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Changeset 605:5232721b3f14 in lemon-1.2 for lemon

Timestamp:

03/25/09 15:58:44 (16 years ago)

Author:

Peter Kovacs <kpeter@…>

Branch:

default

Phase:

public

Message:

Rework the interface of NetworkSimplex? (#234)

The parameters of the problem can be set with separate functions
instead of different constructors.

File:

: 1 edited

lemon/network_simplex.h (modified) (45 diffs)

Legend:

: Unmodified
: Added
: Removed

lemon/network_simplex.h

-                      r604
+                      r605
 ///
 /// \file
 /// \brief Network simplex algorithm for finding a minimum cost flow.
+/// \brief Network Simplex algorithm for finding a minimum cost flow.
 #include <vector>
 …
   /// @{
   /// \brief Implementation of the primal network simplex algorithm
+  /// \brief Implementation of the primal Network Simplex algorithm
   /// for finding a \ref min_cost_flow "minimum cost flow".
   ///
   /// \ref NetworkSimplex implements the primal network simplex algorithm
+  /// \ref NetworkSimplex implements the primal Network Simplex algorithm
   /// for finding a \ref min_cost_flow "minimum cost flow".
   ///
+  /// \tparam Digraph The digraph type the algorithm runs on.
+  /// \tparam LowerMap The type of the lower bound map.
+  /// \tparam CapacityMap The type of the capacity (upper bound) map.
+  /// \tparam CostMap The type of the cost (length) map.
+  /// \tparam SupplyMap The type of the supply map.
+  /// \tparam GR The digraph type the algorithm runs on.
+  /// \tparam V The value type used in the algorithm.
+  /// By default it is \c int.
   ///
+  /// \warning
+  /// - Arc capacities and costs should be \e non-negative \e integers.
+  /// - Supply values should be \e signed \e integers.
+  /// - The value types of the maps should be convertible to each other.
+  /// - \c CostMap::Value must be signed type.
+  /// \warning \c V must be a signed integer type.
   ///
+  /// \note \ref NetworkSimplex provides five different pivot rule
+  /// implementations that significantly affect the efficiency of the
+  /// algorithm.
+  /// By default "Block Search" pivot rule is used, which proved to be
+  /// by far the most efficient according to our benchmark tests.
+  /// However another pivot rule can be selected using \ref run()
+  /// function with the proper parameter.
+#ifdef DOXYGEN
+  template < typename Digraph,
+             typename LowerMap,
+             typename CapacityMap,
+             typename CostMap,
+             typename SupplyMap >
+#else
+  template < typename Digraph,
+             typename LowerMap = typename Digraph::template ArcMap<int>,
+             typename CapacityMap = typename Digraph::template ArcMap<int>,
+             typename CostMap = typename Digraph::template ArcMap<int>,
+             typename SupplyMap = typename Digraph::template NodeMap<int> >
+#endif
+  /// \note %NetworkSimplex provides five different pivot rule
+  /// implementations. For more information see \ref PivotRule.
+  template <typename GR, typename V = int>
   class NetworkSimplex
+  {
+    TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
+    typedef typename CapacityMap::Value Capacity;
+    typedef typename CostMap::Value Cost;
+    typedef typename SupplyMap::Value Supply;
+  public:
+    /// The value type of the algorithm
+    typedef V Value;
+    /// The type of the flow map
+    typedef typename GR::template ArcMap<Value> FlowMap;
+    /// The type of the potential map
+    typedef typename GR::template NodeMap<Value> PotentialMap;
+  public:
+    /// \brief Enum type for selecting the pivot rule.
+    ///
+    /// Enum type for selecting the pivot rule for the \ref run()
+    /// function.
+    ///
+    /// \ref NetworkSimplex provides five different pivot rule
+    /// implementations that significantly affect the running time
+    /// of the algorithm.
+    /// By default \ref BLOCK_SEARCH "Block Search" is used, which
+    /// proved to be the most efficient and the most robust on various
+    /// test inputs according to our benchmark tests.
+    /// However another pivot rule can be selected using the \ref run()
+    /// function with the proper parameter.
+    enum PivotRule {
+      /// The First Eligible pivot rule.
+      /// The next eligible arc is selected in a wraparound fashion
+      /// in every iteration.
+      FIRST_ELIGIBLE,
+      /// The Best Eligible pivot rule.
