ///\name Highest Active Item
204    ///Functions for working with the highest level
205    ///active item.
206
207    ///@{
208
209    ///Return a highest level active item.
210 
211    ///Return a highest level active item.
212    ///
213    ///\return the highest level active item or INVALID if there is no active
214    ///item.
215    Item highestActive() const
216    {
217      return _highest_active>=0?*_last_active[_highest_active]:INVALID;
218    }
219
220    ///Return a highest active level.
221
222    ///Return a highest active level.
223    ///
224    ///\return the level of the highest active item or -1 if there is no active
225    ///item.
226    int highestActiveLevel() const
227    {
228      return _highest_active;
229    }
230
231    ///Lift the highest active item by one.
232
233    ///Lift the item returned by highestActive() by one.
234    ///
235    void liftHighestActive()
236    {
237      ++_level[*_last_active[_highest_active]];
238      swap(_last_active[_highest_active]--,_last_active[_highest_active+1]);
239      --_first[++_highest_active];
240    }
241
242    ///Lift the highest active item.
243
244    ///Lift the item returned by highestActive() to level \c new_level.
245    ///
246    ///\warning \c new_level must be strictly higher
247    ///than the current level.
248    ///
249    void liftHighestActiveTo(int new_level)
250    {
251      const Item li = *_last_active[_highest_active];
252     
253      copy(--_first[_highest_active+1],_last_active[_highest_active]--);
254      for(int l=_highest_active+1;l<new_level;l++)
255        {
256          copy(--_first[l+1],_first[l]);
257          --_last_active[l];
258        }
259      copy(li,_first[new_level]);
260      _level[li]=new_level;
261      _highest_active=new_level;
262    }
263   
264    ///@}
265   
266    ///Lift an active item to a higher level.
267
268    ///Lift an active item to a higher level.
269    ///\param i The item to be lifted. It must be active.
270    ///\param new_level The new level of \c i. It must be strictly higher
271    ///than the current level.
272    ///
273    void liftTo(Item i, int new_level)
274    {
275      const int lo = _level[i];
276      const Vit w = _where[i];
277
278      copy(_last_active[lo],w);
279      copy(--_first[lo+1],_last_active[lo]--);
280      for(int l=lo+1;l<new_level;l++)
281        {
282          copy(_last_active[l],_first[l]);
283          copy(--_first[l+1],_last_active[l]--);
284        }
285      copy(i,_first[new_level]);
286      _level[i]=new_level;
287      if(new_level>_highest_active) _highest_active=new_level;
288    }
289
290//     void liftToTop(int l)
291//     {
292//       const Vit f=_first[l];
293//       for(int i=l;i<=_max_level;i++)
294//      {
295//        _first[i]=f;
296//        _last_active[i]=f-1;
297//      }
298//       for(Vit i=f;i!=_items.end();++i)
299//      _level[*i]=_max_level;
300//       for(_highest_active=l-1;
301//        _highest_active>=0 &&
302//          _last_active[_highest_active]<_first[_highest_active];
303//        _highest_active--) ;
304//     }
305   
306    ///Lift all nodes on and above a level to the top (and deactivate them).
307
308    ///This function lifts all nodes on and above level \c l to \c maxLevel(),
309    ///and
310    ///also deactivates them.
311    void liftToTop(int l)
312    {
313      const Vit f=_first[l];
314      const Vit tl=_first[_max_level];
315      for(Vit i=f;i!=tl;++i)
316        _level[*i]=_max_level;
317      for(int i=l;i<=_max_level;i++)
318        {
319          _first[i]=f;
320          _last_active[i]=f-1;
321        }
322      for(_highest_active=l-1;
323          _highest_active>=0 &&
324            _last_active[_highest_active]<_first[_highest_active];
325          _highest_active--) ;
326    }
327   
328  private:
329    int _init_lev;
330    Vit _init_num;
331
332  public:
333
334    ///\name Initialization
335    ///Using this function you can initialize the levels of the item.
336    ///\n
337    ///This initializatios is started with calling \c initStart().
338    ///Then the
339    ///items should be listed levels by levels statring with the lowest one
340    ///(with level 0). This is done by using \c initAddItem()
341    ///and \c initNewLevel(). Finally \c initFinish() must be called.
342    ///The items not listed will be put on the highest level.
343    ///@{
344
345    ///Start the initialization process.
346
347    void initStart()
348    {
349      _init_lev=0;
350      _init_num=_items.begin();
351      _first[0]=_items.begin();
352      _last_active[0]=_items.begin()-1;
353      Vit n=_items.begin();
354      for(typename ItemSetTraits<Graph,Item>::ItemIt i(_g);i!=INVALID;++i)
355        {
356          *n=i;
357          _where[i]=n;
358          _level[i]=_max_level;
359          ++n;
360        }
361    }
362
363    ///Add an item to the current level.
364
365    void initAddItem(Item i)
366    {
367     swap(_where[i],_init_num);
368      _level[i]=_init_lev;
369      ++_init_num;
370    }
371
372    ///Start a new level.
373
374    ///Start a new level.
375    ///It shouldn't be used before the items on level 0 are listed.
376    void initNewLevel()
377    {
378      _init_lev++;
379      _first[_init_lev]=_init_num;
380      _last_active[_init_lev]=_init_num-1;
381    }
382
383    ///Finalize the initialization process.
384
385    void initFinish()
386    {
387      for(_init_lev++;_init_lev<=_max_level;_init_lev++)
388        {
389          _first[_init_lev]=_init_num;
390          _last_active[_init_lev]=_init_num-1;
391        }
392      _first[_max_level+1]=_items.begin()+_item_num;
393      _last_active[_max_level+1]=_items.begin()+_item_num-1;
394    }
395
396    ///@}
397
398  };
399
400} //END OF NAMESPACE LEMON
401
402#endif
403
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