lemon/min_cost_flow.h
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     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2008
     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_MIN_COST_FLOW_H
    20 #define LEMON_MIN_COST_FLOW_H
    21 
    22 /// \ingroup min_cost_flow
    23 ///
    24 /// \file
    25 /// \brief An efficient algorithm for finding a minimum cost flow.
    26 
    27 #include <lemon/network_simplex.h>
    28 
    29 namespace lemon {
    30 
    31   /// \addtogroup min_cost_flow
    32   /// @{
    33 
    34   /// \brief An efficient algorithm for finding a minimum cost flow.
    35   ///
    36   /// \ref MinCostFlow provides an efficient algorithm for finding
    37   /// a minimum cost flow.
    38   ///
    39   /// This class is just an alias for \ref NetworkSimplex,
    40   /// which is the most efficient algorithm for the minimum cost
    41   /// flow problem in LEMON according to our benchmark tests.
    42   /// For the detailed documentation of this class see
    43   /// \ref NetworkSimplex.
    44   ///
    45   /// There are four implementations for the minimum cost flow problem,
    46   /// which can be used exactly the same way.
    47   /// - \ref CapacityScaling
    48   /// - \ref CostScaling
    49   /// - \ref CycleCanceling
    50   /// - \ref NetworkSimplex
    51   ///
    52   /// \tparam Graph The directed graph type the algorithm runs on.
    53   /// \tparam LowerMap The type of the lower bound map.
    54   /// \tparam CapacityMap The type of the capacity (upper bound) map.
    55   /// \tparam CostMap The type of the cost (length) map.
    56   /// \tparam SupplyMap The type of the supply map.
    57   ///
    58   /// \warning
    59   /// - Edge capacities and costs should be \e non-negative \e integers.
    60   /// - Supply values should be \e signed \e integers.
    61   /// - The value types of the maps should be convertible to each other.
    62   /// - \c CostMap::Value must be signed type.
    63   ///
    64   /// \author Peter Kovacs
    65   template < typename Graph,
    66              typename LowerMap = typename Graph::template EdgeMap<int>,
    67              typename CapacityMap = typename Graph::template EdgeMap<int>,
    68              typename CostMap = typename Graph::template EdgeMap<int>,
    69              typename SupplyMap = typename Graph::template NodeMap<int> >
    70   class MinCostFlow :
    71     public NetworkSimplex< Graph, LowerMap, CapacityMap,
    72                            CostMap, SupplyMap >
    73   {
    74     typedef NetworkSimplex< Graph, LowerMap, CapacityMap,
    75                             CostMap, SupplyMap > MinCostFlowImpl;
    76     typedef typename Graph::Node Node;
    77     typedef typename SupplyMap::Value Supply;
    78 
    79   public:
    80 
    81     /// General constructor (with lower bounds).
    82     MinCostFlow( const Graph &graph,
    83                  const LowerMap &lower,
    84                  const CapacityMap &capacity,
    85                  const CostMap &cost,
    86                  const SupplyMap &supply ) :
    87       MinCostFlowImpl(graph, lower, capacity, cost, supply) {}
    88 
    89     /// General constructor of the class (without lower bounds).
    90     MinCostFlow( const Graph &graph,
    91                  const CapacityMap &capacity,
    92                  const CostMap &cost,
    93                  const SupplyMap &supply ) :
    94       MinCostFlowImpl(graph, capacity, cost, supply) {}
    95 
    96     /// Simple constructor (with lower bounds).
    97     MinCostFlow( const Graph &graph,
    98                  const LowerMap &lower,
    99                  const CapacityMap &capacity,
   100                  const CostMap &cost,
   101                  Node s, Node t,
   102                  Supply flow_value ) :
   103       MinCostFlowImpl( graph, lower, capacity, cost,
   104                        s, t, flow_value ) {}
   105 
   106     /// Simple constructor (without lower bounds).
   107     MinCostFlow( const Graph &graph,
   108                  const CapacityMap &capacity,
   109                  const CostMap &cost,
   110                  Node s, Node t,
   111                  Supply flow_value ) :
   112       MinCostFlowImpl( graph, capacity, cost,
   113                        s, t, flow_value ) {}
   114 
   115   }; //class MinCostFlow
   116 
   117   ///@}
   118 
   119 } //namespace lemon
   120 
   121 #endif //LEMON_MIN_COST_FLOW_H