COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/jacint/max_flow_no_stack.h @ 715:665689d86225

Last change on this file since 715:665689d86225 was 714:104069336039, checked in by jacint, 18 years ago

without stl stack we are faster

File size: 35.8 KB
Line 
1// -*- C++ -*-
2#ifndef HUGO_MAX_FLOW_NO_STACK_H
3#define HUGO_MAX_FLOW_NO_STACK_H
4
5#include <vector>
6#include <queue>
7//#include <stack>
8
9#include <hugo/graph_wrapper.h>
10#include <bfs_dfs.h>
11#include <hugo/invalid.h>
12#include <hugo/maps.h>
13#include <hugo/for_each_macros.h>
14
15/// \file
16/// \brief The same as max_flow.h, but without using stl stack for the active nodes. Only for test.
17/// \ingroup galgs
18
19namespace hugo {
20
21  /// \addtogroup galgs
22  /// @{                                                                                                                                       
23  ///Maximum flow algorithms class.
24
25  ///This class provides various algorithms for finding a flow of
26  ///maximum value in a directed graph. The \e source node, the \e
27  ///target node, the \e capacity of the edges and the \e starting \e
28  ///flow value of the edges should be passed to the algorithm through the
29  ///constructor. It is possible to change these quantities using the
30  ///functions \ref resetSource, \ref resetTarget, \ref resetCap and
31  ///\ref resetFlow. Before any subsequent runs of any algorithm of
32  ///the class \ref resetFlow should be called.
33
34  ///After running an algorithm of the class, the actual flow value
35  ///can be obtained by calling \ref flowValue(). The minimum
36  ///value cut can be written into a \c node map of \c bools by
37  ///calling \ref minCut. (\ref minMinCut and \ref maxMinCut writes
38  ///the inclusionwise minimum and maximum of the minimum value
39  ///cuts, resp.)                                                                                                                               
40  ///\param Graph The directed graph type the algorithm runs on.
41  ///\param Num The number type of the capacities and the flow values.
42  ///\param CapMap The capacity map type.
43  ///\param FlowMap The flow map type.                                                                                                           
44  ///\author Marton Makai, Jacint Szabo
45  template <typename Graph, typename Num,
46            typename CapMap=typename Graph::template EdgeMap<Num>,
47            typename FlowMap=typename Graph::template EdgeMap<Num> >
48  class MaxFlowNoStack {
49  protected:
50    typedef typename Graph::Node Node;
51    typedef typename Graph::NodeIt NodeIt;
52    typedef typename Graph::EdgeIt EdgeIt;
53    typedef typename Graph::OutEdgeIt OutEdgeIt;
54    typedef typename Graph::InEdgeIt InEdgeIt;
55
56    //    typedef typename std::vector<std::stack<Node> > VecStack;
57    typedef typename std::vector<Node> VecFirst;
58    typedef typename Graph::template NodeMap<Node> NNMap;
59    typedef typename std::vector<Node> VecNode;
60
61    const Graph* g;
62    Node s;
63    Node t;
64    const CapMap* capacity;
65    FlowMap* flow;
66    int n;      //the number of nodes of G
67    typedef ResGraphWrapper<const Graph, Num, CapMap, FlowMap> ResGW;   
68    //typedef ExpResGraphWrapper<const Graph, Num, CapMap, FlowMap> ResGW;
69    typedef typename ResGW::OutEdgeIt ResGWOutEdgeIt;
70    typedef typename ResGW::Edge ResGWEdge;
71    //typedef typename ResGW::template NodeMap<bool> ReachedMap;
72    typedef typename Graph::template NodeMap<int> ReachedMap;
73
74
75    //level works as a bool map in augmenting path algorithms and is
76    //used by bfs for storing reached information.  In preflow, it
77    //shows the levels of nodes.     
78    ReachedMap level;
79
80    //excess is needed only in preflow
81    typename Graph::template NodeMap<Num> excess;
82
83    //fixme   
84//   protected:
85    //     MaxFlow() { }
86    //     void set(const Graph& _G, Node _s, Node _t, const CapMap& _capacity,
87    //       FlowMap& _flow)
88    //       {
89    //  g=&_G;
90    //  s=_s;
91    //  t=_t;
92    //  capacity=&_capacity;
93    //  flow=&_flow;
94    //  n=_G.nodeNum;
95    //  level.set (_G); //kellene vmi ilyesmi fv
96    //  excess(_G,0); //itt is
97    //       }
98
99    // constants used for heuristics
100    static const int H0=20;
101    static const int H1=1;
102
103  public:
104
105    ///Indicates the property of the starting flow.
106
107    ///Indicates the property of the starting flow. The meanings are as follows:
108    ///- \c ZERO_FLOW: constant zero flow
109    ///- \c GEN_FLOW: any flow, i.e. the sum of the in-flows equals to
110    ///the sum of the out-flows in every node except the \e source and
111    ///the \e target.
112    ///- \c PRE_FLOW: any preflow, i.e. the sum of the in-flows is at
113    ///least the sum of the out-flows in every node except the \e source.
114    ///- \c NO_FLOW: indicates an unspecified edge map. \ref flow will be
115    ///set to the constant zero flow in the beginning of the algorithm in this case.
116    enum FlowEnum{
117      ZERO_FLOW,
118      GEN_FLOW,
119      PRE_FLOW,
120      NO_FLOW
121    };
122
123    enum StatusEnum {
124      AFTER_NOTHING,
125      AFTER_AUGMENTING,
126      AFTER_FAST_AUGMENTING,
127      AFTER_PRE_FLOW_PHASE_1,     
128      AFTER_PRE_FLOW_PHASE_2
129    };
130
131    /// Don not needle this flag only if necessary.
