Changeset - r896:fb932bcfd803
« 895:dca9ee
903:3ffd46 »
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kpeter (Peter Kovacs)
kpeter@inf.elte.hu
Improve arc mixing in NS and enable it by default (#391)
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1 file changed with 7 insertions and 6 deletions:
lemon/network_simplex.h
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lemon/network_simplex.h
Ignore white space 12 line context
... ... 
@@ -633,17 +633,18 @@
633 633 

			




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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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    /// \param arc_mixing Indicate if the arcs have to be stored in a


			




	
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    /// \param arc_mixing Indicate if the arcs will 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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    /// In general, it leads to similar performance as using the original


			




	
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    /// arc order, but it makes the algorithm more robust and in special


			




	
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    /// cases, even significantly faster. Therefore, it is enabled by default.


			




	
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    NetworkSimplex(const GR& graph, bool arc_mixing = true) :


			




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      _graph(graph), _node_id(graph), _arc_id(graph),


			




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      _arc_mixing(arc_mixing),


			




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      MAX(std::numeric_limits<Value>::max()),


			




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      INF(std::numeric_limits<Value>::has_infinity ?


			




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          std::numeric_limits<Value>::infinity() : MAX)


			




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    {


			




	...
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@@ -927,19 +928,19 @@


			




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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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      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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        const int skip = std::max(_arc_num / _node_num, 3);


			




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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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          if ((i += skip) >= _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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