1.1 --- a/src/lemon/dijkstra.h Sun Feb 06 20:00:56 2005 +0000
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,344 +0,0 @@
1.4 -/* -*- C++ -*-
1.5 - * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library
1.6 - *
1.7 - * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
1.8 - * (Egervary Combinatorial Optimization Research Group, EGRES).
1.9 - *
1.10 - * Permission to use, modify and distribute this software is granted
1.11 - * provided that this copyright notice appears in all copies. For
1.12 - * precise terms see the accompanying LICENSE file.
1.13 - *
1.14 - * This software is provided "AS IS" with no warranty of any kind,
1.15 - * express or implied, and with no claim as to its suitability for any
1.16 - * purpose.
1.17 - *
1.18 - */
1.19 -
1.20 -#ifndef LEMON_DIJKSTRA_H
1.21 -#define LEMON_DIJKSTRA_H
1.22 -
1.23 -///\ingroup flowalgs
1.24 -///\file
1.25 -///\brief Dijkstra algorithm.
1.26 -
1.27 -#include <lemon/bin_heap.h>
1.28 -#include <lemon/invalid.h>
1.29 -
1.30 -namespace lemon {
1.31 -
1.32 -/// \addtogroup flowalgs
1.33 -/// @{
1.34 -
1.35 - ///%Dijkstra algorithm class.
1.36 -
1.37 - ///This class provides an efficient implementation of %Dijkstra algorithm.
1.38 - ///The edge lengths are passed to the algorithm using a
1.39 - ///\ref concept::ReadMap "ReadMap",
1.40 - ///so it is easy to change it to any kind of length.
1.41 - ///
1.42 - ///The type of the length is determined by the
1.43 - ///\ref concept::ReadMap::Value "Value" of the length map.
1.44 - ///
1.45 - ///It is also possible to change the underlying priority heap.
1.46 - ///
1.47 - ///\param GR The graph type the algorithm runs on.
1.48 - ///\param LM This read-only
1.49 - ///EdgeMap
1.50 - ///determines the
1.51 - ///lengths of the edges. It is read once for each edge, so the map
1.52 - ///may involve in relatively time consuming process to compute the edge
1.53 - ///length if it is necessary. The default map type is
1.54 - ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>"
1.55 - ///\param Heap The heap type used by the %Dijkstra
1.56 - ///algorithm. The default
1.57 - ///is using \ref BinHeap "binary heap".
1.58 - ///
1.59 - ///\author Jacint Szabo and Alpar Juttner
1.60 - ///\todo We need a typedef-names should be standardized. (-:
1.61 - ///\todo Type of \c PredMap, \c PredNodeMap and \c DistMap
1.62 - ///should not be fixed. (Problematic to solve).
1.63 -
1.64 -#ifdef DOXYGEN
1.65 - template <typename GR,
1.66 - typename LM,
1.67 - typename Heap>
1.68 -#else
1.69 - template <typename GR,
1.70 - typename LM=typename GR::template EdgeMap<int>,
1.71 - template <class,class,class,class> class Heap = BinHeap >
1.72 -#endif
1.73 - class Dijkstra{
1.74 - public:
1.75 - ///The type of the underlying graph.
1.76 - typedef GR Graph;
1.77 - ///\e
1.78 - typedef typename Graph::Node Node;
1.79 - ///\e
1.80 - typedef typename Graph::NodeIt NodeIt;
1.81 - ///\e
1.82 - typedef typename Graph::Edge Edge;
1.83 - ///\e
1.84 - typedef typename Graph::OutEdgeIt OutEdgeIt;
1.85 -
1.86 - ///The type of the length of the edges.
1.87 - typedef typename LM::Value Value;
1.88 - ///The type of the map that stores the edge lengths.
1.89 - typedef LM LengthMap;
1.90 - ///\brief The type of the map that stores the last
1.91 - ///edges of the shortest paths.
1.92 - typedef typename Graph::template NodeMap<Edge> PredMap;
1.93 - ///\brief The type of the map that stores the last but one
1.94 - ///nodes of the shortest paths.
1.95 - typedef typename Graph::template NodeMap<Node> PredNodeMap;
1.96 - ///The type of the map that stores the dists of the nodes.
1.97 - typedef typename Graph::template NodeMap<Value> DistMap;
1.98 -
1.99 - private:
1.100 - /// Pointer to the underlying graph.
1.101 - const Graph *G;
1.102 - /// Pointer to the length map
1.103 - const LM *length;
1.104 - ///Pointer to the map of predecessors edges.
1.105 - PredMap *predecessor;
1.106 - ///Indicates if \ref predecessor is locally allocated (\c true) or not.
1.107 - bool local_predecessor;
1.108 - ///Pointer to the map of predecessors nodes.