132    StatusEnum status;
133    int number_of_augmentations;
134
135
136    template<typename IntMap>
137    class TrickyReachedMap {
138    protected:
139      IntMap* map;
140      int* number_of_augmentations;
141    public:
142      TrickyReachedMap(IntMap& _map, int& _number_of_augmentations) :
143        map(&_map), number_of_augmentations(&_number_of_augmentations) { }
144      void set(const Node& n, bool b) {
145        if (b)
146          map->set(n, *number_of_augmentations);
147        else
148          map->set(n, *number_of_augmentations-1);
149      }
150      bool operator[](const Node& n) const {
151        return (*map)[n]==*number_of_augmentations;
152      }
153    };
154   
155    ///Constructor
156
157    ///\todo Document, please.
158    ///
159    MaxFlowNoStack(const Graph& _G, Node _s, Node _t, const CapMap& _capacity,
160            FlowMap& _flow) :
161      g(&_G), s(_s), t(_t), capacity(&_capacity),
162      flow(&_flow), n(_G.nodeNum()), level(_G), excess(_G,0),
163      status(AFTER_NOTHING), number_of_augmentations(0) { }
164
165    ///Runs a maximum flow algorithm.
166
167    ///Runs a preflow algorithm, which is the fastest maximum flow
168    ///algorithm up-to-date. The default for \c fe is ZERO_FLOW.
169    ///\pre The starting flow must be
170    /// - a constant zero flow if \c fe is \c ZERO_FLOW,
171    /// - an arbitary flow if \c fe is \c GEN_FLOW,
172    /// - an arbitary preflow if \c fe is \c PRE_FLOW,
173    /// - any map if \c fe is NO_FLOW.
174    void run(FlowEnum fe=ZERO_FLOW) {
175      preflow(fe);
176    }
177
178                                                                             
179    ///Runs a preflow algorithm. 
180
181    ///Runs a preflow algorithm. The preflow algorithms provide the
182    ///fastest way to compute a maximum flow in a directed graph.
183    ///\pre The starting flow must be
184    /// - a constant zero flow if \c fe is \c ZERO_FLOW,
185    /// - an arbitary flow if \c fe is \c GEN_FLOW,
186    /// - an arbitary preflow if \c fe is \c PRE_FLOW,
187    /// - any map if \c fe is NO_FLOW.
188    ///
189    ///\todo NO_FLOW should be the default flow.
190    void preflow(FlowEnum fe) {
191      preflowPhase1(fe);
192      preflowPhase2();
193    }
194    // Heuristics:
195    //   2 phase
196    //   gap
197    //   list 'level_list' on the nodes on level i implemented by hand
198    //   stack 'active' on the active nodes on level i                                                                                   
199    //   runs heuristic 'highest label' for H1*n relabels
200    //   runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'
201    //   Parameters H0 and H1 are initialized to 20 and 1.
202
203    ///Runs the first phase of the preflow algorithm.
204
205    ///The preflow algorithm consists of two phases, this method runs the
206    ///first phase. After the first phase the maximum flow value and a
207    ///minimum value cut can already be computed, though a maximum flow
208    ///is net yet obtained. So after calling this method \ref flowValue
209    ///and \ref actMinCut gives proper results.
210    ///\warning: \ref minCut, \ref minMinCut and \ref maxMinCut do not
211    ///give minimum value cuts unless calling \ref preflowPhase2.
212    ///\pre The starting flow must be
213    /// - a constant zero flow if \c fe is \c ZERO_FLOW,
214    /// - an arbitary flow if \c fe is \c GEN_FLOW,
215    /// - an arbitary preflow if \c fe is \c PRE_FLOW,
216    /// - any map if \c fe is NO_FLOW.
217    void preflowPhase1(FlowEnum fe);
218
219    ///Runs the second phase of the preflow algorithm.
220
221    ///The preflow algorithm consists of two phases, this method runs
222    ///the second phase. After calling \ref preflowPhase1 and then
223    ///\ref preflowPhase2 the methods \ref flowValue, \ref minCut,
224    ///\ref minMinCut and \ref maxMinCut give proper results.
225    ///\pre \ref preflowPhase1 must be called before.
226    void preflowPhase2();
227
228    /// Starting from a flow, this method searches for an augmenting path
229    /// according to the Edmonds-Karp algorithm
230    /// and augments the flow on if any.
231    /// The return value shows if the augmentation was succesful.
232    bool augmentOnShortestPath();
233    bool augmentOnShortestPath2();
234
235    /// Starting from a flow, this method searches for an augmenting blocking
236    /// flow according to Dinits' algorithm and augments the flow on if any.
237    /// The blocking flow is computed in a physically constructed
238    /// residual graph of type \c Mutablegraph.
239    /// The return value show sif the augmentation was succesful.
240    template<typename MutableGraph> bool augmentOnBlockingFlow();
241
242    /// The same as \c augmentOnBlockingFlow<MutableGraph> but the
243    /// residual graph is not constructed physically.
244    /// The return value shows if the augmentation was succesful.
245    bool augmentOnBlockingFlow2();
246
247    /// Returns the maximum value of a flow.
248
249    /// Returns the maximum value of a flow, by counting the
250    /// over-flow of the target node \ref t.
251    /// It can be called already after running \ref preflowPhase1.
252    Num flowValue() const {
253      Num a=0;
254      FOR_EACH_INC_LOC(InEdgeIt, e, *g, t) a+=(*flow)[e];
255      FOR_EACH_INC_LOC(OutEdgeIt, e, *g, t) a-=(*flow)[e];
256      return a;
257      //marci figyu: excess[t] epp ezt adja preflow 1. fazisa utan   
258    }
259
260    ///Returns a minimum value cut after calling \ref preflowPhase1.
