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