[774] | 1 | // -*- C++ -*- |
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| 2 | #ifndef HUGO_BFS_H |
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| 3 | #define HUGO_BFS_H |
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| 4 | |
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| 5 | ///\ingroup flowalgs |
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| 6 | ///\file |
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| 7 | ///\brief Bfs algorithm. |
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| 8 | /// |
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| 9 | ///\todo Revise Manual. |
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| 10 | |
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| 11 | #include <hugo/bin_heap.h> |
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| 12 | #include <hugo/invalid.h> |
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| 13 | |
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| 14 | namespace hugo { |
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| 15 | |
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| 16 | /// \addtogroup flowalgs |
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| 17 | /// @{ |
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| 18 | |
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| 19 | ///%Bfs algorithm class. |
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| 20 | |
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| 21 | ///This class provides an efficient implementation of %Bfs algorithm. |
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| 22 | ///The edge lengths are passed to the algorithm using a |
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| 23 | ///\ref ReadMapSkeleton "readable map", |
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| 24 | ///so it is easy to change it to any kind of length. |
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| 25 | /// |
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| 26 | ///The type of the length is determined by the \c ValueType of the length map. |
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| 27 | /// |
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| 28 | ///It is also possible to change the underlying priority heap. |
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| 29 | /// |
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| 30 | ///\param GR The graph type the algorithm runs on. |
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| 31 | ///\param LM This read-only |
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| 32 | ///EdgeMap |
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| 33 | ///determines the |
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| 34 | ///lengths of the edges. It is read once for each edge, so the map |
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| 35 | ///may involve in relatively time consuming process to compute the edge |
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| 36 | ///length if it is necessary. The default map type is |
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| 37 | ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>" |
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| 38 | ///\param Heap The heap type used by the %Bfs |
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| 39 | ///algorithm. The default |
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| 40 | ///is using \ref BinHeap "binary heap". |
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| 41 | /// |
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| 42 | ///\author Jacint Szabo and Alpar Juttner |
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| 43 | ///\todo We need a typedef-names should be standardized. (-: |
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| 44 | ///\todo Type of \c PredMap, \c PredNodeMap and \c DistMap |
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| 45 | ///should not be fixed. (Problematic to solve). |
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| 46 | |
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| 47 | #ifdef DOXYGEN |
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| 48 | template <typename GR> |
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| 49 | #else |
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| 50 | template <typename GR> |
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| 51 | #endif |
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| 52 | class Bfs{ |
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| 53 | public: |
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| 54 | ///The type of the underlying graph. |
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| 55 | typedef GR Graph; |
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| 56 | typedef typename Graph::Node Node; |
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| 57 | typedef typename Graph::NodeIt NodeIt; |
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| 58 | typedef typename Graph::Edge Edge; |
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| 59 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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| 60 | |
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| 61 | ///\brief The type of the map that stores the last |
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| 62 | ///edges of the shortest paths. |
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| 63 | typedef typename Graph::template NodeMap<Edge> PredMap; |
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| 64 | ///\brief The type of the map that stores the last but one |
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| 65 | ///nodes of the shortest paths. |
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| 66 | typedef typename Graph::template NodeMap<Node> PredNodeMap; |
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| 67 | ///The type of the map that stores the dists of the nodes. |
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| 68 | typedef typename Graph::template NodeMap<int> DistMap; |
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| 69 | |
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| 70 | private: |
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| 71 | const Graph *G; |
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| 72 | PredMap *predecessor; |
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| 73 | bool local_predecessor; |
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| 74 | PredNodeMap *pred_node; |
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| 75 | bool local_pred_node; |
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| 76 | DistMap *distance; |
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| 77 | bool local_distance; |
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| 78 | |
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| 79 | //The source node of the last execution. |
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| 80 | Node source; |
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| 81 | |
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| 82 | |
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| 83 | ///Initialize maps. |
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| 84 | |
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| 85 | ///\todo Error if \c G or are \c NULL. |
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| 86 | ///\todo Better memory allocation (instead of new). |
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| 87 | void init_maps() |
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| 88 | { |
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| 89 | // if(!length) { |
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| 90 | // local_length = true; |
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| 91 | // length = new LM(G); |
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| 92 | // } |
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| 93 | if(!predecessor) { |
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| 94 | local_predecessor = true; |
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| 95 | predecessor = new PredMap(*G); |
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| 96 | } |
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| 97 | if(!pred_node) { |
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| 98 | local_pred_node = true; |
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| 99 | pred_node = new PredNodeMap(*G); |
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| 100 | } |
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| 101 | if(!distance) { |