1.109 - PredNodeMap *pred_node;
1.110 - ///Indicates if \ref pred_node is locally allocated (\c true) or not.
1.111 - bool local_pred_node;
1.112 - ///Pointer to the map of distances.
1.113 - DistMap *distance;
1.114 - ///Indicates if \ref distance is locally allocated (\c true) or not.
1.115 - bool local_distance;
1.116 -
1.117 - ///The source node of the last execution.
1.118 - Node source;
1.119 -
1.120 - ///Initializes the maps.
1.121 -
1.122 - ///\todo Error if \c G or are \c NULL. What about \c length?
1.123 - ///\todo Better memory allocation (instead of new).
1.124 - void init_maps()
1.125 - {
1.126 - if(!predecessor) {
1.127 - local_predecessor = true;
1.128 - predecessor = new PredMap(*G);
1.129 - }
1.130 - if(!pred_node) {
1.131 - local_pred_node = true;
1.132 - pred_node = new PredNodeMap(*G);
1.133 - }
1.134 - if(!distance) {
1.135 - local_distance = true;
1.136 - distance = new DistMap(*G);
1.137 - }
1.138 - }
1.139 -
1.140 - public :
1.141 - ///Constructor.
1.142 -
1.143 - ///\param _G the graph the algorithm will run on.
1.144 - ///\param _length the length map used by the algorithm.
1.145 - Dijkstra(const Graph& _G, const LM& _length) :
1.146 - G(&_G), length(&_length),
1.147 - predecessor(NULL), local_predecessor(false),
1.148 - pred_node(NULL), local_pred_node(false),
1.149 - distance(NULL), local_distance(false)
1.150 - { }
1.151 -
1.152 - ///Destructor.
1.153 - ~Dijkstra()
1.154 - {
1.155 - if(local_predecessor) delete predecessor;
1.156 - if(local_pred_node) delete pred_node;
1.157 - if(local_distance) delete distance;
1.158 - }
1.159 -
1.160 - ///Sets the length map.
1.161 -
1.162 - ///Sets the length map.
1.163 - ///\return <tt> (*this) </tt>
1.164 - Dijkstra &setLengthMap(const LM &m)
1.165 - {
1.166 - length = &m;
1.167 - return *this;
1.168 - }
1.169 -
1.170 - ///Sets the map storing the predecessor edges.
1.171 -
1.172 - ///Sets the map storing the predecessor edges.
1.173 - ///If you don't use this function before calling \ref run(),
1.174 - ///it will allocate one. The destuctor deallocates this
1.175 - ///automatically allocated map, of course.
1.176 - ///\return <tt> (*this) </tt>
1.177 - Dijkstra &setPredMap(PredMap &m)
1.178 - {
1.179 - if(local_predecessor) {
1.180 - delete predecessor;
1.181 - local_predecessor=false;
1.182 - }
1.183 - predecessor = &m;
1.184 - return *this;
1.185 - }
1.186 -
1.187 - ///Sets the map storing the predecessor nodes.
1.188 -
1.189 - ///Sets the map storing the predecessor nodes.
1.190 - ///If you don't use this function before calling \ref run(),
1.191 - ///it will allocate one. The destuctor deallocates this
1.192 - ///automatically allocated map, of course.
1.193 - ///\return <tt> (*this) </tt>
1.194 - Dijkstra &setPredNodeMap(PredNodeMap &m)
1.195 - {
1.196 - if(local_pred_node) {
1.197 - delete pred_node;
1.198 - local_pred_node=false;
1.199 - }
1.200 - pred_node = &m;
1.201 - return *this;
1.202 - }
1.203 -
1.204 - ///Sets the map storing the distances calculated by the algorithm.
1.205 -
1.206 - ///Sets the map storing the distances calculated by the algorithm.
1.207 - ///If you don't use this function before calling \ref run(),
1.208 - ///it will allocate one. The destuctor deallocates this
1.209 - ///automatically allocated map, of course.
1.210 - ///\return <tt> (*this) </tt>
1.211 - Dijkstra &setDistMap(DistMap &m)
1.212 - {
1.213 - if(local_distance) {
1.214 - delete distance;
1.215 - local_distance=false;
1.216 - }
1.217 - distance = &m;
1.218 - return *this;
1.219 - }
1.220 -
1.221 - ///Runs %Dijkstra algorithm from node \c s.
1.222 -
1.223 - ///This method runs the %Dijkstra algorithm from a root node \c s
1.224 - ///in order to
1.225 - ///compute the
1.226 - ///shortest path to each node. The algorithm computes
1.227 - ///- The shortest path tree.
1.228 - ///- The distance of each node from the root.
