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1 // -*- C++ -*- |
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2 #ifndef HUGO_TIGHT_EDGE_FILTER_MAP_H |
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3 #define HUGO_TIGHT_EDGE_FILTER_MAP_H |
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4 |
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5 // /// \file |
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6 // /// \brief Maximum flow algorithms. |
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7 // /// \ingroup galgs |
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8 |
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9 namespace hugo { |
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10 |
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11 /// \brief A map for filtering the edge-set to those edges |
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12 /// which are tight w.r.t. some node_potential map and |
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13 /// edge_distance map. |
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14 /// |
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15 /// A node-map node_potential is said to be a potential w.r.t. |
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16 /// an edge-map edge_distance |
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17 /// if and only if for each edge e, node_potential[g.head(e)] |
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18 /// <= edge_distance[e]+node_potential[g.tail(e)] |
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19 /// (or the reverse inequality holds for each edge). |
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20 /// An edge is said to be tight if this inequality holds with equality, |
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21 /// and the map returns true exactly for those edges. |
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22 /// To avoid rounding errors, it is recommended to use this class with exact |
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23 /// types, e.g. with int. |
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24 template<typename Graph, |
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25 typename NodePotentialMap, typename EdgeDistanceMap> |
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26 class TightEdgeFilterMap { |
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27 protected: |
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28 const Graph* g; |
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29 NodePotentialMap* node_potential; |
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30 EdgeDistanceMap* edge_distance; |
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31 public: |
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32 TightEdgeFilterMap(Graph& _g, NodePotentialMap& _node_potential, |
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33 EdgeDistanceMap& _edge_distance) : |
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34 g(&_g), node_potential(&_node_potential), |
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35 edge_distance(&_edge_distance) { } |
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36 bool operator[](const typename Graph::Edge& e) const { |
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37 return ((*node_potential)[g->head(e)] == |
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38 (*edge_distance)[e]+(*node_potential)[g->tail(e)]); |
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39 } |
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40 }; |
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41 |
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42 } //namespace hugo |
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43 |
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44 #endif //HUGO_TIGHT_EDGE_FILTER_MAP_H |
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45 |
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46 |