261
262    ///After the first phase of the preflow algorithm the maximum flow
263    ///value and a minimum value cut can already be computed. This
264    ///method can be called after running \ref preflowPhase1 for
265    ///obtaining a minimum value cut.
266    /// \warning Gives proper result only right after calling \ref
267    /// preflowPhase1.
268    /// \todo We have to make some status variable which shows the
269    /// actual state
270    /// of the class. This enables us to determine which methods are valid
271    /// for MinCut computation
272    template<typename _CutMap>
273    void actMinCut(_CutMap& M) const {
274      NodeIt v;
275      switch (status) {
276      case AFTER_PRE_FLOW_PHASE_1:
277        for(g->first(v); g->valid(v); g->next(v)) {
278          if (level[v] < n) {
279            M.set(v, false);
280          } else {
281            M.set(v, true);
282          }
283        }
284        break;
285      case AFTER_PRE_FLOW_PHASE_2:
286      case AFTER_NOTHING:
287        minMinCut(M);
288        break;
289      case AFTER_AUGMENTING:
290        for(g->first(v); g->valid(v); g->next(v)) {
291          if (level[v]) {
292            M.set(v, true);
293          } else {
294            M.set(v, false);
295          }
296        }
297        break;
298      case AFTER_FAST_AUGMENTING:
299        for(g->first(v); g->valid(v); g->next(v)) {
300          if (level[v]==number_of_augmentations) {
301            M.set(v, true);
302          } else {
303            M.set(v, false);
304          }
305        }
306        break;
307      }
308    }
309
310    ///Returns the inclusionwise minimum of the minimum value cuts.
311
312    ///Sets \c M to the characteristic vector of the minimum value cut
313    ///which is inclusionwise minimum. It is computed by processing
314    ///a bfs from the source node \c s in the residual graph.
315    ///\pre M should be a node map of bools initialized to false.
316    ///\pre \c flow must be a maximum flow.
317    template<typename _CutMap>
318    void minMinCut(_CutMap& M) const {
319      std::queue<Node> queue;
320
321      M.set(s,true);
322      queue.push(s);
323
324      while (!queue.empty()) {
325        Node w=queue.front();
326        queue.pop();
327
328        OutEdgeIt e;
329        for(g->first(e,w) ; g->valid(e); g->next(e)) {
330          Node v=g->head(e);
331          if (!M[v] && (*flow)[e] < (*capacity)[e] ) {
332            queue.push(v);
333            M.set(v, true);
334          }
335        }
336
337        InEdgeIt f;
338        for(g->first(f,w) ; g->valid(f); g->next(f)) {
339          Node v=g->tail(f);
340          if (!M[v] && (*flow)[f] > 0 ) {
341            queue.push(v);
342            M.set(v, true);
343          }
344        }
345      }
346    }
347
348    ///Returns the inclusionwise maximum of the minimum value cuts.
349
350    ///Sets \c M to the characteristic vector of the minimum value cut
351    ///which is inclusionwise maximum. It is computed by processing a
352    ///backward bfs from the target node \c t in the residual graph.
353    ///\pre M should be a node map of bools initialized to false.
354    ///\pre \c flow must be a maximum flow.
355    template<typename _CutMap>
356    void maxMinCut(_CutMap& M) const {
357
358      NodeIt v;
359      for(g->first(v) ; g->valid(v); g->next(v)) {
360        M.set(v, true);
361      }
362
363      std::queue<Node> queue;
364
365      M.set(t,false);
366      queue.push(t);
367
368      while (!queue.empty()) {
369        Node w=queue.front();
370        queue.pop();
371
372        InEdgeIt e;
373        for(g->first(e,w) ; g->valid(e); g->next(e)) {
374          Node v=g->tail(e);
375          if (M[v] && (*flow)[e] < (*capacity)[e] ) {
376            queue.push(v);
377            M.set(v, false);
378          }
379        }
380
381        OutEdgeIt f;
382        for(g->first(f,w) ; g->valid(f); g->next(f)) {
383          Node v=g->head(f);
384          if (M[v] && (*flow)[f] > 0 ) {
385            queue.push(v);
386            M.set(v, false);
387          }
388        }
389      }
390    }
391
392    ///Returns a minimum value cut.
393
394    ///Sets \c M to the characteristic vector of a minimum value cut.
395    ///\pre M should be a node map of bools initialized to false.
396    ///\pre \c flow must be a maximum flow.   
397    template<typename CutMap>
398    void minCut(CutMap& M) const { minMinCut(M); }
399
400    ///Resets the source node to \c _s.
401
402    ///Resets the source node to \c _s.
403    ///
404    void resetSource(Node _s) { s=_s; status=AFTER_NOTHING; }
405
406    ///Resets the target node to \c _t.
407
408    ///Resets the target node to \c _t.
409    ///
410    void resetTarget(Node _t) { t=_t; status=AFTER_NOTHING; }
411
412    /// Resets the edge map of the capacities to _cap.
413
414    /// Resets the edge map of the capacities to _cap.
415    ///
416    void resetCap(const CapMap& _cap) { capacity=&_cap; status=AFTER_NOTHING; }
417
418    /// Resets the edge map of the flows to _flow.
419
420    /// Resets the edge map of the flows to _flow.
421    ///
422    void resetFlow(FlowMap& _flow) { flow=&_flow; status=AFTER_NOTHING; }
423
424
425  private:
426
427    int push(Node w, NNMap& next, VecFirst& first) {
428
429      int lev=level[w];
430      Num exc=excess[w];
431      int newlevel=n;       //bound on the next level of w
432
433      OutEdgeIt e;
434      for(g->first(e,w); g->valid(e); g->next(e)) {
435
436        if ( (*flow)[e] >= (*capacity)[e] ) continue;
437        Node v=g->head(e);
438
439        if( lev > level[v] ) { //Push is allowed now
440
441          if ( excess[v]<=0 && v!=t && v!=s ) {
442            next.set(v,first[level[v]]);
443            first[level[v]]=v;
444            //      int lev_v=level[v];
445            //active[lev_v].push(v);
446          }
447
448          Num cap=(*capacity)[e];
449          Num flo=(*flow)[e];
450          Num remcap=cap-flo;
451
452          if ( remcap >= exc ) { //A nonsaturating push.
