1 /* -*- C++ -*- |
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2 * src/hugo/tight_edge_filter_map.h - Part of HUGOlib, a generic C++ optimization library |
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3 * |
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4 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 * (Egervary Combinatorial Optimization Research Group, EGRES). |
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6 * |
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7 * Permission to use, modify and distribute this software is granted |
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8 * provided that this copyright notice appears in all copies. For |
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9 * precise terms see the accompanying LICENSE file. |
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10 * |
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11 * This software is provided "AS IS" with no warranty of any kind, |
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12 * express or implied, and with no claim as to its suitability for any |
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13 * purpose. |
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14 * |
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15 */ |
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16 |
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17 #ifndef HUGO_TIGHT_EDGE_FILTER_MAP_H |
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18 #define HUGO_TIGHT_EDGE_FILTER_MAP_H |
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19 |
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20 #include <hugo/maps.h> |
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21 |
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22 // /// \file |
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23 // /// \brief Maximum flow algorithms. |
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24 // /// \ingroup galgs |
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25 |
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26 namespace hugo { |
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27 |
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28 /// \brief A map for filtering the edge-set to those edges |
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29 /// which are tight w.r.t. some node_potential map and |
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30 /// edge_distance map. |
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31 /// |
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32 /// A node-map node_potential is said to be a potential w.r.t. |
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33 /// an edge-map edge_distance |
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34 /// if and only if for each edge e, node_potential[g.head(e)] |
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35 /// <= edge_distance[e]+node_potential[g.tail(e)] |
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36 /// (or the reverse inequality holds for each edge). |
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37 /// An edge is said to be tight if this inequality holds with equality, |
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38 /// and the map returns true exactly for those edges. |
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39 /// To avoid rounding errors, it is recommended to use this class with exact |
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40 /// types, e.g. with int. |
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41 template<typename Graph, |
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42 typename NodePotentialMap, typename EdgeDistanceMap> |
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43 class TightEdgeFilterMap : public MapBase<typename Graph::Edge, bool> { |
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44 protected: |
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45 const Graph* g; |
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46 NodePotentialMap* node_potential; |
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47 EdgeDistanceMap* edge_distance; |
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48 public: |
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49 TightEdgeFilterMap(Graph& _g, NodePotentialMap& _node_potential, |
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50 EdgeDistanceMap& _edge_distance) : |
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51 g(&_g), node_potential(&_node_potential), |
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52 edge_distance(&_edge_distance) { } |
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53 bool operator[](const typename Graph::Edge& e) const { |
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54 return ((*node_potential)[g->head(e)] == |
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55 (*edge_distance)[e]+(*node_potential)[g->tail(e)]); |
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56 } |
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57 }; |
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58 |
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59 } //namespace hugo |
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60 |
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61 #endif //HUGO_TIGHT_EDGE_FILTER_MAP_H |
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62 |
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63 |
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