+      /// The best eligible arc is selected in every iteration.
+      BEST_ELIGIBLE,
+      /// The Block Search pivot rule.
+      /// A specified number of arcs are examined in every iteration
+      /// in a wraparound fashion and the best eligible arc is selected
+      /// from this block.
+      BLOCK_SEARCH,
+      /// The Candidate List pivot rule.
+      /// In a major iteration a candidate list is built from eligible arcs
+      /// in a wraparound fashion and in the following minor iterations
+      /// the best eligible arc is selected from this list.
+      CANDIDATE_LIST,
+      /// The Altering Candidate List pivot rule.
+      /// It is a modified version of the Candidate List method.
+      /// It keeps only the several best eligible arcs from the former
+      /// candidate list and extends this list in every iteration.
+      ALTERING_LIST
+    };
+  private:
+    TEMPLATE_DIGRAPH_TYPEDEFS(GR);
+    typedef typename GR::template ArcMap<Value> ValueArcMap;
+    typedef typename GR::template NodeMap<Value> ValueNodeMap;
     typedef std::vector<Arc> ArcVector;
 …
     typedef std::vector<int> IntVector;
     typedef std::vector<bool> BoolVector;
+    typedef std::vector<Capacity> CapacityVector;
+    typedef std::vector<Cost> CostVector;
+    typedef std::vector<Supply> SupplyVector;
+  public:
+    /// The type of the flow map
+    typedef typename Digraph::template ArcMap<Capacity> FlowMap;
+    /// The type of the potential map
+    typedef typename Digraph::template NodeMap<Cost> PotentialMap;
+  public:
+    /// Enum type for selecting the pivot rule used by \ref run()
+    enum PivotRuleEnum {
+      FIRST_ELIGIBLE_PIVOT,
+      BEST_ELIGIBLE_PIVOT,
+      BLOCK_SEARCH_PIVOT,
+      CANDIDATE_LIST_PIVOT,
+      ALTERING_LIST_PIVOT
+    };
+  private:
+    typedef std::vector<Value> ValueVector;
     // State constants for arcs
 …
   private:
+    // References for the original data
+    const Digraph &_graph;
+    const LowerMap *_orig_lower;
+    const CapacityMap &_orig_cap;
+    const CostMap &_orig_cost;
+    const SupplyMap *_orig_supply;
+    Node _orig_source;
+    Node _orig_target;
+    Capacity _orig_flow_value;
+    // Data related to the underlying digraph
+    const GR &_graph;
+    int _node_num;
+    int _arc_num;
+    // Parameters of the problem
+    ValueArcMap *_plower;
+    ValueArcMap *_pupper;
+    ValueArcMap *_pcost;
+    ValueNodeMap *_psupply;
+    bool _pstsup;
+    Node _psource, _ptarget;
+    Value _pstflow;
     // Result maps
 …
     bool _local_potential;
+    // The number of nodes and arcs in the original graph
+    int _node_num;
+    int _arc_num;
+    // Data structures for storing the graph
+    // Data structures for storing the digraph
     IntNodeMap _node_id;
     ArcVector _arc_ref;
 …
     IntVector _target;
     // Node and arc maps
     CapacityVector _cap;
     CostVector _cost;
     CostVector _supply;
     CapacityVector _flow;
     CostVector _pi;
+    // Node and arc data
+    ValueVector _cap;
+    ValueVector _cost;
+    ValueVector _supply;
+    ValueVector _flow;
+    ValueVector _pi;
     // Data for storing the spanning tree structure
 …
     int first, second, right, last;
     int stem, par_stem, new_stem;
     Capacity delta;
+    Value delta;
   private:
+    /// \brief Implementation of the "First Eligible" pivot rule for the
+    /// \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// This class implements the "First Eligible" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// For more information see \ref NetworkSimplex::run().
+    // Implementation of the First Eligible pivot rule
     class FirstEligiblePivotRule
+    {
 …
       const IntVector  &_source;
       const IntVector  &_target;
       const CostVector &_cost;
+      const ValueVector &_cost;
       const IntVector  &_state;
       const CostVector &_pi;
+      const ValueVector &_pi;
       int &_in_arc;
       int _arc_num;
 …
     public:
       /// Constructor
+      // Constructor
       FirstEligiblePivotRule(NetworkSimplex &ns) :
         _source(ns._source), _target(ns._target),
 …
       {}
       /// Find next entering arc
+      // Find next entering arc
       bool findEnteringArc() {
         Cost c;
+        Value c;
         for (int e = _next_arc; e < _arc_num; ++e) {
           c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]);
 …
+    /// \brief Implementation of the "Best Eligible" pivot rule for the