453
454            flow->set(e, flo+exc);
455            excess.set(v, excess[v]+exc);
456            exc=0;
457            break;
458
459          } else { //A saturating push.
460            flow->set(e, cap);
461            excess.set(v, excess[v]+remcap);
462            exc-=remcap;
463          }
464        } else if ( newlevel > level[v] ) newlevel = level[v];
465      } //for out edges wv
466
467      if ( exc > 0 ) {
468        InEdgeIt e;
469        for(g->first(e,w); g->valid(e); g->next(e)) {
470
471          if( (*flow)[e] <= 0 ) continue;
472          Node v=g->tail(e);
473
474          if( lev > level[v] ) { //Push is allowed now
475
476            if ( excess[v]<=0 && v!=t && v!=s ) {
477              next.set(v,first[level[v]]);
478              first[level[v]]=v;
479              //int lev_v=level[v];
480              //active[lev_v].push(v);
481            }
482
483            Num flo=(*flow)[e];
484
485            if ( flo >= exc ) { //A nonsaturating push.
486
487              flow->set(e, flo-exc);
488              excess.set(v, excess[v]+exc);
489              exc=0;
490              break;
491            } else {  //A saturating push.
492
493              excess.set(v, excess[v]+flo);
494              exc-=flo;
495              flow->set(e,0);
496            }
497          } else if ( newlevel > level[v] ) newlevel = level[v];
498        } //for in edges vw
499
500      } // if w still has excess after the out edge for cycle
501
502      excess.set(w, exc);
503
504      return newlevel;
505    }
506
507
508    void preflowPreproc(FlowEnum fe, NNMap& next, VecFirst& first,
509                        VecNode& level_list, NNMap& left, NNMap& right)
510    {
511      std::queue<Node> bfs_queue;
512
513      switch (fe) {
514      case NO_FLOW:   //flow is already set to const zero in this case
515      case ZERO_FLOW:
516        {
517          //Reverse_bfs from t, to find the starting level.
518          level.set(t,0);
519          bfs_queue.push(t);
520
521          while (!bfs_queue.empty()) {
522
523            Node v=bfs_queue.front();
524            bfs_queue.pop();
525            int l=level[v]+1;
526
527            InEdgeIt e;
528            for(g->first(e,v); g->valid(e); g->next(e)) {
529              Node w=g->tail(e);
530              if ( level[w] == n && w != s ) {
531                bfs_queue.push(w);
532                Node z=level_list[l];
533                if ( g->valid(z) ) left.set(z,w);
534                right.set(w,z);
535                level_list[l]=w;
536                level.set(w, l);
537              }
538            }
539          }
540
541          //the starting flow
542          OutEdgeIt e;
543          for(g->first(e,s); g->valid(e); g->next(e))
544            {
545              Num c=(*capacity)[e];
546              if ( c <= 0 ) continue;
547              Node w=g->head(e);
548              if ( level[w] < n ) {
549                if ( excess[w] <= 0 && w!=t )
550                  {
551                    next.set(w,first[level[w]]);
552                    first[level[w]]=w;
553                    //active[level[w]].push(w);
554                  }
555                flow->set(e, c);
556                excess.set(w, excess[w]+c);
557              }
558            }
559          break;
560        }
561
562      case GEN_FLOW:
563      case PRE_FLOW:
564        {
565          //Reverse_bfs from t in the residual graph,
566          //to find the starting level.
567          level.set(t,0);
568          bfs_queue.push(t);
569
570          while (!bfs_queue.empty()) {
571
572            Node v=bfs_queue.front();
573            bfs_queue.pop();
574            int l=level[v]+1;
575
576            InEdgeIt e;
577            for(g->first(e,v); g->valid(e); g->next(e)) {
578              if ( (*capacity)[e] <= (*flow)[e] ) continue;
579              Node w=g->tail(e);
580              if ( level[w] == n && w != s ) {
581                bfs_queue.push(w);
582                Node z=level_list[l];
583                if ( g->valid(z) ) left.set(z,w);
584                right.set(w,z);
585                level_list[l]=w;
586                level.set(w, l);
587              }
588            }
589
590            OutEdgeIt f;
591            for(g->first(f,v); g->valid(f); g->next(f)) {
592              if ( 0 >= (*flow)[f] ) continue;
593              Node w=g->head(f);
594              if ( level[w] == n && w != s ) {
595                bfs_queue.push(w);
596                Node z=level_list[l];
597                if ( g->valid(z) ) left.set(z,w);
598                right.set(w,z);
599                level_list[l]=w;
600                level.set(w, l);
601              }
602            }
603          }
604
605
606          //the starting flow
607          OutEdgeIt e;
608          for(g->first(e,s); g->valid(e); g->next(e))
609            {
610              Num rem=(*capacity)[e]-(*flow)[e];
611              if ( rem <= 0 ) continue;
612              Node w=g->head(e);
613              if ( level[w] < n ) {
614                if ( excess[w] <= 0 && w!=t )
615                  {
616                    next.set(w,first[level[w]]);
617                    first[level[w]]=w;
618                    //active[level[w]].push(w);
619                  }   
620                flow->set(e, (*capacity)[e]);
621                excess.set(w, excess[w]+rem);
622              }
623            }
624
625          InEdgeIt f;
626          for(g->first(f,s); g->valid(f); g->next(f))
627            {
628              if ( (*flow)[f] <= 0 ) continue;
629              Node w=g->tail(f);
630              if ( level[w] < n ) {
631                if ( excess[w] <= 0 && w!=t )
632                  {
633                    next.set(w,first[level[w]]);
634                    first[level[w]]=w;
635                    //active[level[w]].push(w);
636                  }   
637                excess.set(w, excess[w]+(*flow)[f]);
