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kpeter (Peter Kovacs)
kpeter@inf.elte.hu
Add a parameter to control arc mixing in NS (#298)
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1 file changed with 24 insertions and 9 deletions:
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Ignore white space 48 line context
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@@ -604,98 +604,113 @@
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      search_end:
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        // Make heap of the candidate list (approximating a partial sort)
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        make_heap( _candidates.begin(), _candidates.begin() + _curr_length,
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                   _sort_func );
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        // Pop the first element of the heap
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        _in_arc = _candidates[0];
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        _next_arc = e;
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        pop_heap( _candidates.begin(), _candidates.begin() + _curr_length,
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                  _sort_func );
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        _curr_length = std::min(_head_length, _curr_length - 1);
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        return true;
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      }
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    }; //class AlteringListPivotRule
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  public:
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    /// \brief Constructor.
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    ///
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    /// The constructor of the class.
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    ///
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    /// \param graph The digraph the algorithm runs on.
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    NetworkSimplex(const GR& graph) :
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    /// \param arc_mixing Indicate if the arcs have to be stored in a
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    /// mixed order in the internal data structure. 
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    /// In special cases, it could lead to better overall performance,
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    /// but it is usually slower. Therefore it is disabled by default.
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    NetworkSimplex(const GR& graph, bool arc_mixing = false) :
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      _graph(graph), _node_id(graph), _arc_id(graph),
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      INF(std::numeric_limits<Value>::has_infinity ?
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          std::numeric_limits<Value>::infinity() :
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          std::numeric_limits<Value>::max())
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    {
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      // Check the value types
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      LEMON_ASSERT(std::numeric_limits<Value>::is_signed,
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        "The flow type of NetworkSimplex must be signed");
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      LEMON_ASSERT(std::numeric_limits<Cost>::is_signed,
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        "The cost type of NetworkSimplex must be signed");
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      // Resize vectors
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      _node_num = countNodes(_graph);
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      _arc_num = countArcs(_graph);
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      int all_node_num = _node_num + 1;
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      int max_arc_num = _arc_num + 2 * _node_num;
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      _source.resize(max_arc_num);
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      _target.resize(max_arc_num);
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      _lower.resize(_arc_num);
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      _upper.resize(_arc_num);
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      _cap.resize(max_arc_num);
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      _cost.resize(max_arc_num);
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      _supply.resize(all_node_num);
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      _flow.resize(max_arc_num);
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      _pi.resize(all_node_num);
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      _parent.resize(all_node_num);
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      _pred.resize(all_node_num);
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      _forward.resize(all_node_num);
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      _thread.resize(all_node_num);
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      _rev_thread.resize(all_node_num);
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      _succ_num.resize(all_node_num);
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      _last_succ.resize(all_node_num);
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      _state.resize(max_arc_num);
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      // Copy the graph (store the arcs in a mixed order)
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      // Copy the graph
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      int i = 0;
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      for (NodeIt n(_graph); n != INVALID; ++n, ++i) {
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        _node_id[n] = i;
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      }
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      int k = std::max(int(std::sqrt(double(_arc_num))), 10);
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      i = 0;
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      for (ArcIt a(_graph); a != INVALID; ++a) {
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        _arc_id[a] = i;
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        _source[i] = _node_id[_graph.source(a)];
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        _target[i] = _node_id[_graph.target(a)];
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        if ((i += k) >= _arc_num) i = (i % k) + 1;
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      if (arc_mixing) {
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        // Store the arcs in a mixed order
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        int k = std::max(int(std::sqrt(double(_arc_num))), 10);
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        int i = 0, j = 0;
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        for (ArcIt a(_graph); a != INVALID; ++a) {
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          _arc_id[a] = i;
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          _source[i] = _node_id[_graph.source(a)];
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          _target[i] = _node_id[_graph.target(a)];
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          if ((i += k) >= _arc_num) i = ++j;
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        }
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      } else {
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        // Store the arcs in the original order
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        int i = 0;
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        for (ArcIt a(_graph); a != INVALID; ++a, ++i) {
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          _arc_id[a] = i;
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          _source[i] = _node_id[_graph.source(a)];
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          _target[i] = _node_id[_graph.target(a)];
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        }
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      }
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      // Initialize maps
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      for (int i = 0; i != _node_num; ++i) {
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        _supply[i] = 0;
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      }
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      for (int i = 0; i != _arc_num; ++i) {
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        _lower[i] = 0;
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        _upper[i] = INF;
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        _cost[i] = 1;
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      }
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      _have_lower = false;
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      _stype = GEQ;
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    }
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    /// \name Parameters
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    /// The parameters of the algorithm can be specified using these
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    /// functions.
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    /// @{
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    /// \brief Set the lower bounds on the arcs.
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    ///
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    /// This function sets the lower bounds on the arcs.
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