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| 102 | local_distance = true; |
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| 103 | distance = new DistMap(*G); |
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| 104 | } |
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| 105 | } |
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| 106 | |
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| 107 | public : |
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| 108 | Bfs(const Graph& _G) : |
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| 109 | G(&_G), |
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| 110 | predecessor(NULL), local_predecessor(false), |
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| 111 | pred_node(NULL), local_pred_node(false), |
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| 112 | distance(NULL), local_distance(false) |
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| 113 | { } |
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| 114 | |
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| 115 | ~Bfs() |
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| 116 | { |
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| 117 | // if(local_length) delete length; |
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| 118 | if(local_predecessor) delete predecessor; |
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| 119 | if(local_pred_node) delete pred_node; |
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| 120 | if(local_distance) delete distance; |
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| 121 | } |
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| 122 | |
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| 123 | ///Sets the graph the algorithm will run on. |
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| 124 | |
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| 125 | ///Sets the graph the algorithm will run on. |
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| 126 | ///\return <tt> (*this) </tt> |
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| 127 | Bfs &setGraph(const Graph &_G) |
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| 128 | { |
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| 129 | G = &_G; |
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| 130 | return *this; |
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| 131 | } |
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| 132 | ///Sets the length map. |
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| 133 | |
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| 134 | ///Sets the map storing the predecessor edges. |
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| 135 | |
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| 136 | ///Sets the map storing the predecessor edges. |
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| 137 | ///If you don't use this function before calling \ref run(), |
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| 138 | ///it will allocate one. The destuctor deallocates this |
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| 139 | ///automatically allocated map, of course. |
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| 140 | ///\return <tt> (*this) </tt> |
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| 141 | Bfs &setPredMap(PredMap &m) |
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| 142 | { |
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| 143 | if(local_predecessor) { |
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| 144 | delete predecessor; |
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| 145 | local_predecessor=false; |
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| 146 | } |
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| 147 | predecessor = &m; |
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| 148 | return *this; |
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| 149 | } |
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| 150 | |
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| 151 | ///Sets the map storing the predecessor nodes. |
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| 152 | |
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| 153 | ///Sets the map storing the predecessor nodes. |
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| 154 | ///If you don't use this function before calling \ref run(), |
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| 155 | ///it will allocate one. The destuctor deallocates this |
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| 156 | ///automatically allocated map, of course. |
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| 157 | ///\return <tt> (*this) </tt> |
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| 158 | Bfs &setPredNodeMap(PredNodeMap &m) |
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| 159 | { |
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| 160 | if(local_pred_node) { |
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| 161 | delete pred_node; |
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| 162 | local_pred_node=false; |
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| 163 | } |
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| 164 | pred_node = &m; |
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| 165 | return *this; |
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| 166 | } |
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| 167 | |
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| 168 | ///Sets the map storing the distances calculated by the algorithm. |
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| 169 | |
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| 170 | ///Sets the map storing the distances calculated by the algorithm. |
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| 171 | ///If you don't use this function before calling \ref run(), |
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| 172 | ///it will allocate one. The destuctor deallocates this |
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| 173 | ///automatically allocated map, of course. |
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| 174 | ///\return <tt> (*this) </tt> |
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| 175 | Bfs &setDistMap(DistMap &m) |
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| 176 | { |
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| 177 | if(local_distance) { |
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| 178 | delete distance; |
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| 179 | local_distance=false; |
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| 180 | } |
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| 181 | distance = &m; |
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| 182 | return *this; |
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| 183 | } |
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| 184 | |
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| 185 | ///Runs %BFS algorithm from node \c s. |
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| 186 | |
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| 187 | ///This method runs the %BFS algorithm from a root node \c s |
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| 188 | ///in order to |
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| 189 | ///compute the |
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| 190 | ///shortest path to each node. The algorithm computes |
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| 191 | ///- The shortest path tree. |
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| 192 | ///- The distance of each node from the root. |
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| 193 | |
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| 194 | void run(Node s) { |
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| 195 | |
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| 196 | init_maps(); |
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| 197 | |
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| 198 | source = s; |
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| 199 | |
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| 200 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
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| 201 | predecessor->set(u,INVALID); |
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| 202 | pred_node->set(u,INVALID); |
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| 203 | } |
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| 204 | |
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| 205 | int N=G->nodeNum(); |