1.229 -
1.230 - void run(Node s) {
1.231 -
1.232 - init_maps();
1.233 -
1.234 - source = s;
1.235 -
1.236 - for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
1.237 - predecessor->set(u,INVALID);
1.238 - pred_node->set(u,INVALID);
1.239 - }
1.240 -
1.241 - typename GR::template NodeMap<int> heap_map(*G,-1);
1.242 -
1.243 - typedef Heap<Node, Value, typename GR::template NodeMap<int>,
1.244 - std::less<Value> >
1.245 - HeapType;
1.246 -
1.247 - HeapType heap(heap_map);
1.248 -
1.249 - heap.push(s,0);
1.250 -
1.251 - while ( !heap.empty() ) {
1.252 -
1.253 - Node v=heap.top();
1.254 - Value oldvalue=heap[v];
1.255 - heap.pop();
1.256 - distance->set(v, oldvalue);
1.257 -
1.258 -
1.259 - for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
1.260 - Node w=G->target(e);
1.261 - switch(heap.state(w)) {
1.262 - case HeapType::PRE_HEAP:
1.263 - heap.push(w,oldvalue+(*length)[e]);
1.264 - predecessor->set(w,e);
1.265 - pred_node->set(w,v);
1.266 - break;
1.267 - case HeapType::IN_HEAP:
1.268 - if ( oldvalue+(*length)[e] < heap[w] ) {
1.269 - heap.decrease(w, oldvalue+(*length)[e]);
1.270 - predecessor->set(w,e);
1.271 - pred_node->set(w,v);
1.272 - }
1.273 - break;
1.274 - case HeapType::POST_HEAP:
1.275 - break;
1.276 - }
1.277 - }
1.278 - }
1.279 - }
1.280 -
1.281 - ///The distance of a node from the root.
1.282 -
1.283 - ///Returns the distance of a node from the root.
1.284 - ///\pre \ref run() must be called before using this function.
1.285 - ///\warning If node \c v in unreachable from the root the return value
1.286 - ///of this funcion is undefined.
1.287 - Value dist(Node v) const { return (*distance)[v]; }
1.288 -
1.289 - ///Returns the 'previous edge' of the shortest path tree.
1.290 -
1.291 - ///For a node \c v it returns the 'previous edge' of the shortest path tree,
1.292 - ///i.e. it returns the last edge of a shortest path from the root to \c
1.293 - ///v. It is \ref INVALID
1.294 - ///if \c v is unreachable from the root or if \c v=s. The
1.295 - ///shortest path tree used here is equal to the shortest path tree used in
1.296 - ///\ref predNode(Node v). \pre \ref run() must be called before using
1.297 - ///this function.
1.298 - ///\todo predEdge could be a better name.
1.299 - Edge pred(Node v) const { return (*predecessor)[v]; }
1.300 -
1.301 - ///Returns the 'previous node' of the shortest path tree.
1.302 -
1.303 - ///For a node \c v it returns the 'previous node' of the shortest path tree,
1.304 - ///i.e. it returns the last but one node from a shortest path from the
1.305 - ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
1.306 - ///\c v=s. The shortest path tree used here is equal to the shortest path
1.307 - ///tree used in \ref pred(Node v). \pre \ref run() must be called before
1.308 - ///using this function.
1.309 - Node predNode(Node v) const { return (*pred_node)[v]; }
1.310 -
1.311 - ///Returns a reference to the NodeMap of distances.
1.312 -
1.313 - ///Returns a reference to the NodeMap of distances. \pre \ref run() must
1.314 - ///be called before using this function.
1.315 - const DistMap &distMap() const { return *distance;}
1.316 -
1.317 - ///Returns a reference to the shortest path tree map.
1.318 -
1.319 - ///Returns a reference to the NodeMap of the edges of the
1.320 - ///shortest path tree.
1.321 - ///\pre \ref run() must be called before using this function.
1.322 - const PredMap &predMap() const { return *predecessor;}
1.323 -
1.324 - ///Returns a reference to the map of nodes of shortest paths.
1.325 -
1.326 - ///Returns a reference to the NodeMap of the last but one nodes of the
1.327 - ///shortest path tree.
1.328 - ///\pre \ref run() must be called before using this function.
1.329 - const PredNodeMap &predNodeMap() const { return *pred_node;}
1.330 -
1.331 - ///Checks if a node is reachable from the root.
1.332 -
1.333 - ///Returns \c true if \c v is reachable from the root.
1.334 - ///\note The root node is reported to be reached!
1.335 - ///\pre \ref run() must be called before using this function.
1.336 - ///
1.337 - bool reached(Node v) { return v==source || (*predecessor)[v]!=INVALID; }
1.338 -
1.339 - };
1.340 -
1.341 -/// @}
1.342 -
1.343 -} //END OF NAMESPACE LEMON
1.344 -
1.345 -#endif
1.346 -
1.347 -