RhodeCode

      return reached(t);

    }

    /// \brief Runs the algorithm to visit all nodes in the digraph.

    ///

    /// This method runs the %BFS algorithm in order to

    /// compute the shortest path to each node.

    ///

    /// The algorithm computes

    /// - the shortest path tree (forest),

    /// - the distance of each node from the root(s).

    ///

    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.

    ///\code

    ///  b.init();

    ///  for (NodeIt n(gr); n != INVALID; ++n) {

    ///    if (!b.reached(n)) {

    ///      b.addSource(n);

    ///      b.start();

    ///    }

    ///  }

    ///\endcode

    void run() {

      init();

      for (NodeIt it(*_digraph); it != INVALID; ++it) {

        if (!reached(it)) {

          addSource(it);

          start();

        }

      }

    }

    ///@}

    /// \name Query Functions

    /// The results of the BFS algorithm can be obtained using these

    /// functions.\n

    /// Either \ref run(Node) "run()" or \ref start() should be called

    /// before using them.

    ///@{

    /// \brief Checks if a node is reached from the root(s).

    ///

    /// Returns \c true if \c v is reached from the root(s).

    ///

    /// \pre Either \ref run(Node) "run()" or \ref init()

    /// must be called before using this function.

    ///@}

  };

} //END OF NAMESPACE LEMON

#endif

    /// Sets the lower bound map for the supply of the nodes.

    /// \return <tt>(*this)</tt>

    Circulation& deltaMap(const DeltaMap& map) {

      _delta = ↦

      return *this;

    }

    /// \brief Sets the flow map.

    ///

    /// Sets the flow map.

    /// If you don't use this function before calling \ref run() or

    /// \ref init(), an instance will be allocated automatically.

    /// The destructor deallocates this automatically allocated map,

    /// of course.

    /// \return <tt>(*this)</tt>

    Circulation& flowMap(FlowMap& map) {

      if (_local_flow) {

        delete _flow;

        _local_flow = false;

      }

      _flow = ↦

      return *this;

    }

    /// \brief Sets the elevator used by algorithm.

    ///

    /// Sets the elevator used by algorithm.

    /// If you don't use this function before calling \ref run() or

    /// \ref init(), an instance will be allocated automatically.

    /// The destructor deallocates this automatically allocated elevator,

    /// of course.

    /// \return <tt>(*this)</tt>

    Circulation& elevator(Elevator& elevator) {

      if (_local_level) {

        delete _level;

        _local_level = false;

      }

      _level = &elevator;

      return *this;

    }

    /// \brief Returns a const reference to the elevator.

    ///

    /// Returns a const reference to the elevator.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

      return *_level;

    }

    /// \brief Sets the tolerance used by algorithm.

    ///

    /// Sets the tolerance used by algorithm.

    Circulation& tolerance(const Tolerance& tolerance) const {

      _tol = tolerance;

      return *this;

    }

    /// \brief Returns a const reference to the tolerance.

    ///

    /// Returns a const reference to the tolerance.

    const Tolerance& tolerance() const {

      return tolerance;

    }

    /// \name Execution Control

    /// The simplest way to execute the algorithm is to call \ref run().\n

    /// If you need more control on the initial solution or the execution,

    /// first you have to call one of the \ref init() functions, then

    /// the \ref start() function.

    ///@{

    /// Initializes the internal data structures.

    /// Initializes the internal data structures and sets all flow values

    /// to the lower bound.

    void init()

    {

      createStructures();

      for(NodeIt n(_g);n!=INVALID;++n) {

        _excess->set(n, (*_delta)[n]);

      }

      for (ArcIt e(_g);e!=INVALID;++e) {

        _flow->set(e, (*_lo)[e]);

        _excess->set(_g.target(e), (*_excess)[_g.target(e)] + (*_flow)[e]);

        _excess->set(_g.source(e), (*_excess)[_g.source(e)] - (*_flow)[e]);

      }

      // global relabeling tested, but in general case it provides

      // worse performance for random digraphs

      _level->initStart();

      for(NodeIt n(_g);n!=INVALID;++n)

        ;

      }

      return true;

    }

    /// Runs the algorithm.

    /// This function runs the algorithm.

    ///

    /// \return \c true if a feasible circulation is found.

    ///

    /// \note Apart from the return value, c.run() is just a shortcut of

    /// the following code.

    /// \code

    ///   c.greedyInit();

    ///   c.start();

    /// \endcode

    bool run() {

      greedyInit();

      return start();

    }

    /// @}

    /// \name Query Functions

    /// The results of the circulation algorithm can be obtained using

    /// these functions.\n

    /// Either \ref run() or \ref start() should be called before

    /// using them.

    ///@{

    /// \brief Returns the flow on the given arc.