638                flow->set(f, 0);
639              }
640            }
641          break;
642        } //case PRE_FLOW
643      }
644    } //preflowPreproc
645
646
647
648    void relabel(Node w, int newlevel, NNMap& next, VecFirst& first,
649                 VecNode& level_list, NNMap& left,
650                 NNMap& right, int& b, int& k, bool what_heur )
651    {
652
653      Num lev=level[w];
654
655      Node right_n=right[w];
656      Node left_n=left[w];
657
658      //unlacing starts
659      if ( g->valid(right_n) ) {
660        if ( g->valid(left_n) ) {
661          right.set(left_n, right_n);
662          left.set(right_n, left_n);
663        } else {
664          level_list[lev]=right_n;
665          left.set(right_n, INVALID);
666        }
667      } else {
668        if ( g->valid(left_n) ) {
669          right.set(left_n, INVALID);
670        } else {
671          level_list[lev]=INVALID;
672        }
673      }
674      //unlacing ends
675
676      if ( !g->valid(level_list[lev]) ) {
677
678        //gapping starts
679        for (int i=lev; i!=k ; ) {
680          Node v=level_list[++i];
681          while ( g->valid(v) ) {
682            level.set(v,n);
683            v=right[v];
684          }
685          level_list[i]=INVALID;
686          if ( !what_heur ) first[i]=INVALID;
687          /*{
688            while ( !active[i].empty() ) {
689            active[i].pop();    //FIXME: ezt szebben kene
690            }
691            }*/
692        }
693
694        level.set(w,n);
695        b=lev-1;
696        k=b;
697        //gapping ends
698
699      } else {
700
701        if ( newlevel == n ) level.set(w,n);
702        else {
703          level.set(w,++newlevel);
704          next.set(w,first[newlevel]);
705          first[newlevel]=w;
706          //      active[newlevel].push(w);
707          if ( what_heur ) b=newlevel;
708          if ( k < newlevel ) ++k;      //now k=newlevel
709          Node z=level_list[newlevel];
710          if ( g->valid(z) ) left.set(z,w);
711          right.set(w,z);
712          left.set(w,INVALID);
713          level_list[newlevel]=w;
714        }
715      }
716
717    } //relabel
718
719
720    template<typename MapGraphWrapper>
721    class DistanceMap {
722    protected:
723      const MapGraphWrapper* g;
724      typename MapGraphWrapper::template NodeMap<int> dist;
725    public:
726      DistanceMap(MapGraphWrapper& _g) : g(&_g), dist(*g, g->nodeNum()) { }
727      void set(const typename MapGraphWrapper::Node& n, int a) {
728        dist.set(n, a);
729      }
730      int operator[](const typename MapGraphWrapper::Node& n) const {
731        return dist[n];
732      }
733      //       int get(const typename MapGraphWrapper::Node& n) const {
734      //        return dist[n]; }
735      //       bool get(const typename MapGraphWrapper::Edge& e) const {
736      //        return (dist.get(g->tail(e))<dist.get(g->head(e))); }
737      bool operator[](const typename MapGraphWrapper::Edge& e) const {
738        return (dist[g->tail(e)]<dist[g->head(e)]);
739      }
740    };
741
742  };
743
744
745  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
746  void MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::preflowPhase1(FlowEnum fe)
747  {
748
749    int heur0=(int)(H0*n);  //time while running 'bound decrease'
750    int heur1=(int)(H1*n);  //time while running 'highest label'
751    int heur=heur1;         //starting time interval (#of relabels)
752    int numrelabel=0;
753
754    bool what_heur=1;
755    //It is 0 in case 'bound decrease' and 1 in case 'highest label'
756
757    bool end=false;
758    //Needed for 'bound decrease', true means no active nodes are above bound
759    //b.
760
761    int k=n-2;  //bound on the highest level under n containing a node
762    int b=k;    //bound on the highest level under n of an active node
763
764    VecFirst first(n, INVALID);
765    NNMap next(*g, INVALID); //maybe INVALID is not needed
766    //    VecStack active(n);
767
768    NNMap left(*g, INVALID);
769    NNMap right(*g, INVALID);
770    VecNode level_list(n,INVALID);
771    //List of the nodes in level i<n, set to n.
772
773    NodeIt v;
774    for(g->first(v); g->valid(v); g->next(v)) level.set(v,n);
775    //setting each node to level n
776
777    if ( fe == NO_FLOW ) {
778      EdgeIt e;
779      for(g->first(e); g->valid(e); g->next(e)) flow->set(e,0);
780    }
781
782    switch (fe) { //computing the excess
783    case PRE_FLOW:
784      {
785        NodeIt v;
786        for(g->first(v); g->valid(v); g->next(v)) {
787          Num exc=0;
788
789          InEdgeIt e;
790          for(g->first(e,v); g->valid(e); g->next(e)) exc+=(*flow)[e];
791          OutEdgeIt f;
792          for(g->first(f,v); g->valid(f); g->next(f)) exc-=(*flow)[f];
793
794          excess.set(v,exc);
795
796          //putting the active nodes into the stack
797          int lev=level[v];
798          if ( exc > 0 && lev < n && v != t )
799            {
800              next.set(v,first[lev]);
801              first[lev]=v;
802            }
803          //      active[lev].push(v);
804        }
805        break;
806      }
807    case GEN_FLOW:
808      {
809        NodeIt v;
810        for(g->first(v); g->valid(v); g->next(v)) excess.set(v,0);
811
812        Num exc=0;
813        InEdgeIt e;
814        for(g->first(e,t); g->valid(e); g->next(e)) exc+=(*flow)[e];
815        OutEdgeIt f;
816        for(g->first(f,t); g->valid(f); g->next(f)) exc-=(*flow)[f];
817        excess.set(t,exc);
818        break;
819      }
820    case ZERO_FLOW:
821    case NO_FLOW:
822      {
823        NodeIt v;
824        for(g->first(v); g->valid(v); g->next(v)) excess.set(v,0);
825        break;
826      }
827    }
828
829    preflowPreproc(fe, next, first,/*active*/ level_list, left, right);
830    //End of preprocessing
831
832
833    //Push/relabel on the highest level active nodes.