+    /// \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// This class implements the "Best Eligible" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// For more information see \ref NetworkSimplex::run().
+    // Implementation of the Best Eligible pivot rule
     class BestEligiblePivotRule
+    {
 …
       const IntVector  &_source;
       const IntVector  &_target;
       const CostVector &_cost;
+      const ValueVector &_cost;
       const IntVector  &_state;
       const CostVector &_pi;
+      const ValueVector &_pi;
       int &_in_arc;
       int _arc_num;
 …
     public:
       /// Constructor
+      // Constructor
       BestEligiblePivotRule(NetworkSimplex &ns) :
         _source(ns._source), _target(ns._target),
 …
       {}
       /// Find next entering arc
+      // Find next entering arc
       bool findEnteringArc() {
         Cost c, min = 0;
+        Value c, min = 0;
         for (int e = 0; e < _arc_num; ++e) {
           c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]);
 …
+    /// \brief Implementation of the "Block Search" pivot rule for the
+    /// \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// This class implements the "Block Search" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// For more information see \ref NetworkSimplex::run().
+    // Implementation of the Block Search pivot rule
     class BlockSearchPivotRule
+    {
 …
       const IntVector  &_source;
       const IntVector  &_target;
       const CostVector &_cost;
+      const ValueVector &_cost;
       const IntVector  &_state;
       const CostVector &_pi;
+      const ValueVector &_pi;
       int &_in_arc;
       int _arc_num;
 …
     public:
       /// Constructor
+      // Constructor
       BlockSearchPivotRule(NetworkSimplex &ns) :
         _source(ns._source), _target(ns._target),
 …
+      }
       /// Find next entering arc
+      // Find next entering arc
       bool findEnteringArc() {
         Cost c, min = 0;
+        Value c, min = 0;
         int cnt = _block_size;
         int e, min_arc = _next_arc;
 …
+    /// \brief Implementation of the "Candidate List" pivot rule for the
+    /// \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// This class implements the "Candidate List" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// For more information see \ref NetworkSimplex::run().
+    // Implementation of the Candidate List pivot rule
     class CandidateListPivotRule
+    {
 …
       const IntVector  &_source;
       const IntVector  &_target;
       const CostVector &_cost;
+      const ValueVector &_cost;
       const IntVector  &_state;
       const CostVector &_pi;
+      const ValueVector &_pi;
       int &_in_arc;
       int _arc_num;
 …
       /// Find next entering arc
       bool findEnteringArc() {
         Cost min, c;
+        Value min, c;
         int e, min_arc = _next_arc;
         if (_curr_length > 0 && _minor_count < _minor_limit) {
 …
+    /// \brief Implementation of the "Altering Candidate List" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// This class implements the "Altering Candidate List" pivot rule
+    /// for the \ref NetworkSimplex "network simplex" algorithm.
+    ///
+    /// For more information see \ref NetworkSimplex::run().
+    // Implementation of the Altering Candidate List pivot rule
     class AlteringListPivotRule
+    {
 …
       const IntVector  &_source;
       const IntVector  &_target;
       const CostVector &_cost;
+      const ValueVector &_cost;
       const IntVector  &_state;
       const CostVector &_pi;
+      const ValueVector &_pi;
       int &_in_arc;
       int _arc_num;
 …
       int _next_arc;
       IntVector _candidates;
       CostVector _cand_cost;
+      ValueVector _cand_cost;
       // Functor class to compare arcs during sort of the candidate list
 …
+      {
       private:
         const CostVector &_map;
+        const ValueVector &_map;
       public:
         SortFunc(const CostVector &map) : _map(map) {}
+        SortFunc(const ValueVector &map) : _map(map) {}
         bool operator()(int left, int right) {
           return _map[left] > _map[right];
 …
     public:
       /// Constructor
+      // Constructor
       AlteringListPivotRule(NetworkSimplex &ns) :
         _source(ns._source), _target(ns._target),
 …
+      }
       /// Find next entering arc
+      // Find next entering arc
       bool findEnteringArc() {
