RhodeCode

  /// \e "highest label" and the \e "bound decrease" heuristics.

  /// The worst case time complexity of the algorithm is \f$O(n^2\sqrt{e})\f$.

  ///

  /// The algorithm consists from two phases. After the first phase

  /// the maximal flow value and the minimum cut can be obtained. The

  /// second phase constructs the feasible maximum flow on each arc.

  ///

  /// \param _Graph The digraph type the algorithm runs on.

  /// \param _CapacityMap The flow map type.

  /// \param _Traits Traits class to set various data types used by

  /// the algorithm.  The default traits class is \ref

  /// PreflowDefaultTraits.  See \ref PreflowDefaultTraits for the

  /// documentation of a %Preflow traits class.

  ///

  ///\author Jacint Szabo and Balazs Dezso

#ifdef DOXYGEN

  template <typename _Graph, typename _CapacityMap, typename _Traits>

#else

  template <typename _Graph,

            typename _CapacityMap = typename _Graph::template ArcMap<int>,

            typename _Traits = PreflowDefaultTraits<_Graph, _CapacityMap> >

#endif

  class Preflow {

  public:

    typedef _Traits Traits;

    typedef typename Traits::Digraph Digraph;

    typedef typename Traits::CapacityMap CapacityMap;

    typedef typename Traits::Value Value;

    typedef typename Traits::FlowMap FlowMap;

    typedef typename Traits::Elevator Elevator;

    typedef typename Traits::Tolerance Tolerance;

  private:

    TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

    const Digraph& _graph;

    const CapacityMap* _capacity;

    int _node_num;

    Node _source, _target;

    FlowMap* _flow;

    bool _local_flow;

    Elevator* _level;

    bool _local_level;

    typedef typename Digraph::template NodeMap<Value> ExcessMap;

    ExcessMap* _excess;

    Tolerance _tolerance;

    bool _phase;

    void createStructures() {

      _node_num = countNodes(_graph);

      if (!_flow) {

        _flow = Traits::createFlowMap(_graph);

        _local_flow = true;

      }

      if (!_level) {

        _level = Traits::createElevator(_graph, _node_num);

        _local_level = true;

      }

      if (!_excess) {

        _excess = new ExcessMap(_graph);

      }

    }

    void destroyStructures() {

      if (_local_flow) {

        delete _flow;

      }

      if (_local_level) {

        delete _level;

      }

      if (_excess) {

        delete _excess;

      }

    }

  public:

    typedef Preflow Create;

    ///\name Named template parameters

    ///@{

    template <typename _FlowMap>

      typedef _FlowMap FlowMap;

      static FlowMap *createFlowMap(const Digraph&) {

        LEMON_ASSERT(false, "FlowMap is not initialized");

        return 0; // ignore warnings

      }

    };

    /// \brief \ref named-templ-param "Named parameter" for setting

    /// FlowMap type

    ///

    /// \ref named-templ-param "Named parameter" for setting FlowMap

    /// type

    template <typename _FlowMap>

      typedef Preflow<Digraph, CapacityMap,

    };

    template <typename _Elevator>

      typedef _Elevator Elevator;

      static Elevator *createElevator(const Digraph&, int) {

        LEMON_ASSERT(false, "Elevator is not initialized");

        return 0; // ignore warnings

      }

    };

    /// \brief \ref named-templ-param "Named parameter" for setting

    /// Elevator type

    ///

    /// \ref named-templ-param "Named parameter" for setting Elevator

    /// type

    template <typename _Elevator>

      typedef Preflow<Digraph, CapacityMap,

    };

    template <typename _Elevator>

      typedef _Elevator Elevator;

      static Elevator *createElevator(const Digraph& digraph, int max_level) {

        return new Elevator(digraph, max_level);

      }

    };

    /// \brief \ref named-templ-param "Named parameter" for setting

    /// Elevator type

    ///

    /// \ref named-templ-param "Named parameter" for setting Elevator

    /// type. The Elevator should be standard constructor interface, ie.

    /// the digraph and the maximum level should be passed to it.

    template <typename _Elevator>

      : public Preflow<Digraph, CapacityMap,

      typedef Preflow<Digraph, CapacityMap,

    };

    /// @}

  protected:

    Preflow() {}

  public:

    /// \brief The constructor of the class.

    ///

    /// The constructor of the class.

    /// \param digraph The digraph the algorithm runs on.

    /// \param capacity The capacity of the arcs.

    /// \param source The source node.

    /// \param target The target node.

    Preflow(const Digraph& digraph, const CapacityMap& capacity,

               Node source, Node target)

      : _graph(digraph), _capacity(&capacity),

        _node_num(0), _source(source), _target(target),

        _flow(0), _local_flow(false),

        _level(0), _local_level(false),

        _excess(0), _tolerance(), _phase() {}

    /// \brief Destrcutor.