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| 206 | std::vector<typename Graph::Node> Q(N); |
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| 207 | int Qh=0; |
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| 208 | int Qt=0; |
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| 209 | |
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| 210 | Q[Qh++]=source; |
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| 211 | distance->set(s, 0); |
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| 212 | do { |
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| 213 | Node m; |
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| 214 | Node n=Q[Qt++]; |
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| 215 | int d= (*distance)[n]+1; |
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| 216 | |
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| 217 | for(OutEdgeIt e(*G,n);e!=INVALID;++e) |
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| 218 | if((m=G->head(e))!=s && (*predecessor)[m]==INVALID) { |
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| 219 | Q[Qh++]=m; |
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| 220 | predecessor->set(m,e); |
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| 221 | pred_node->set(m,n); |
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| 222 | distance->set(m,d); |
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| 223 | } |
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| 224 | } while(Qt!=Qh); |
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| 225 | } |
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| 226 | |
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| 227 | ///The distance of a node from the root. |
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| 228 | |
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| 229 | ///Returns the distance of a node from the root. |
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| 230 | ///\pre \ref run() must be called before using this function. |
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| 231 | ///\warning If node \c v in unreachable from the root the return value |
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| 232 | ///of this funcion is undefined. |
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| 233 | int dist(Node v) const { return (*distance)[v]; } |
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| 234 | |
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| 235 | ///Returns the 'previous edge' of the shortest path tree. |
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| 236 | |
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| 237 | ///For a node \c v it returns the 'previous edge' of the shortest path tree, |
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| 238 | ///i.e. it returns the last edge from a shortest path from the root to \c |
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| 239 | ///v. It is \ref INVALID |
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| 240 | ///if \c v is unreachable from the root or if \c v=s. The |
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| 241 | ///shortest path tree used here is equal to the shortest path tree used in |
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| 242 | ///\ref predNode(Node v). \pre \ref run() must be called before using |
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| 243 | ///this function. |
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| 244 | Edge pred(Node v) const { return (*predecessor)[v]; } |
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| 245 | |
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| 246 | ///Returns the 'previous node' of the shortest path tree. |
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| 247 | |
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| 248 | ///For a node \c v it returns the 'previous node' of the shortest path tree, |
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| 249 | ///i.e. it returns the last but one node from a shortest path from the |
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| 250 | ///root to \c /v. It is INVALID if \c v is unreachable from the root or if |
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| 251 | ///\c v=s. The shortest path tree used here is equal to the shortest path |
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| 252 | ///tree used in \ref pred(Node v). \pre \ref run() must be called before |
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| 253 | ///using this function. |
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| 254 | Node predNode(Node v) const { return (*pred_node)[v]; } |
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| 255 | |
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| 256 | ///Returns a reference to the NodeMap of distances. |
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| 257 | |
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| 258 | ///Returns a reference to the NodeMap of distances. \pre \ref run() must |
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| 259 | ///be called before using this function. |
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| 260 | const DistMap &distMap() const { return *distance;} |
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| 261 | |
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| 262 | ///Returns a reference to the shortest path tree map. |
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| 263 | |
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| 264 | ///Returns a reference to the NodeMap of the edges of the |
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| 265 | ///shortest path tree. |
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| 266 | ///\pre \ref run() must be called before using this function. |
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| 267 | const PredMap &predMap() const { return *predecessor;} |
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| 268 | |
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| 269 | ///Returns a reference to the map of nodes of shortest paths. |
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| 270 | |
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| 271 | ///Returns a reference to the NodeMap of the last but one nodes of the |
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| 272 | ///shortest path tree. |
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| 273 | ///\pre \ref run() must be called before using this function. |
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| 274 | const PredNodeMap &predNodeMap() const { return *pred_node;} |
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| 275 | |
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| 276 | ///Checks if a node is reachable from the root. |
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| 277 | |
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| 278 | ///Returns \c true if \c v is reachable from the root. |
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| 279 | ///\warning The root node is reported to be reached! |
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| 280 | /// |
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| 281 | ///\pre \ref run() must be called before using this function. |
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| 282 | /// |
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| 283 | bool reached(Node v) { return v==source || (*predecessor)[v]==INVALID; } |
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| 284 | |
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| 285 | }; |
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| 286 | |
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| 287 | |
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| 288 | // ********************************************************************** |
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| 289 | // IMPLEMENTATIONS |
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| 290 | // ********************************************************************** |
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| 291 | |
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| 292 | /// @} |
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| 293 | |
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| 294 | } //END OF NAMESPACE HUGO |
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| 295 | |
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| 296 | #endif |
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| 297 | |
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| 298 | |
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