         // Check the current candidate list
 …
   public:
     /// \brief General constructor (with lower bounds).
     ///
     /// General constructor (with lower bounds).
+    /// \brief Constructor.
+    ///
+    /// Constructor.
     ///
     /// \param graph The digraph the algorithm runs on.
+    /// \param lower The lower bounds of the arcs.
+    /// \param capacity The capacities (upper bounds) of the arcs.
+    /// \param cost The cost (length) values of the arcs.
+    /// \param supply The supply values of the nodes (signed).
+    NetworkSimplex( const Digraph &graph,
+                    const LowerMap &lower,
+                    const CapacityMap &capacity,
+                    const CostMap &cost,
+                    const SupplyMap &supply ) :
+      _graph(graph), _orig_lower(&lower), _orig_cap(capacity),
+      _orig_cost(cost), _orig_supply(&supply),
+    NetworkSimplex(const GR& graph) :
+      _graph(graph),
+      _plower(NULL), _pupper(NULL), _pcost(NULL),
+      _psupply(NULL), _pstsup(false),
       _flow_map(NULL), _potential_map(NULL),
       _local_flow(false), _local_potential(false),
       _node_id(graph)
+    {}
+    /// \brief General constructor (without lower bounds).
+    ///
+    /// General constructor (without lower bounds).
+    ///
+    /// \param graph The digraph the algorithm runs on.
+    /// \param capacity The capacities (upper bounds) of the arcs.
+    /// \param cost The cost (length) values of the arcs.
+    /// \param supply The supply values of the nodes (signed).
+    NetworkSimplex( const Digraph &graph,
+                    const CapacityMap &capacity,
+                    const CostMap &cost,
+                    const SupplyMap &supply ) :
+      _graph(graph), _orig_lower(NULL), _orig_cap(capacity),
+      _orig_cost(cost), _orig_supply(&supply),
+      _flow_map(NULL), _potential_map(NULL),
+      _local_flow(false), _local_potential(false),
+      _node_id(graph)
+    {}
+    /// \brief Simple constructor (with lower bounds).
+    ///
+    /// Simple constructor (with lower bounds).
+    ///
+    /// \param graph The digraph the algorithm runs on.
+    /// \param lower The lower bounds of the arcs.
+    /// \param capacity The capacities (upper bounds) of the arcs.
+    /// \param cost The cost (length) values of the arcs.
+    /// \param s The source node.
+    /// \param t The target node.
+    /// \param flow_value The required amount of flow from node \c s
+    /// to node \c t (i.e. the supply of \c s and the demand of \c t).
+    NetworkSimplex( const Digraph &graph,
+                    const LowerMap &lower,
+                    const CapacityMap &capacity,
+                    const CostMap &cost,
+                    Node s, Node t,
+                    Capacity flow_value ) :
+      _graph(graph), _orig_lower(&lower), _orig_cap(capacity),
+      _orig_cost(cost), _orig_supply(NULL),
+      _orig_source(s), _orig_target(t), _orig_flow_value(flow_value),
+      _flow_map(NULL), _potential_map(NULL),
+      _local_flow(false), _local_potential(false),
+      _node_id(graph)
+    {}
+    /// \brief Simple constructor (without lower bounds).
+    ///
+    /// Simple constructor (without lower bounds).
+    ///
+    /// \param graph The digraph the algorithm runs on.
+    /// \param capacity The capacities (upper bounds) of the arcs.
+    /// \param cost The cost (length) values of the arcs.
+    /// \param s The source node.
+    /// \param t The target node.
+    /// \param flow_value The required amount of flow from node \c s
+    /// to node \c t (i.e. the supply of \c s and the demand of \c t).
+    NetworkSimplex( const Digraph &graph,
+                    const CapacityMap &capacity,
+                    const CostMap &cost,
+                    Node s, Node t,
+                    Capacity flow_value ) :
+      _graph(graph), _orig_lower(NULL), _orig_cap(capacity),
+      _orig_cost(cost), _orig_supply(NULL),
+      _orig_source(s), _orig_target(t), _orig_flow_value(flow_value),
+      _flow_map(NULL), _potential_map(NULL),
+      _local_flow(false), _local_potential(false),
+      _node_id(graph)
+    {}
+    {
+      LEMON_ASSERT(std::numeric_limits<Value>::is_integer &&
+                   std::numeric_limits<Value>::is_signed,
+        "The value type of NetworkSimplex must be a signed integer");
+    }
     /// Destructor.
 …
+    }
+    /// \brief Set the lower bounds on the arcs.
