LEMON/LEMON-main Changeset - r856:5df6a8f29d5e

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Changeset - r856:5df6a8f29d5e

« 854:9a7e4e
« 850:e77b62

857:abb95d »

r856:5df6a8f29d5e

Wed, 03 Mar 2010 18:14:17

[Not Reviewed]

0 comments (0 inline)

alpar (Alpar Juttner)
alpar@cs.elte.hu

Merge #181, #323

0 2 0

merge default

0 files changed with 217 insertions and 95 deletions:

lemon/suurballe.h

214

test/suurballe_test.cc

↑ Collapse diff ↑

lemon/suurballe.h

Show inline comments

@@ -26,12 +26,13 @@
 		#include <vector>
 		#include <limits>
 		#include <lemon/bin_heap.h>
 		#include <lemon/path.h>
 		#include <lemon/list_graph.h>
 		#include <lemon/dijkstra.h>
 		#include <lemon/maps.h>
 		namespace lemon {
 		  /// \addtogroup shortest_path
 		  /// @{
@@ -43,24 +44,24 @@
 		  /// finding arc-disjoint paths having minimum total length (cost)
 		  /// from a given source node to a given target node in a digraph.
 		  ///
 		  /// Note that this problem is a special case of the \ref min_cost_flow
 		  /// "minimum cost flow problem". This implementation is actually an
 		  /// efficient specialized version of the \ref CapacityScaling
-		  /// "Successive Shortest Path" algorithm directly for this problem.
+		  /// "successive shortest path" algorithm directly for this problem.
 		  /// Therefore this class provides query functions for flow values and
 		  /// node potentials (the dual solution) just like the minimum cost flow
 		  /// algorithms.
 		  ///
 		  /// \tparam GR The digraph type the algorithm runs on.
 		  /// \tparam LEN The type of the length map.
 		  /// The default value is <tt>GR::ArcMap<int></tt>.
 		  ///
-		  /// \warning Length values should be \e non-negative \e integers.
 		  /// \warning Length values should be \e non-negative.
 		  ///
 		  /// \note For finding node-disjoint paths this algorithm can be used
+		  /// \note For finding \e node-disjoint paths, this algorithm can be used
 		  /// along with the \ref SplitNodes adaptor.
 		#ifdef DOXYGEN
 		  template <typename GR, typename LEN>
 		#else
 		  template < typename GR,
 		             typename LEN = typename GR::template ArcMap<int> >
@@ -94,121 +95,163 @@
 		    /// The type of the path structures.
 		    typedef SimplePath<GR> Path;
 		  private:
 		    typedef typename Digraph::template NodeMap<int> HeapCrossRef;
 		    typedef BinHeap<Length, HeapCrossRef> Heap;
 		    // ResidualDijkstra is a special implementation of the
 		    // Dijkstra algorithm for finding shortest paths in the
 		    // residual network with respect to the reduced arc lengths
 		    // and modifying the node potentials according to the
 		    // distance of the nodes.
 		    class ResidualDijkstra
+		    {
 		      typedef typename Digraph::template NodeMap<int> HeapCrossRef;
 		      typedef BinHeap<Length, HeapCrossRef> Heap;
 		    private:
 		      // The digraph the algorithm runs on
 		      const Digraph &_graph;
 		      // The main maps
 		      const LengthMap &_length;
 		      const FlowMap &_flow;
 		      const LengthMap &_length;
 		      PotentialMap &_potential;
 		      // The distance map
 		      PotentialMap _dist;
 		      // The pred arc map
 		      PotentialMap &_pi;
 		      PredMap &_pred;
 		      // The processed (i.e. permanently labeled) nodes
 		      std::vector<Node> _proc_nodes;
 		      Node _s;
 		      Node _t;
 		      PotentialMap _dist;
 		      std::vector<Node> _proc_nodes;
 		    public:
 		      /// Constructor.
 		      ResidualDijkstra( const Digraph &graph,
 		                        const FlowMap &flow,
 		                        const LengthMap &length,
 		                        PotentialMap &potential,
 		                        PredMap &pred,
 		                        Node s, Node t ) :
 		        _graph(graph), _flow(flow), _length(length), _potential(potential),