834    while ( true ) {
835      if ( b == 0 ) {
836        if ( !what_heur && !end && k > 0 ) {
837          b=k;
838          end=true;
839        } else break;
840      }
841
842      if ( !g->valid(first[b])/*active[b].empty()*/ ) --b;
843      else {
844        end=false;
845        Node w=first[b];
846        first[b]=next[w];
847        /*      Node w=active[b].top();
848                active[b].pop();*/
849        int newlevel=push(w,/*active*/next, first);
850        if ( excess[w] > 0 ) relabel(w, newlevel, /*active*/next, first, level_list,
851                                     left, right, b, k, what_heur);
852
853        ++numrelabel;
854        if ( numrelabel >= heur ) {
855          numrelabel=0;
856          if ( what_heur ) {
857            what_heur=0;
858            heur=heur0;
859            end=false;
860          } else {
861            what_heur=1;
862            heur=heur1;
863            b=k;
864          }
865        }
866      }
867    }
868
869    status=AFTER_PRE_FLOW_PHASE_1;
870  }
871
872
873
874  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
875  void MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::preflowPhase2()
876  {
877
878    int k=n-2;  //bound on the highest level under n containing a node
879    int b=k;    //bound on the highest level under n of an active node
880
881   
882    VecFirst first(n, INVALID);
883    NNMap next(*g, INVALID); //maybe INVALID is not needed
884    //    VecStack active(n);
885    level.set(s,0);
886    std::queue<Node> bfs_queue;
887    bfs_queue.push(s);
888
889    while (!bfs_queue.empty()) {
890
891      Node v=bfs_queue.front();
892      bfs_queue.pop();
893      int l=level[v]+1;
894
895      InEdgeIt e;
896      for(g->first(e,v); g->valid(e); g->next(e)) {
897        if ( (*capacity)[e] <= (*flow)[e] ) continue;
898        Node u=g->tail(e);
899        if ( level[u] >= n ) {
900          bfs_queue.push(u);
901          level.set(u, l);
902          if ( excess[u] > 0 ) {
903            next.set(u,first[l]);
904            first[l]=u;
905            //active[l].push(u);
906          }
907        }
908      }
909
910      OutEdgeIt f;
911      for(g->first(f,v); g->valid(f); g->next(f)) {
912        if ( 0 >= (*flow)[f] ) continue;
913        Node u=g->head(f);
914        if ( level[u] >= n ) {
915          bfs_queue.push(u);
916          level.set(u, l);
917          if ( excess[u] > 0 ) {
918            next.set(u,first[l]);
919            first[l]=u;
920            //active[l].push(u);
921          }
922        }
923      }
924    }
925    b=n-2;
926
927    while ( true ) {
928
929      if ( b == 0 ) break;
930
931      if ( !g->valid(first[b])/*active[b].empty()*/ ) --b;
932      else {
933
934        Node w=first[b];
935        first[b]=next[w];
936        /*      Node w=active[b].top();
937                active[b].pop();*/
938        int newlevel=push(w,next, first/*active*/);
939
940        //relabel
941        if ( excess[w] > 0 ) {
942          level.set(w,++newlevel);
943          next.set(w,first[newlevel]);
944          first[newlevel]=w;
945          //active[newlevel].push(w);
946          b=newlevel;
947        }
948      }  // if stack[b] is nonempty
949    } // while(true)
950
951    status=AFTER_PRE_FLOW_PHASE_2;
952  }
953
954
955
956  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
957  bool MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath()
958  {
959    ResGW res_graph(*g, *capacity, *flow);
960    bool _augment=false;
961
962    //ReachedMap level(res_graph);
963    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
964    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
965    bfs.pushAndSetReached(s);
966
967    typename ResGW::template NodeMap<ResGWEdge> pred(res_graph);
968    pred.set(s, INVALID);
969
970    typename ResGW::template NodeMap<Num> free(res_graph);
971
972    //searching for augmenting path
973    while ( !bfs.finished() ) {
974      ResGWOutEdgeIt e=bfs;
975      if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
976        Node v=res_graph.tail(e);
977        Node w=res_graph.head(e);
978        pred.set(w, e);
979        if (res_graph.valid(pred[v])) {
980          free.set(w, std::min(free[v], res_graph.resCap(e)));
981        } else {
982          free.set(w, res_graph.resCap(e));
983        }
984        if (res_graph.head(e)==t) { _augment=true; break; }
985      }
986
987      ++bfs;
988    } //end of searching augmenting path
989
990    if (_augment) {
991      Node n=t;
992      Num augment_value=free[t];
993      while (res_graph.valid(pred[n])) {
994        ResGWEdge e=pred[n];
995        res_graph.augment(e, augment_value);
996        n=res_graph.tail(e);
997      }
998    }
999
1000    status=AFTER_AUGMENTING;
1001    return _augment;
1002  }
1003
1004
1005  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
1006  bool MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath2()
1007  {
1008    ResGW res_graph(*g, *capacity, *flow);
1009    bool _augment=false;
1010
1011    if (status!=AFTER_FAST_AUGMENTING) {
1012      FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
1013      number_of_augmentations=1;
1014    } else {
1015      ++number_of_augmentations;
1016    }
1017    TrickyReachedMap<ReachedMap>
1018      tricky_reached_map(level, number_of_augmentations);