+    ///
+    /// This function sets the lower bounds on the arcs.
+    /// If neither this function nor \ref boundMaps() is used before
+    /// calling \ref run(), the lower bounds will be set to zero
+    /// on all arcs.
+    ///
+    /// \param map An arc map storing the lower bounds.
+    /// Its \c Value type must be convertible to the \c Value type
+    /// of the algorithm.
+    ///
+    /// \return <tt>(*this)</tt>
+    template <typename LOWER>
+    NetworkSimplex& lowerMap(const LOWER& map) {
+      delete _plower;
+      _plower = new ValueArcMap(_graph);
+      for (ArcIt a(_graph); a != INVALID; ++a) {
+        (*_plower)[a] = map[a];
+      }
+      return *this;
+    }
+    /// \brief Set the upper bounds (capacities) on the arcs.
+    ///
+    /// This function sets the upper bounds (capacities) on the arcs.
+    /// If none of the functions \ref upperMap(), \ref capacityMap()
+    /// and \ref boundMaps() is used before calling \ref run(),
+    /// the upper bounds (capacities) will be set to
+    /// \c std::numeric_limits<Value>::max() on all arcs.
+    ///
+    /// \param map An arc map storing the upper bounds.
+    /// Its \c Value type must be convertible to the \c Value type
+    /// of the algorithm.
+    ///
+    /// \return <tt>(*this)</tt>
+    template<typename UPPER>
+    NetworkSimplex& upperMap(const UPPER& map) {
+      delete _pupper;
+      _pupper = new ValueArcMap(_graph);
+      for (ArcIt a(_graph); a != INVALID; ++a) {
+        (*_pupper)[a] = map[a];
+      }
+      return *this;
+    }
+    /// \brief Set the upper bounds (capacities) on the arcs.
+    ///
+    /// This function sets the upper bounds (capacities) on the arcs.
+    /// It is just an alias for \ref upperMap().
+    ///
+    /// \return <tt>(*this)</tt>
+    template<typename CAP>
+    NetworkSimplex& capacityMap(const CAP& map) {
+      return upperMap(map);
+    }
+    /// \brief Set the lower and upper bounds on the arcs.
+    ///
+    /// This function sets the lower and upper bounds on the arcs.
+    /// If neither this function nor \ref lowerMap() is used before
+    /// calling \ref run(), the lower bounds will be set to zero
+    /// on all arcs.
+    /// If none of the functions \ref upperMap(), \ref capacityMap()
+    /// and \ref boundMaps() is used before calling \ref run(),
+    /// the upper bounds (capacities) will be set to
+    /// \c std::numeric_limits<Value>::max() on all arcs.
+    ///
+    /// \param lower An arc map storing the lower bounds.
+    /// \param upper An arc map storing the upper bounds.
+    ///
+    /// The \c Value type of the maps must be convertible to the
+    /// \c Value type of the algorithm.
+    ///
+    /// \note This function is just a shortcut of calling \ref lowerMap()
+    /// and \ref upperMap() separately.
+    ///
+    /// \return <tt>(*this)</tt>
+    template <typename LOWER, typename UPPER>
+    NetworkSimplex& boundMaps(const LOWER& lower, const UPPER& upper) {
+      return lowerMap(lower).upperMap(upper);
+    }
+    /// \brief Set the costs of the arcs.
+    ///
+    /// This function sets the costs of the arcs.
+    /// If it is not used before calling \ref run(), the costs
+    /// will be set to \c 1 on all arcs.
+    ///
+    /// \param map An arc map storing the costs.
+    /// Its \c Value type must be convertible to the \c Value type
+    /// of the algorithm.
+    ///
+    /// \return <tt>(*this)</tt>
+    template<typename COST>
+    NetworkSimplex& costMap(const COST& map) {
+      delete _pcost;
+      _pcost = new ValueArcMap(_graph);
+      for (ArcIt a(_graph); a != INVALID; ++a) {
+        (*_pcost)[a] = map[a];
+      }
+      return *this;
+    }
+    /// \brief Set the supply values of the nodes.
+    ///
+    /// This function sets the supply values of the nodes.
+    /// If neither this function nor \ref stSupply() is used before
+    /// calling \ref run(), the supply of each node will be set to zero.
+    /// (It makes sense only if non-zero lower bounds are given.)
+    ///
+    /// \param map A node map storing the supply values.
+    /// Its \c Value type must be convertible to the \c Value type
+    /// of the algorithm.
+    ///
+    /// \return <tt>(*this)</tt>
+    template<typename SUP>
+    NetworkSimplex& supplyMap(const SUP& map) {
+      delete _psupply;
+      _pstsup = false;
+      _psupply = new ValueNodeMap(_graph);
+      for (NodeIt n(_graph); n != INVALID; ++n) {