    ///

    /// Returns the flow on the given arc.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    Value flow(const Arc& arc) const {

      return (*_flow)[arc];

    }

    /// \brief Returns a const reference to the flow map.

    ///

    /// Returns a const reference to the arc map storing the found flow.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

      return *_flow;

    }

    /**

       \brief Returns \c true if the given node is in a barrier.

       Barrier is a set \e B of nodes for which

       \f[ \sum_{a\in\delta_{out}(B)} upper(a) -

           \sum_{a\in\delta_{in}(B)} lower(a) < \sum_{v\in B}delta(v) \f]

       holds. The existence of a set with this property prooves that a

       feasible circualtion cannot exist.

       This function returns \c true if the given node is in the found

       barrier. If a feasible circulation is found, the function

       gives back \c false for every node.

       \pre Either \ref run() or \ref init() must be called before

       using this function.

       \sa barrierMap()

       \sa checkBarrier()

    */

    {

      return (*_level)[node] >= _el;

    }

    /// \brief Gives back a barrier.

    ///

    /// This function sets \c bar to the characteristic vector of the

    /// found barrier. \c bar should be a \ref concepts::WriteMap "writable"

    /// node map with \c bool (or convertible) value type.

    ///

    /// If a feasible circulation is found, the function gives back an

    /// empty set, so \c bar[v] will be \c false for all nodes \c v.

    ///

    /// \note This function calls \ref barrier() for each node,

    /// so it runs in \f$O(n)\f$ time.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    ///

    /// \sa barrier()

    /// \sa checkBarrier()

    template<class BarrierMap>

    {

      for(NodeIt n(_g);n!=INVALID;++n)

        bar.set(n, (*_level)[n] >= _el);

    }

    /// @}

    /// \name Checker Functions

    /// The feasibility of the results can be checked using

    /// these functions.\n

    /// Either \ref run() or \ref start() should be called before

    /// using them.

    ///@{

    ///Check if the found flow is a feasible circulation

    ///Check if the found flow is a feasible circulation,

    ///

      for(ArcIt e(_g);e!=INVALID;++e)

        if((*_flow)[e]<(*_lo)[e]||(*_flow)[e]>(*_up)[e]) return false;

      for(NodeIt n(_g);n!=INVALID;++n)

        {

          Value dif=-(*_delta)[n];

          for(InArcIt e(_g,n);e!=INVALID;++e) dif-=(*_flow)[e];

          for(OutArcIt e(_g,n);e!=INVALID;++e) dif+=(*_flow)[e];

          if(_tol.negative(dif)) return false;

        }

      return true;

    }

    ///Check whether or not the last execution provides a barrier

    ///Check whether or not the last execution provides a barrier.

    ///\sa barrier()

    ///\sa barrierMap()

    {

      Value delta=0;

      for(NodeIt n(_g);n!=INVALID;++n)

        if(barrier(n))

          delta-=(*_delta)[n];

      for(ArcIt e(_g);e!=INVALID;++e)

        {

          Node s=_g.source(e);

          Node t=_g.target(e);

          if(barrier(s)&&!barrier(t)) delta+=(*_up)[e];

          else if(barrier(t)&&!barrier(s)) delta-=(*_lo)[e];

        }

      return _tol.negative(delta);

    }

    /// @}

  };

}

#endif

      return reached(t);

    }

    /// \brief Runs the algorithm to visit all nodes in the digraph.

    /// This method runs the %DFS algorithm in order to

    /// compute the %DFS path to each node.

    ///

    /// The algorithm computes

    /// - the %DFS tree (forest),

    /// - the distance of each node from the root(s) in the %DFS tree.

    ///

    /// \note <tt>d.run()</tt> is just a shortcut of the following code.

    ///\code

    ///   d.init();

    ///   for (NodeIt n(digraph); n != INVALID; ++n) {

    ///     if (!d.reached(n)) {

    ///       d.addSource(n);

    ///       d.start();

    ///     }

    ///   }

    ///\endcode

    void run() {

      init();

      for (NodeIt it(*_digraph); it != INVALID; ++it) {

        if (!reached(it)) {

          addSource(it);

          start();

        }

      }

    }

    ///@}

    /// \name Query Functions

    /// The results of the DFS algorithm can be obtained using these

    /// functions.\n

    /// Either \ref run(Node) "run()" or \ref start() should be called

    /// before using them.

    ///@{

    /// \brief Checks if a node is reached from the root(s).

    ///

    /// Returns \c true if \c v is reached from the root(s).

    ///

    /// \pre Either \ref run(Node) "run()" or \ref init()

    /// must be called before using this function.

    ///@}

  };

} //END OF NAMESPACE LEMON

#endif

        delete _flow;

        _local_flow = false;

      }

      _flow = ↦

      return *this;

    }

    /// \brief Sets the source node.