1019    //ReachedMap level(res_graph);
1020//    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
1021    BfsIterator<ResGW, TrickyReachedMap<ReachedMap> >
1022      bfs(res_graph, tricky_reached_map);
1023    bfs.pushAndSetReached(s);
1024
1025    typename ResGW::template NodeMap<ResGWEdge> pred(res_graph);
1026    pred.set(s, INVALID);
1027
1028    typename ResGW::template NodeMap<Num> free(res_graph);
1029
1030    //searching for augmenting path
1031    while ( !bfs.finished() ) {
1032      ResGWOutEdgeIt e=bfs;
1033      if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
1034        Node v=res_graph.tail(e);
1035        Node w=res_graph.head(e);
1036        pred.set(w, e);
1037        if (res_graph.valid(pred[v])) {
1038          free.set(w, std::min(free[v], res_graph.resCap(e)));
1039        } else {
1040          free.set(w, res_graph.resCap(e));
1041        }
1042        if (res_graph.head(e)==t) { _augment=true; break; }
1043      }
1044
1045      ++bfs;
1046    } //end of searching augmenting path
1047
1048    if (_augment) {
1049      Node n=t;
1050      Num augment_value=free[t];
1051      while (res_graph.valid(pred[n])) {
1052        ResGWEdge e=pred[n];
1053        res_graph.augment(e, augment_value);
1054        n=res_graph.tail(e);
1055      }
1056    }
1057
1058    status=AFTER_FAST_AUGMENTING;
1059    return _augment;
1060  }
1061
1062
1063  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
1064  template<typename MutableGraph>
1065  bool MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow()
1066  {
1067    typedef MutableGraph MG;
1068    bool _augment=false;
1069
1070    ResGW res_graph(*g, *capacity, *flow);
1071
1072    //bfs for distances on the residual graph
1073    //ReachedMap level(res_graph);
1074    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
1075    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
1076    bfs.pushAndSetReached(s);
1077    typename ResGW::template NodeMap<int>
1078      dist(res_graph); //filled up with 0's
1079
1080    //F will contain the physical copy of the residual graph
1081    //with the set of edges which are on shortest paths
1082    MG F;
1083    typename ResGW::template NodeMap<typename MG::Node>
1084      res_graph_to_F(res_graph);
1085    {
1086      typename ResGW::NodeIt n;
1087      for(res_graph.first(n); res_graph.valid(n); res_graph.next(n)) {
1088        res_graph_to_F.set(n, F.addNode());
1089      }
1090    }
1091
1092    typename MG::Node sF=res_graph_to_F[s];
1093    typename MG::Node tF=res_graph_to_F[t];
1094    typename MG::template EdgeMap<ResGWEdge> original_edge(F);
1095    typename MG::template EdgeMap<Num> residual_capacity(F);
1096
1097    while ( !bfs.finished() ) {
1098      ResGWOutEdgeIt e=bfs;
1099      if (res_graph.valid(e)) {
1100        if (bfs.isBNodeNewlyReached()) {
1101          dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
1102          typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)],
1103                                        res_graph_to_F[res_graph.head(e)]);
1104          original_edge.update();
1105          original_edge.set(f, e);
1106          residual_capacity.update();
1107          residual_capacity.set(f, res_graph.resCap(e));
1108        } else {
1109          if (dist[res_graph.head(e)]==(dist[res_graph.tail(e)]+1)) {
1110            typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)],
1111                                          res_graph_to_F[res_graph.head(e)]);
1112            original_edge.update();
1113            original_edge.set(f, e);
1114            residual_capacity.update();
1115            residual_capacity.set(f, res_graph.resCap(e));
1116          }
1117        }
1118      }
1119      ++bfs;
1120    } //computing distances from s in the residual graph
1121
1122    bool __augment=true;
1123
1124    while (__augment) {
1125      __augment=false;
1126      //computing blocking flow with dfs
1127      DfsIterator< MG, typename MG::template NodeMap<bool> > dfs(F);
1128      typename MG::template NodeMap<typename MG::Edge> pred(F);
1129      pred.set(sF, INVALID);
1130      //invalid iterators for sources
1131
1132      typename MG::template NodeMap<Num> free(F);
1133
1134      dfs.pushAndSetReached(sF);
1135      while (!dfs.finished()) {
1136        ++dfs;
1137        if (F.valid(/*typename MG::OutEdgeIt*/(dfs))) {
1138          if (dfs.isBNodeNewlyReached()) {
1139            typename MG::Node v=F.aNode(dfs);
1140            typename MG::Node w=F.bNode(dfs);
1141            pred.set(w, dfs);
1142            if (F.valid(pred[v])) {
1143              free.set(w, std::min(free[v], residual_capacity[dfs]));
1144            } else {
1145              free.set(w, residual_capacity[dfs]);
1146            }
1147            if (w==tF) {
1148              __augment=true;
1149              _augment=true;
1150              break;
1151            }
1152
1153          } else {
1154            F.erase(/*typename MG::OutEdgeIt*/(dfs));
1155          }
1156        }
1157      }
1158
1159      if (__augment) {
1160        typename MG::Node n=tF;
1161        Num augment_value=free[tF];
1162        while (F.valid(pred[n])) {
1163          typename MG::Edge e=pred[n];
1164          res_graph.augment(original_edge[e], augment_value);
1165          n=F.tail(e);