+        (*_psupply)[n] = map[n];
+      }
+      return *this;
+    }
+    /// \brief Set single source and target nodes and a supply value.
+    ///
+    /// This function sets a single source node and a single target node
+    /// and the required flow value.
+    /// If neither this function nor \ref supplyMap() is used before
+    /// calling \ref run(), the supply of each node will be set to zero.
+    /// (It makes sense only if non-zero lower bounds are given.)
+    ///
+    /// \param s The source node.
+    /// \param t The target node.
+    /// \param k The required amount of flow from node \c s to node \c t
+    /// (i.e. the supply of \c s and the demand of \c t).
+    ///
+    /// \return <tt>(*this)</tt>
+    NetworkSimplex& stSupply(const Node& s, const Node& t, Value k) {
+      delete _psupply;
+      _psupply = NULL;
+      _pstsup = true;
+      _psource = s;
+      _ptarget = t;
+      _pstflow = k;
+      return *this;
+    }
     /// \brief Set the flow map.
     ///
     /// This function sets the flow map.
+    /// If it is not used before calling \ref run(), an instance will
+    /// be allocated automatically. The destructor deallocates this
+    /// automatically allocated map, of course.
     ///
     /// \return <tt>(*this)</tt>
     NetworkSimplex& flowMap(FlowMap &map) {
+    NetworkSimplex& flowMap(FlowMap& map) {
       if (_local_flow) {
         delete _flow_map;
 …
     /// \brief Set the potential map.
     ///
+    /// This function sets the potential map.
+    /// This function sets the potential map, which is used for storing
+    /// the dual solution.
+    /// If it is not used before calling \ref run(), an instance will
+    /// be allocated automatically. The destructor deallocates this
+    /// automatically allocated map, of course.
     ///
     /// \return <tt>(*this)</tt>
     NetworkSimplex& potentialMap(PotentialMap &map) {
+    NetworkSimplex& potentialMap(PotentialMap& map) {
       if (_local_potential) {
         delete _potential_map;
 …
+    }
     /// \name Execution control
     /// The algorithm can be executed using the
+    /// \ref lemon::NetworkSimplex::run() "run()" function.
+    /// \name Execution Control
+    /// The algorithm can be executed using \ref run().
     /// @{
 …
     ///
     /// This function runs the algorithm.
+    ///
+    /// \param pivot_rule The pivot rule that is used during the
+    /// algorithm.
+    ///
+    /// The available pivot rules:
+    ///
+    /// - FIRST_ELIGIBLE_PIVOT The next eligible arc is selected in
+    /// a wraparound fashion in every iteration
+    /// (\ref FirstEligiblePivotRule).
+    ///
+    /// - BEST_ELIGIBLE_PIVOT The best eligible arc is selected in
+    /// every iteration (\ref BestEligiblePivotRule).
+    ///
+    /// - BLOCK_SEARCH_PIVOT A specified number of arcs are examined in
+    /// every iteration in a wraparound fashion and the best eligible
+    /// arc is selected from this block (\ref BlockSearchPivotRule).
+    ///
+    /// - CANDIDATE_LIST_PIVOT In a major iteration a candidate list is
+    /// built from eligible arcs in a wraparound fashion and in the
+    /// following minor iterations the best eligible arc is selected
+    /// from this list (\ref CandidateListPivotRule).
+    ///
+    /// - ALTERING_LIST_PIVOT It is a modified version of the
+    /// "Candidate List" pivot rule. It keeps only the several best
+    /// eligible arcs from the former candidate list and extends this
+    /// list in every iteration (\ref AlteringListPivotRule).
+    ///
+    /// According to our comprehensive benchmark tests the "Block Search"
+    /// pivot rule proved to be the fastest and the most robust on
+    /// various test inputs. Thus it is the default option.
+    /// The paramters can be specified using \ref lowerMap(),
+    /// \ref upperMap(), \ref capacityMap(), \ref boundMaps(),
+    /// \ref costMap(), \ref supplyMap() and \ref stSupply()
+    /// functions. For example,
+    /// \code
+    ///   NetworkSimplex<ListDigraph> ns(graph);
+    ///   ns.boundMaps(lower, upper).costMap(cost)
+    ///     .supplyMap(sup).run();
+    /// \endcode
+    ///
+    /// \param pivot_rule The pivot rule that will be used during the
+    /// algorithm. For more information see \ref PivotRule.
     ///
     /// \return \c true if a feasible flow can be found.
     bool run(PivotRuleEnum pivot_rule = BLOCK_SEARCH_PIVOT) {
