src/work/marci/max_bipartite_matching.h
author alpar
Mon, 21 Feb 2005 14:59:12 +0000
changeset 1164 80bb73097736
parent 768 a5e9303a5511
permissions -rw-r--r--
A year has passed again.
     1 // -*- c++ -*-
     2 #ifndef LEMON_MAX_BIPARTITE_MATCHING_H
     3 #define LEMON_MAX_BIPARTITE_MATCHING_H
     4 
     5 /// \ingroup galgs
     6 /// \file
     7 /// \brief Maximum bipartite matchings, b-matchings and 
     8 /// capacitated b-matchings.
     9 ///
    10 /// This file contains a class for bipartite maximum matching, b-matchings 
    11 /// and capacitated b-matching computations.
    12 ///
    13 // /// \author Marton Makai
    14 
    15 //#include <for_each_macros.h>
    16 #include <bipartite_graph_wrapper.h>
    17 //#include <lemon/maps.h>
    18 #include <lemon/max_flow.h>
    19 
    20 namespace lemon {
    21 
    22   // template <typename Graph, typename EdgeCap, typename NodeCap, 
    23   // 	  typename EdgeFlow, typename NodeFlow>
    24   // class MaxMatching : public MaxFlow<stGraphWrapper<Graph>, 
    25   // 				   stGraphWrapper<Graph>:: EdgeMapWrapper<EdgeCan, NodeCap>, stGraphWrapper<Graph>::EdgeMapWrapper<EdgeFlow, NodeFlow> > {
    26   //   typedef MaxFlow<stGraphWrapper<Graph>, 
    27   // 		  stGraphWrapper<Graph>::EdgeMapWrapper<EdgeCan, NodeCap>, 
    28   // 		  stGraphWrapper<Graph>::EdgeMapWrapper<EdgeFlow, NodeFlow> >
    29   //   Parent;
    30   // protected:
    31   //   stGraphWrapper<Graph> gw;
    32   //   stGraphWrapper<Graph>::EdgeMapWrapper<EdgeCap, NodeCap> cap;
    33   //   stGraphWrapper<Graph>::EdgeMapWrapper<EdgeFlow, NodeFlow> flow;
    34   //   //graph* g;
    35   //   //EdgeCap* edge_cap;
    36   //   //EdgeFlow* edge_flow;
    37   // public:
    38   //   MaxMatching(Graph& _g, EdgeCap& _edge_cap, NodeCap& _node_cap, 
    39   // 	      EdgeFlow& _edge_flow, NodeFlow& _node_flow) : 
    40   //     MaxFlow(), gw(_g), 
    41   //     cap(_edge_cap, _node_cap), flow(_edge_flow, _node_flow) {
    42   //     Parent::set(gw, cap, flow);
    43   //   }
    44   // };
    45 
    46   /// \brief A bipartite matching class.
    47   ///
    48   /// This class reduces the matching problem to a flow problem and 
    49   /// a preflow is used on a wrapper. Such a generic approach means that 
    50   /// matchings, b-matchings an capacitated b-matchings can be handled in 
    51   /// a similar way. Due to the efficiency of the preflow algorithm, an 
    52   /// efficient matching framework is obtained.
    53   /// \ingroup galgs
    54   template <typename Graph, typename EdgeCap, typename NodeCap, 
    55 	    typename EdgeFlow, typename NodeFlow>
    56   class MaxBipartiteMatching {
    57   protected:
    58     //   EdgeCap* edge_cap;
    59     //   NodeCap* node_cap;
    60     //   EdgeFlow* edge_flow;
    61     //   NodeFlow* node_flow;
    62     typedef  stBipartiteGraphWrapper<Graph> stGW;
    63     stGW stgw;
    64     typedef typename stGW::template EdgeMapWrapper<EdgeCap, NodeCap> CapMap; 
    65     CapMap cap;
    66     NodeFlow* node_flow;
    67     typedef typename stGW::template EdgeMapWrapper<EdgeFlow, NodeFlow> FlowMap;
    68     FlowMap flow;
    69     typedef MaxFlow<stGW, int, CapMap, FlowMap> MaxFlow;
    70     MaxFlow mf;
    71     //graph* g;
    72     //EdgeCap* edge_cap;
    73     //EdgeFlow* edge_flow;
    74   public:
    75     enum MatchingEnum{
    76       ZERO_MATCHING,
    77       GEN_MATCHING,
    78       GEN_MATCHING_WITH_GOOD_NODE_FLOW,
    79       NO_MATCHING
    80     };
    81     /// For capacitated b-matchings, edge-caoacities and node-capacities 
    82     /// have to be given. After running \c run the matching is is given 
    83     /// back in the edge-map \c _edge_flow and \c _node_map can be used 
    84     /// to obtain saturation information about nodes.
    85     ///\bug Note that the values in _edge_flow and _node_flow have 
    86     /// to form a flow.
    87     MaxBipartiteMatching(Graph& _g, EdgeCap& _edge_cap, NodeCap& _node_cap, 
    88 		EdgeFlow& _edge_flow, NodeFlow& _node_flow) : 
    89       stgw(_g), 
    90       cap(_edge_cap, _node_cap), 
    91       node_flow(0), 
    92       flow(_edge_flow, _node_flow), 
    93       mf(stgw, stgw.S_NODE, stgw.T_NODE, cap, flow) { }
    94     /// If the saturation information of nodes is not needed that the use of 
    95     /// this constructor is more comfortable.
    96     ///\bug Note that the values in _edge_flow and _node_flow have 
    97     /// to form a flow.
    98     MaxBipartiteMatching(Graph& _g, EdgeCap& _edge_cap, NodeCap& _node_cap, 
    99 		EdgeFlow& _edge_flow/*, NodeFlow& _node_flow*/) : 
   100       stgw(_g), 
   101       cap(_edge_cap, _node_cap), 
   102       node_flow(new NodeFlow(_g)), 
   103       flow(_edge_flow, *node_flow), 
   104       mf(stgw, stgw.S_NODE, stgw.T_NODE, cap, flow) { }
   105     /// The class have a nontrivial destructor.
   106     ~MaxBipartiteMatching() { if (node_flow) delete node_flow; }
   107     /// run computes the max matching.
   108     void run(MatchingEnum me=ZERO_MATCHING) { 
   109       switch (me) {
   110 	case ZERO_MATCHING:
   111 	  mf.run(MaxFlow::ZERO_FLOW);
   112 	  break;
   113 	case GEN_MATCHING:
   114 	{
   115 	  typename stGW::OutEdgeIt e;
   116 	  for (stgw.first(e, stgw.S_NODE); stgw.valid(e); stgw.next(e)) 
   117 	    flow.set(e, cap[e]);
   118 	}
   119 	{
   120 	  typename stGW::InEdgeIt e;
   121 	  for (stgw.first(e, stgw.T_NODE); stgw.valid(e); stgw.next(e)) 
   122 	    flow.set(e, 0);
   123 	}
   124 	mf.run(MaxFlow::PRE_FLOW);
   125 	break;
   126 	case GEN_MATCHING_WITH_GOOD_NODE_FLOW:
   127 	  mf.run(MaxFlow::GEN_FLOW);
   128 	  break;
   129 	case NO_MATCHING:
   130 	  mf.run(MaxFlow::NO_FLOW);
   131 	  break;
   132       }
   133     } 
   134     /// The matching value after running \c run.
   135     int matchingValue() const { return mf.flowValue(); }
   136   };
   137 
   138 } //namespace lemon
   139 
   140 #endif //LEMON_MAX_BIPARTITE_MATCHING_H