    ///

    /// Sets the source node.

    /// \return <tt>(*this)</tt>

    Preflow& source(const Node& node) {

      _source = node;

      return *this;

    }

    /// \brief Sets the target node.

    ///

    /// Sets the target node.

    /// \return <tt>(*this)</tt>

    Preflow& target(const Node& node) {

      _target = node;

      return *this;

    }

    /// \brief Sets the elevator used by algorithm.

    ///

    /// Sets the elevator used by algorithm.

    /// If you don't use this function before calling \ref run() or

    /// \ref init(), an instance will be allocated automatically.

    /// The destructor deallocates this automatically allocated elevator,

    /// of course.

    /// \return <tt>(*this)</tt>

    Preflow& elevator(Elevator& elevator) {

      if (_local_level) {

        delete _level;

        _local_level = false;

      }

      _level = &elevator;

      return *this;

    }

    /// \brief Returns a const reference to the elevator.

    ///

    /// Returns a const reference to the elevator.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

      return *_level;

    }

    /// \brief Sets the tolerance used by algorithm.

    ///

    /// Sets the tolerance used by algorithm.

    Preflow& tolerance(const Tolerance& tolerance) const {

      _tolerance = tolerance;

      return *this;

    }

    /// \brief Returns a const reference to the tolerance.

    ///

    /// Returns a const reference to the tolerance.

    const Tolerance& tolerance() const {

      return tolerance;

    }

    /// \name Execution Control

    /// The simplest way to execute the preflow algorithm is to use

    /// \ref run() or \ref runMinCut().\n

    /// If you need more control on the initial solution or the execution,

    /// first you have to call one of the \ref init() functions, then

    /// \ref startFirstPhase() and if you need it \ref startSecondPhase().

    ///@{

    /// \brief Initializes the internal data structures.

    ///

    /// Initializes the internal data structures and sets the initial

    /// flow to zero on each arc.

    void init() {

      createStructures();

      _phase = true;

      for (NodeIt n(_graph); n != INVALID; ++n) {

        _excess->set(n, 0);

      }

      for (ArcIt e(_graph); e != INVALID; ++e) {

        _flow->set(e, 0);

      }

      typename Digraph::template NodeMap<bool> reached(_graph, false);

      _level->initStart();

      _level->initAddItem(_target);

    ///   pf.startFirstPhase();

    /// \endcode

    void runMinCut() {

      init();

      startFirstPhase();

    }

    /// @}

    /// \name Query Functions

    /// The results of the preflow algorithm can be obtained using these

    /// functions.\n

    /// Either one of the \ref run() "run*()" functions or one of the

    /// \ref startFirstPhase() "start*()" functions should be called

    /// before using them.

    ///@{

    /// \brief Returns the value of the maximum flow.

    ///

    /// Returns the value of the maximum flow by returning the excess

    /// of the target node. This value equals to the value of

    /// the maximum flow already after the first phase of the algorithm.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    Value flowValue() const {

      return (*_excess)[_target];

    }

    /// \brief Returns the flow on the given arc.

    ///

    /// Returns the flow on the given arc. This method can

    /// be called after the second phase of the algorithm.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    Value flow(const Arc& arc) const {

      return (*_flow)[arc];

    }

    /// \brief Returns a const reference to the flow map.

    ///

    /// Returns a const reference to the arc map storing the found flow.

    /// This method can be called after the second phase of the algorithm.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

      return *_flow;

    }

    /// \brief Returns \c true when the node is on the source side of the

    /// minimum cut.

    ///

    /// Returns true when the node is on the source side of the found

    /// minimum cut. This method can be called both after running \ref

    /// startFirstPhase() and \ref startSecondPhase().

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    bool minCut(const Node& node) const {

      return ((*_level)[node] == _level->maxLevel()) == _phase;

    }

    /// \brief Gives back a minimum value cut.

    ///

    /// Sets \c cutMap to the characteristic vector of a minimum value

    /// cut. \c cutMap should be a \ref concepts::WriteMap "writable"

    /// node map with \c bool (or convertible) value type.

    ///

    /// This method can be called both after running \ref startFirstPhase()

    /// and \ref startSecondPhase(). The result after the second phase

    /// could be slightly different if inexact computation is used.

    ///

    /// \note This function calls \ref minCut() for each node, so it runs in

    /// \f$O(n)\f$ time.

    ///

    /// \pre Either \ref run() or \ref init() must be called before

    /// using this function.

    template <typename CutMap>

    void minCutMap(CutMap& cutMap) const {

      for (NodeIt n(_graph); n != INVALID; ++n) {

        cutMap.set(n, minCut(n));

      }

    }

    /// @}

  };

}

#endif