+    bool run(PivotRule pivot_rule = BLOCK_SEARCH) {
       return init() && start(pivot_rule);
+    }
 …
     /// The results of the algorithm can be obtained using these
     /// functions.\n
     /// \ref lemon::NetworkSimplex::run() "run()" must be called before
+    /// using them.
+    /// The \ref run() function must be called before using them.
     /// @{
+    /// \brief Return the total cost of the found flow.
+    ///
+    /// This function returns the total cost of the found flow.
+    /// The complexity of the function is \f$ O(e) \f$.
+    ///
+    /// \note The return type of the function can be specified as a
+    /// template parameter. For example,
+    /// \code
+    ///   ns.totalCost<double>();
+    /// \endcode
+    /// It is useful if the total cost cannot be stored in the \c Value
+    /// type of the algorithm, which is the default return type of the
+    /// function.
+    ///
+    /// \pre \ref run() must be called before using this function.
+    template <typename Num>
+    Num totalCost() const {
+      Num c = 0;
+      if (_pcost) {
+        for (ArcIt e(_graph); e != INVALID; ++e)
+          c += (*_flow_map)[e] * (*_pcost)[e];
+      } else {
+        for (ArcIt e(_graph); e != INVALID; ++e)
+          c += (*_flow_map)[e];
+      }
+      return c;
+    }
+#ifndef DOXYGEN
+    Value totalCost() const {
+      return totalCost<Value>();
+    }
+#endif
+    /// \brief Return the flow on the given arc.
+    ///
+    /// This function returns the flow on the given arc.
+    ///
+    /// \pre \ref run() must be called before using this function.
+    Value flow(const Arc& a) const {
+      return (*_flow_map)[a];
+    }
     /// \brief Return a const reference to the flow map.
 …
+    }
+    /// \brief Return the potential (dual value) of the given node.
+    ///
+    /// This function returns the potential (dual value) of the
+    /// given node.
+    ///
+    /// \pre \ref run() must be called before using this function.
+    Value potential(const Node& n) const {
+      return (*_potential_map)[n];
+    }
     /// \brief Return a const reference to the potential map
     /// (the dual solution).
     ///
     /// This function returns a const reference to a node map storing
+    /// the found potentials (the dual solution).
+    /// the found potentials, which form the dual solution of the
+    /// \ref min_cost_flow "minimum cost flow" problem.
     ///
     /// \pre \ref run() must be called before using this function.
     const PotentialMap& potentialMap() const {
       return *_potential_map;
+    }
-    /// \brief Return the flow on the given arc.
-    ///
-    /// This function returns the flow on the given arc.
-    ///
-    /// \pre \ref run() must be called before using this function.
-    Capacity flow(const Arc& arc) const {
-      return (*_flow_map)[arc];
+    }
-    /// \brief Return the potential of the given node.
-    ///
-    /// This function returns the potential of the given node.
-    ///
-    /// \pre \ref run() must be called before using this function.
-    Cost potential(const Node& node) const {
-      return (*_potential_map)[node];
+    }
-    /// \brief Return the total cost of the found flow.
-    ///
-    /// This function returns the total cost of the found flow.
-    /// The complexity of the function is \f$ O(e) \f$.
-    ///
-    /// \pre \ref run() must be called before using this function.
-    Cost totalCost() const {
-      Cost c = 0;
-      for (ArcIt e(_graph); e != INVALID; ++e)
-        c += (*_flow_map)[e] * _orig_cost[e];
-      return c;
+    }
 …
       int all_node_num = _node_num + 1;
       int all_arc_num = _arc_num + _node_num;
+      if (_node_num == 0) return false;
       _arc_ref.resize(_arc_num);
 …
       // Initialize node related data
       bool valid_supply = true;
+      if (_orig_supply) {
+        Supply sum = 0;
+      if (!_pstsup && !_psupply) {
+        _pstsup = true;
+        _psource = _ptarget = NodeIt(_graph);
+        _pstflow = 0;
+      }
+      if (_psupply) {
+        Value sum = 0;
         int i = 0;
         for (NodeIt n(_graph); n != INVALID; ++n, ++i) {
           _node_id[n] = i;
           _supply[i] = (*_orig_supply)[n];
+          _supply[i] = (*_psupply)[n];
           sum += _supply[i];
+        }
 …
           _supply[i] = 0;
+        }
         _supply[_node_id[_orig_source]] =  _orig_flow_value;
         _supply[_node_id[_orig_target]] = -_orig_flow_value;