-		        _dist(graph), _pred(pred), _s(s), _t(t) {}
+		      // Constructor
 		      ResidualDijkstra(Suurballe &srb) :
 		        _graph(srb._graph), _length(srb._length),
 		        _flow(*srb._flow), _pi(*srb._potential), _pred(srb._pred),
 		        _s(srb._s), _t(srb._t), _dist(_graph) {}
 		      // Run the algorithm and return true if a path is found
 		      // from the source node to the target node.
 		      bool run(int cnt) {
 		        return cnt == 0 ? startFirst() : start();
+		      }
 		      /// \brief Run the algorithm. It returns \c true if a path is found
 		      /// from the source node to the target node.
-		      bool run() {
+		    private:
 		      // Execute the algorithm for the first time (the flow and potential
 		      // functions have to be identically zero).
 		      bool startFirst() {
 		        HeapCrossRef heap_cross_ref(_graph, Heap::PRE_HEAP);
 		        Heap heap(heap_cross_ref);
 		        heap.push(_s, 0);
 		        _pred[_s] = INVALID;
 		        _proc_nodes.clear();
 		        // Process nodes
 		        while (!heap.empty() && heap.top() != _t) {
 		          Node u = heap.top(), v;
-		          Length d = heap.prio() + _potential[u], nd;
+		          Length d = heap.prio(), dn;
 		          _dist[u] = heap.prio();
 		          _proc_nodes.push_back(u);
 		          heap.pop();
 		          // Traverse outgoing arcs
 		          for (OutArcIt e(_graph, u); e != INVALID; ++e) {
 		            v = _graph.target(e);
 		            switch(heap.state(v)) {
 		              case Heap::PRE_HEAP:
 		                heap.push(v, d + _length[e]);
 		                _pred[v] = e;
 		                break;
 		              case Heap::IN_HEAP:
 		                dn = d + _length[e];
 		                if (dn < heap[v]) {
 		                  heap.decrease(v, dn);
 		                  _pred[v] = e;
+		                }
 		                break;
 		              case Heap::POST_HEAP:
 		                break;
+		            }
+		          }
+		        }
 		        if (heap.empty()) return false;
 		        // Update potentials of processed nodes
 		        Length t_dist = heap.prio();
 		        for (int i = 0; i < int(_proc_nodes.size()); ++i)
 		          _pi[_proc_nodes[i]] = _dist[_proc_nodes[i]] - t_dist;
 		        return true;
+		      }
 		      // Execute the algorithm.
 		      bool start() {
 		        HeapCrossRef heap_cross_ref(_graph, Heap::PRE_HEAP);
 		        Heap heap(heap_cross_ref);
 		        heap.push(_s, 0);
 		        _pred[_s] = INVALID;
 		        _proc_nodes.clear();
 		        // Process nodes
 		        while (!heap.empty() && heap.top() != _t) {
 		          Node u = heap.top(), v;
 		          Length d = heap.prio() + _pi[u], dn;
 		          _dist[u] = heap.prio();
 		          _proc_nodes.push_back(u);
 		          heap.pop();
 		          // Traverse outgoing arcs
 		          for (OutArcIt e(_graph, u); e != INVALID; ++e) {
 		            if (_flow[e] == 0) {
 		              v = _graph.target(e);
 		              switch(heap.state(v)) {
 		              case Heap::PRE_HEAP:
 		                heap.push(v, d + _length[e] - _potential[v]);
 		                _pred[v] = e;
 		                break;
 		              case Heap::IN_HEAP:
 		                nd = d + _length[e] - _potential[v];
 		                if (nd < heap[v]) {
 		                  heap.decrease(v, nd);
 		                case Heap::PRE_HEAP:
 		                  heap.push(v, d + _length[e] - _pi[v]);
 		                  _pred[v] = e;
+		                }
 		                break;
 		              case Heap::POST_HEAP:
 		                break;
 		                  break;
 		                case Heap::IN_HEAP:
 		                  dn = d + _length[e] - _pi[v];
 		                  if (dn < heap[v]) {
 		                    heap.decrease(v, dn);
 		                    _pred[v] = e;
+		                  }