    ///

    /// Destructor.

    ~Preflow() {

      destroyStructures();

    }

    /// \brief Sets the capacity map.

    ///

    /// Sets the capacity map.

    /// \return \c (*this)

    Preflow& capacityMap(const CapacityMap& map) {

      _capacity = ↦

      return *this;

    }

    /// \brief Sets the flow map.

    ///

    /// Sets the flow map.

    /// \return \c (*this)

    Preflow& flowMap(FlowMap& map) {

      if (_local_flow) {

        delete _flow;

        _local_flow = false;

      }

      _flow = ↦

      return *this;

    }

    /// \brief Returns the flow map.

    ///

    /// \return The flow map.

    const FlowMap& flowMap() {

      return *_flow;

    }

    /// \brief Sets the elevator.

    ///

    /// Sets the elevator.

    /// \return \c (*this)

    Preflow& elevator(Elevator& elevator) {

      if (_local_level) {

        delete _level;

        _local_level = false;

      }

      _level = &elevator;

      return *this;

    }

    /// \brief Returns the elevator.

    ///

    /// \return The elevator.

    const Elevator& elevator() {

      return *_level;

    }

    /// \brief Sets the source node.

    ///

    /// Sets the source node.

    /// \return \c (*this)

    Preflow& source(const Node& node) {

      _source = node;

      return *this;

    }

    /// \brief Sets the target node.

    ///

    /// Sets the target node.

    /// \return \c (*this)

    Preflow& target(const Node& node) {

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2008

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#include <fstream>

#include <string>

#include "test_tools.h"

#include <lemon/smart_graph.h>

#include <lemon/preflow.h>

#include <lemon/concepts/digraph.h>

#include <lemon/concepts/maps.h>

#include <lemon/lgf_reader.h>

using namespace lemon;

void checkPreflow()

{

  typedef int VType;

  typedef concepts::Digraph Digraph;

  typedef Digraph::Node Node;

  typedef Digraph::Arc Arc;

  typedef concepts::ReadMap<Arc,VType> CapMap;

  typedef concepts::ReadWriteMap<Arc,VType> FlowMap;

  typedef concepts::WriteMap<Node,bool> CutMap;

  Digraph g;

  Node n;

  Arc e;

  CapMap cap;

  FlowMap flow;

  CutMap cut;

  preflow_test.capacityMap(cap);

  flow = preflow_test.flowMap();

  preflow_test.flowMap(flow);

  preflow_test.source(n);

  preflow_test.target(n);

  preflow_test.init();

  preflow_test.flowInit(cap);

  preflow_test.startFirstPhase();

  preflow_test.startSecondPhase();

  preflow_test.run();

  preflow_test.runMinCut();

  preflow_test.flowValue();

  preflow_test.minCut(n);

  preflow_test.minCutMap(cut);

  preflow_test.flow(e);

}

int cutValue (const SmartDigraph& g,

              const SmartDigraph::NodeMap<bool>& cut,

              const SmartDigraph::ArcMap<int>& cap) {

  int c=0;

  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {

    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];

  }

  return c;

}

bool checkFlow(const SmartDigraph& g,

               const SmartDigraph::ArcMap<int>& flow,

               const SmartDigraph::ArcMap<int>& cap,

               SmartDigraph::Node s, SmartDigraph::Node t) {

  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {

    if (flow[e] < 0 || flow[e] > cap[e]) return false;

  }

  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {

    if (n == s || n == t) continue;

    int sum = 0;

    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {

      sum += flow[e];

    }

    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {

      sum -= flow[e];

    }

    if (sum != 0) return false;

  }

  return true;

}

int main() {

  typedef SmartDigraph Digraph;

  typedef Digraph::Node Node;

  typedef Digraph::NodeIt NodeIt;

  typedef Digraph::ArcIt ArcIt;

  typedef Digraph::ArcMap<int> CapMap;

  typedef Digraph::ArcMap<int> FlowMap;

  typedef Digraph::NodeMap<bool> CutMap;

  typedef Preflow<Digraph, CapMap> PType;

  std::string f_name;

  if( getenv("srcdir") )

    f_name = std::string(getenv("srcdir"));

  else f_name = ".";

  f_name += "/test/preflow_graph.lgf";

  std::ifstream file(f_name.c_str());

  check(file, "Input file '" << f_name << "' not found.");

  Digraph g;

  Node s, t;

  CapMap cap(g);

  DigraphReader<Digraph>(g,file).

    arcMap("capacity", cap).

    node("source",s).

    node("target",t).

    run();

  PType preflow_test(g, cap, s, t);

  preflow_test.run();

  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),

        "The flow is not feasible.");

  CutMap min_cut(g);

  preflow_test.minCutMap(min_cut);

  int min_cut_value=cutValue(g,min_cut,cap);