+        _supply[_node_id[_psource]] =  _pstflow;
+        _supply[_node_id[_ptarget]]   = -_pstflow;
+      }
       if (!valid_supply) return false;
 …
       // Initialize arc maps
+      for (int i = 0; i != _arc_num; ++i) {
+        Arc e = _arc_ref[i];
+        _source[i] = _node_id[_graph.source(e)];
+        _target[i] = _node_id[_graph.target(e)];
+        _cost[i] = _orig_cost[e];
+        _cap[i] = _orig_cap[e];
+      if (_pupper && _pcost) {
+        for (int i = 0; i != _arc_num; ++i) {
+          Arc e = _arc_ref[i];
+          _source[i] = _node_id[_graph.source(e)];
+          _target[i] = _node_id[_graph.target(e)];
+          _cap[i] = (*_pupper)[e];
+          _cost[i] = (*_pcost)[e];
+        }
+      } else {
+        for (int i = 0; i != _arc_num; ++i) {
+          Arc e = _arc_ref[i];
+          _source[i] = _node_id[_graph.source(e)];
+          _target[i] = _node_id[_graph.target(e)];
+        }
+        if (_pupper) {
+          for (int i = 0; i != _arc_num; ++i)
+            _cap[i] = (*_pupper)[_arc_ref[i]];
+        } else {
+          Value val = std::numeric_limits<Value>::max();
+          for (int i = 0; i != _arc_num; ++i)
+            _cap[i] = val;
+        }
+        if (_pcost) {
+          for (int i = 0; i != _arc_num; ++i)
+            _cost[i] = (*_pcost)[_arc_ref[i]];
+        } else {
+          for (int i = 0; i != _arc_num; ++i)
+            _cost[i] = 1;
+        }
+      }
       // Remove non-zero lower bounds
       if (_orig_lower) {
+      if (_plower) {
         for (int i = 0; i != _arc_num; ++i) {
           Capacity c = (*_orig_lower)[_arc_ref[i]];
+          Value c = (*_plower)[_arc_ref[i]];
           if (c != 0) {
             _cap[i] -= c;
 …
       // Add artificial arcs and initialize the spanning tree data structure
       Cost max_cost = std::numeric_limits<Cost>::max() / 4;
       Capacity max_cap = std::numeric_limits<Capacity>::max();
+      Value max_cap = std::numeric_limits<Value>::max();
+      Value max_cost = std::numeric_limits<Value>::max() / 4;
       for (int u = 0, e = _arc_num; u != _node_num; ++u, ++e) {
         _thread[u] = u + 1;
 …
       delta = _cap[in_arc];
       int result = 0;
       Capacity d;
+      Value d;
       int e;
 …
       // Augment along the cycle
       if (delta > 0) {
         Capacity val = _state[in_arc] * delta;
+        Value val = _state[in_arc] * delta;
         _flow[in_arc] += val;
         for (int u = _source[in_arc]; u != join; u = _parent[u]) {
 …
     // Update potentials
     void updatePotential() {
       Cost sigma = _forward[u_in] ?
+      Value sigma = _forward[u_in] ?
         _pi[v_in] - _pi[u_in] - _cost[_pred[u_in]] :
         _pi[v_in] - _pi[u_in] + _cost[_pred[u_in]];
 …
     // Execute the algorithm
     bool start(PivotRuleEnum pivot_rule) {
+    bool start(PivotRule pivot_rule) {
       // Select the pivot rule implementation
       switch (pivot_rule) {
         case FIRST_ELIGIBLE_PIVOT:
+        case FIRST_ELIGIBLE:
           return start<FirstEligiblePivotRule>();
         case BEST_ELIGIBLE_PIVOT:
+        case BEST_ELIGIBLE:
           return start<BestEligiblePivotRule>();
         case BLOCK_SEARCH_PIVOT:
+        case BLOCK_SEARCH:
           return start<BlockSearchPivotRule>();
         case CANDIDATE_LIST_PIVOT:
+        case CANDIDATE_LIST:
           return start<CandidateListPivotRule>();
         case ALTERING_LIST_PIVOT:
+        case ALTERING_LIST:
           return start<AlteringListPivotRule>();
+      }
 …
+    }
     template<class PivotRuleImplementation>
+    template <typename PivotRuleImpl>
     bool start() {
       PivotRuleImplementation pivot(*this);
       // Execute the network simplex algorithm
+      PivotRuleImpl pivot(*this);
+      // Execute the Network Simplex algorithm
       while (pivot.findEnteringArc()) {
         findJoinNode();
 …
       // Copy flow values to _flow_map
       if (_orig_lower) {
+      if (_plower) {
         for (int i = 0; i != _arc_num; ++i) {
           Arc e = _arc_ref[i];
           _flow_map->set(e, (*_orig_lower)[e] + _flow[i]);
+          _flow_map->set(e, (*_plower)[e] + _flow[i]);
+        }
       } else {

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Changeset 605:5232721b3f14 in lemon-1.2 for lemon

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lemon/network_simplex.h

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