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