 		                  break;
 		                case Heap::POST_HEAP:
 		                  break;
+		              }
+		            }
+		          }
 		          // Traverse incoming arcs
 		          for (InArcIt e(_graph, u); e != INVALID; ++e) {
 		            if (_flow[e] == 1) {
 		              v = _graph.source(e);
 		              switch(heap.state(v)) {
 		              case Heap::PRE_HEAP:
 		                heap.push(v, d - _length[e] - _potential[v]);
 		                _pred[v] = e;
 		                break;
 		              case Heap::IN_HEAP:
 		                nd = d - _length[e] - _potential[v];
 		                if (nd < heap[v]) {
 		                  heap.decrease(v, nd);
 		                case Heap::PRE_HEAP:
 		                  heap.push(v, d - _length[e] - _pi[v]);
 		                  _pred[v] = e;
+		                }
 		                break;
 		              case Heap::POST_HEAP:
 		                break;
 		                  break;
 		                case Heap::IN_HEAP:
 		                  dn = d - _length[e] - _pi[v];
 		                  if (dn < heap[v]) {
 		                    heap.decrease(v, dn);
 		                    _pred[v] = e;
+		                  }
 		                  break;
 		                case Heap::POST_HEAP:
 		                  break;
+		              }
+		            }
+		          }
+		        }
 		        if (heap.empty()) return false;
 		        // Update potentials of processed nodes
 		        Length t_dist = heap.prio();
 		        for (int i = 0; i < int(_proc_nodes.size()); ++i)
-		          _potential[_proc_nodes[i]] += _dist[_proc_nodes[i]] - t_dist;
+		          _pi[_proc_nodes[i]] += _dist[_proc_nodes[i]] - t_dist;
 		        return true;
+		      }
 		    }; //class ResidualDijkstra
 		  private:
@@ -223,48 +266,49 @@
 		    bool _local_flow;
 		    // Node map of the current potentials
 		    PotentialMap *_potential;
 		    bool _local_potential;
 		    // The source node
-		    Node _source;
+		    Node _s;
 		    // The target node
-		    Node _target;
+		    Node _t;
 		    // Container to store the found paths
-		    std::vector< SimplePath<Digraph> > paths;
+		    std::vector<Path> _paths;
 		    int _path_num;
 		    // The pred arc map
 		    PredMap _pred;
 		    // Implementation of the Dijkstra algorithm for finding augmenting
 		    // shortest paths in the residual network
-		    ResidualDijkstra *_dijkstra;
 		    // Data for full init
 		    PotentialMap *_init_dist;
 		    PredMap *_init_pred;
 		    bool _full_init;
 		  public:
 		    /// \brief Constructor.
 		    ///
 		    /// Constructor.
 		    ///
 		    /// \param graph The digraph the algorithm runs on.
 		    /// \param length The length (cost) values of the arcs.
 		    Suurballe( const Digraph &graph,
 		               const LengthMap &length ) :
 		      _graph(graph), _length(length), _flow(0), _local_flow(false),
 		      _potential(0), _local_potential(false), _pred(graph)
+		    {
 		      LEMON_ASSERT(std::numeric_limits<Length>::is_integer,
 		        "The length type of Suurballe must be integer");
+		    }
+		      _potential(0), _local_potential(false), _pred(graph),
 		      _init_dist(0), _init_pred(0)
 		    {}
 		    /// Destructor.
 		    ~Suurballe() {
 		      if (_local_flow) delete _flow;
 		      if (_local_potential) delete _potential;
-		      delete _dijkstra;
+		      delete _init_dist;
 		      delete _init_pred;
+		    }
 		    /// \brief Set the flow map.
 		    ///
 		    /// This function sets the flow map.
 		    /// If it is not used before calling \ref run() or \ref init(),
@@ -303,16 +347,19 @@
 		      _potential = &map;
 		      return *this;
+		    }
 		    /// \name Execution Control
 		    /// The simplest way to execute the algorithm is to call the run()
 		    /// function.
 		    /// \n
 		    /// function.\n