1166          if (residual_capacity[e]==augment_value)
1167            F.erase(e);
1168          else
1169            residual_capacity.set(e, residual_capacity[e]-augment_value);
1170        }
1171      }
1172
1173    }
1174
1175    status=AFTER_AUGMENTING;
1176    return _augment;
1177  }
1178
1179
1180
1181
1182  template <typename Graph, typename Num, typename CapMap, typename FlowMap>
1183  bool MaxFlowNoStack<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow2()
1184  {
1185    bool _augment=false;
1186
1187    ResGW res_graph(*g, *capacity, *flow);
1188
1189    //ReachedMap level(res_graph);
1190    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
1191    BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
1192
1193    bfs.pushAndSetReached(s);
1194    DistanceMap<ResGW> dist(res_graph);
1195    while ( !bfs.finished() ) {
1196      ResGWOutEdgeIt e=bfs;
1197      if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {
1198        dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
1199      }
1200      ++bfs;
1201    } //computing distances from s in the residual graph
1202
1203      //Subgraph containing the edges on some shortest paths
1204    ConstMap<typename ResGW::Node, bool> true_map(true);
1205    typedef SubGraphWrapper<ResGW, ConstMap<typename ResGW::Node, bool>,
1206      DistanceMap<ResGW> > FilterResGW;
1207    FilterResGW filter_res_graph(res_graph, true_map, dist);
1208
1209    //Subgraph, which is able to delete edges which are already
1210    //met by the dfs
1211    typename FilterResGW::template NodeMap<typename FilterResGW::OutEdgeIt>
1212      first_out_edges(filter_res_graph);
1213    typename FilterResGW::NodeIt v;
1214    for(filter_res_graph.first(v); filter_res_graph.valid(v);
1215        filter_res_graph.next(v))
1216      {
1217        typename FilterResGW::OutEdgeIt e;
1218        filter_res_graph.first(e, v);
1219        first_out_edges.set(v, e);
1220      }
1221    typedef ErasingFirstGraphWrapper<FilterResGW, typename FilterResGW::
1222      template NodeMap<typename FilterResGW::OutEdgeIt> > ErasingResGW;
1223    ErasingResGW erasing_res_graph(filter_res_graph, first_out_edges);
1224
1225    bool __augment=true;
1226
1227    while (__augment) {
1228
1229      __augment=false;
1230      //computing blocking flow with dfs
1231      DfsIterator< ErasingResGW,
1232        typename ErasingResGW::template NodeMap<bool> >
1233        dfs(erasing_res_graph);
1234      typename ErasingResGW::
1235        template NodeMap<typename ErasingResGW::OutEdgeIt>
1236        pred(erasing_res_graph);
1237      pred.set(s, INVALID);
1238      //invalid iterators for sources
1239
1240      typename ErasingResGW::template NodeMap<Num>
1241        free1(erasing_res_graph);
1242
1243      dfs.pushAndSetReached
1244        ///\bug hugo 0.2
1245        (typename ErasingResGW::Node
1246         (typename FilterResGW::Node
1247          (typename ResGW::Node(s)
1248           )
1249          )
1250         );
1251      while (!dfs.finished()) {
1252        ++dfs;
1253        if (erasing_res_graph.valid(typename ErasingResGW::OutEdgeIt(dfs)))
1254          {
1255            if (dfs.isBNodeNewlyReached()) {
1256
1257              typename ErasingResGW::Node v=erasing_res_graph.aNode(dfs);
1258              typename ErasingResGW::Node w=erasing_res_graph.bNode(dfs);
1259
1260              pred.set(w, /*typename ErasingResGW::OutEdgeIt*/(dfs));
1261              if (erasing_res_graph.valid(pred[v])) {
1262                free1.set
1263                  (w, std::min(free1[v], res_graph.resCap
1264                               (typename ErasingResGW::OutEdgeIt(dfs))));
1265              } else {
1266                free1.set
1267                  (w, res_graph.resCap
1268                   (typename ErasingResGW::OutEdgeIt(dfs)));
1269              }
1270
1271              if (w==t) {
1272                __augment=true;
1273                _augment=true;
1274                break;
1275              }
1276            } else {
1277              erasing_res_graph.erase(dfs);
1278            }
1279          }
1280      }
1281
1282      if (__augment) {
1283        typename ErasingResGW::Node
1284          n=typename FilterResGW::Node(typename ResGW::Node(t));
1285        //        typename ResGW::NodeMap<Num> a(res_graph);
1286        //        typename ResGW::Node b;
1287        //        Num j=a[b];
1288        //        typename FilterResGW::NodeMap<Num> a1(filter_res_graph);
1289        //        typename FilterResGW::Node b1;
1290        //        Num j1=a1[b1];
1291        //        typename ErasingResGW::NodeMap<Num> a2(erasing_res_graph);
1292        //        typename ErasingResGW::Node b2;
1293        //        Num j2=a2[b2];
1294        Num augment_value=free1[n];
1295        while (erasing_res_graph.valid(pred[n])) {
1296          typename ErasingResGW::OutEdgeIt e=pred[n];
1297          res_graph.augment(e, augment_value);
1298          n=erasing_res_graph.tail(e);
1299          if (res_graph.resCap(e)==0)
1300            erasing_res_graph.erase(e);
1301        }
1302      }
1303
1304    } //while (__augment)
1305
1306    status=AFTER_AUGMENTING;
1307    return _augment;
1308  }
1309
1310
1311} //namespace hugo
1312
1313#endif //HUGO_MAX_FLOW_H
1314
1315
1316
1317
Note: See TracBrowser for help on using the repository browser.