 		    /// If you need to execute the algorithm many times using the same
 		    /// source node, then you may call fullInit() once and start()
 		    /// for each target node.\n
 		    /// If you only need the flow that is the union of the found
-		    /// arc-disjoint paths, you may call init() and findFlow().
+		    /// arc-disjoint paths, then you may call findFlow() instead of
 		    /// start().
 		    /// @{
 		    /// \brief Run the algorithm.
 		    ///
 		    /// This function runs the algorithm.
@@ -326,41 +373,94 @@
 		    /// arc-disjoint paths found.
 		    ///
 		    /// \note Apart from the return value, <tt>s.run(s, t, k)</tt> is
 		    /// just a shortcut of the following code.
 		    /// \code
 		    ///   s.init(s);
 		    ///   s.findFlow(t, k);
 		    ///   s.findPaths();
 		    ///   s.start(t, k);
 		    /// \endcode
 		    int run(const Node& s, const Node& t, int k = 2) {
 		      init(s);
 		      findFlow(t, k);
 		      findPaths();
 		      start(t, k);
 		      return _path_num;
+		    }
 		    /// \brief Initialize the algorithm.
 		    ///
 		    /// This function initializes the algorithm.
+		    /// This function initializes the algorithm with the given source node.
 		    ///
 		    /// \param s The source node.
 		    void init(const Node& s) {
-		      _source = s;
+		      _s = s;
 		      // Initialize maps
 		      if (!_flow) {
 		        _flow = new FlowMap(_graph);
 		        _local_flow = true;
+		      }
 		      if (!_potential) {
 		        _potential = new PotentialMap(_graph);
 		        _local_potential = true;
+		      }
 		      for (ArcIt e(_graph); e != INVALID; ++e) (*_flow)[e] = 0;
 		      for (NodeIt n(_graph); n != INVALID; ++n) (*_potential)[n] = 0;
 		      _full_init = false;
+		    }
 		    /// \brief Initialize the algorithm and perform Dijkstra.
 		    ///
 		    /// This function initializes the algorithm and performs a full
 		    /// Dijkstra search from the given source node. It makes consecutive
 		    /// executions of \ref start() "start(t, k)" faster, since they
 		    /// have to perform %Dijkstra only k-1 times.
 		    ///
 		    /// This initialization is usually worth using instead of \ref init()
 		    /// if the algorithm is executed many times using the same source node.
 		    ///
 		    /// \param s The source node.
 		    void fullInit(const Node& s) {
 		      // Initialize maps
 		      init(s);
 		      if (!_init_dist) {
 		        _init_dist = new PotentialMap(_graph);
+		      }
 		      if (!_init_pred) {
 		        _init_pred = new PredMap(_graph);
+		      }
 		      // Run a full Dijkstra
 		      typename Dijkstra<Digraph, LengthMap>
 		        ::template SetStandardHeap<Heap>
 		        ::template SetDistMap<PotentialMap>
 		        ::template SetPredMap<PredMap>
 		        ::Create dijk(_graph, _length);
 		      dijk.distMap(*_init_dist).predMap(*_init_pred);
 		      dijk.run(s);
 		      _full_init = true;
+		    }
 		    /// \brief Execute the algorithm.
 		    ///
 		    /// This function executes the algorithm.
 		    ///
 		    /// \param t The target node.
 		    /// \param k The number of paths to be found.
 		    ///
 		    /// \return \c k if there are at least \c k arc-disjoint paths from
 		    /// \c s to \c t in the digraph. Otherwise it returns the number of
 		    /// arc-disjoint paths found.
 		    ///
 		    /// \note Apart from the return value, <tt>s.start(t, k)</tt> is
 		    /// just a shortcut of the following code.
 		    /// \code
 		    ///   s.findFlow(t, k);
 		    ///   s.findPaths();
 		    /// \endcode
 		    int start(const Node& t, int k = 2) {
 		      findFlow(t, k);
 		      findPaths();
 		      return _path_num;
+		    }
 		    /// \brief Execute the algorithm to find an optimal flow.
 		    ///
 		    /// This function executes the successive shortest path algorithm to
 		    /// find a minimum cost flow, which is the union of \c k (or less)
@@ -372,26 +472,45 @@
 		    /// \return \c k if there are at least \c k arc-disjoint paths from
 		    /// the source node to the given node \c t in the digraph.
 		    /// Otherwise it returns the number of arc-disjoint paths found.
 		    ///
 		    /// \pre \ref init() must be called before using this function.
 		    int findFlow(const Node& t, int k = 2) {
 		      _target = t;
 		      _dijkstra =
 		        new ResidualDijkstra( _graph, *_flow, _length, *_potential, _pred,
 		                              _source, _target );
 		      _t = t;
 		      ResidualDijkstra dijkstra(*this);
 		      // Initialization
 		      for (ArcIt e(_graph); e != INVALID; ++e) {
 		        (*_flow)[e] = 0;
+		      }
 		      if (_full_init) {
 		        for (NodeIt n(_graph); n != INVALID; ++n) {
 		          (*_potential)[n] = (*_init_dist)[n];
+		        }
 		        Node u = _t;
 		        Arc e;
 		        while ((e = (*_init_pred)[u]) != INVALID) {
 		          (*_flow)[e] = 1;
 		          u = _graph.source(e);
+		        }
 		        _path_num = 1;
 		      } else {
 		        for (NodeIt n(_graph); n != INVALID; ++n) {
 		          (*_potential)[n] = 0;
+		        }
 		        _path_num = 0;
+		      }
 		      // Find shortest paths
 		      _path_num = 0;
 		      while (_path_num < k) {
 		        // Run Dijkstra
-		        if (!_dijkstra->run()) break;
+		        if (!dijkstra.run(_path_num)) break;
 		        ++_path_num;
 		        // Set the flow along the found shortest path
-		        Node u = _target;
+		        Node u = _t;
 		        Arc e;
 		        while ((e = _pred[u]) != INVALID) {
 		          if (u == _graph.target(e)) {
 		            (*_flow)[e] = 1;
 		            u = _graph.source(e);
 		          } else {
@@ -402,30 +521,30 @@
+		      }
 		      return _path_num;
+		    }
 		    /// \brief Compute the paths from the flow.
 		    ///
 		    /// This function computes the paths from the found minimum cost flow,
 		    /// which is the union of some arc-disjoint paths.
 		    /// This function computes arc-disjoint paths from the found minimum
 		    /// cost flow, which is the union of them.
 		    ///
 		    /// \pre \ref init() and \ref findFlow() must be called before using
 		    /// this function.
 		    void findPaths() {
 		      FlowMap res_flow(_graph);
 		      for(ArcIt a(_graph); a != INVALID; ++a) res_flow[a] = (*_flow)[a];
 		      paths.clear();
 		      paths.resize(_path_num);
 		      _paths.clear();
 		      _paths.resize(_path_num);
 		      for (int i = 0; i < _path_num; ++i) {
 		        Node n = _source;
 		        while (n != _target) {
 		        Node n = _s;
 		        while (n != _t) {
 		          OutArcIt e(_graph, n);
 		          for ( ; res_flow[e] == 0; ++e) ;
 		          n = _graph.target(e);
-		          paths[i].addBack(e);
+		          _paths[i].addBack(e);
 		          res_flow[e] = 0;
+		        }
+		      }
+		    }
 		    /// @}
@@ -517,14 +636,14 @@
 		    ///
 		    /// \param i The function returns the <tt>i</tt>-th path.
 		    /// \c i must be between \c 0 and <tt>%pathNum()-1</tt>.
 		    ///
 		    /// \pre \ref run() or \ref findPaths() must be called before using
 		    /// this function.
 		    Path path(int i) const {
 		      return paths[i];
 		    const Path& path(int i) const {
 		      return _paths[i];
+		    }
 		    /// @}
 		  }; //class Suurballe

test/suurballe_test.cc

Show inline comments

@@ -98,12 +98,15 @@
 		    .potentialMap(pi);
 		  int k;
 		  k = suurb_test.run(n, n);
 		  k = suurb_test.run(n, n, k);
 		  suurb_test.init(n);
 		  suurb_test.fullInit(n);
 		  suurb_test.start(n);
 		  suurb_test.start(n, k);
 		  k = suurb_test.findFlow(n);
 		  k = suurb_test.findFlow(n, k);
 		  suurb_test.findPaths();
 		  int f;
 		  VType c;

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