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| ... | ... |
@@ -24,82 +24,84 @@ |
| 24 | 24 |
///\brief An algorithm for finding arc-disjoint paths between two |
| 25 | 25 |
/// nodes having minimum total length. |
| 26 | 26 |
|
| 27 | 27 |
#include <vector> |
| 28 | 28 |
#include <lemon/bin_heap.h> |
| 29 | 29 |
#include <lemon/path.h> |
| 30 | 30 |
|
| 31 | 31 |
namespace lemon {
|
| 32 | 32 |
|
| 33 | 33 |
/// \addtogroup shortest_path |
| 34 | 34 |
/// @{
|
| 35 | 35 |
|
| 36 |
/// \brief Implementation of an algorithm for finding arc-disjoint |
|
| 37 |
/// paths between two nodes having minimum total length. |
|
| 36 |
/// \brief Algorithm for finding arc-disjoint paths between two nodes |
|
| 37 |
/// having minimum total length. |
|
| 38 | 38 |
/// |
| 39 | 39 |
/// \ref lemon::Suurballe "Suurballe" implements an algorithm for |
| 40 | 40 |
/// finding arc-disjoint paths having minimum total length (cost) |
| 41 |
/// from a given source node to a given target node in a directed |
|
| 42 |
/// digraph. |
|
| 41 |
/// from a given source node to a given target node in a digraph. |
|
| 43 | 42 |
/// |
| 44 | 43 |
/// In fact, this implementation is the specialization of the |
| 45 | 44 |
/// \ref CapacityScaling "successive shortest path" algorithm. |
| 46 | 45 |
/// |
| 47 |
/// \tparam Digraph The |
|
| 46 |
/// \tparam Digraph The digraph type the algorithm runs on. |
|
| 47 |
/// The default value is \c ListDigraph. |
|
| 48 | 48 |
/// \tparam LengthMap The type of the length (cost) map. |
| 49 |
/// The default value is <tt>Digraph::ArcMap<int></tt>. |
|
| 49 | 50 |
/// |
| 50 | 51 |
/// \warning Length values should be \e non-negative \e integers. |
| 51 | 52 |
/// |
| 52 | 53 |
/// \note For finding node-disjoint paths this algorithm can be used |
| 53 | 54 |
/// with \ref SplitDigraphAdaptor. |
| 54 |
/// |
|
| 55 |
/// \author Attila Bernath and Peter Kovacs |
|
| 56 |
|
|
| 57 |
template < typename Digraph, |
|
| 55 |
#ifdef DOXYGEN |
|
| 56 |
template <typename Digraph, typename LengthMap> |
|
| 57 |
#else |
|
| 58 |
template < typename Digraph = ListDigraph, |
|
| 58 | 59 |
typename LengthMap = typename Digraph::template ArcMap<int> > |
| 60 |
#endif |
|
| 59 | 61 |
class Suurballe |
| 60 | 62 |
{
|
| 61 | 63 |
TEMPLATE_DIGRAPH_TYPEDEFS(Digraph); |
| 62 | 64 |
|
| 63 | 65 |
typedef typename LengthMap::Value Length; |
| 64 | 66 |
typedef ConstMap<Arc, int> ConstArcMap; |
| 65 | 67 |
typedef typename Digraph::template NodeMap<Arc> PredMap; |
| 66 | 68 |
|
| 67 | 69 |
public: |
| 68 | 70 |
|
| 69 | 71 |
/// The type of the flow map. |
| 70 | 72 |
typedef typename Digraph::template ArcMap<int> FlowMap; |
| 71 | 73 |
/// The type of the potential map. |
| 72 | 74 |
typedef typename Digraph::template NodeMap<Length> PotentialMap; |
| 73 | 75 |
/// The type of the path structures. |
| 74 | 76 |
typedef SimplePath<Digraph> Path; |
| 75 | 77 |
|
| 76 | 78 |
private: |
| 77 | 79 |
|
| 78 |
/// \brief Special implementation of the |
|
| 80 |
/// \brief Special implementation of the Dijkstra algorithm |
|
| 79 | 81 |
/// for finding shortest paths in the residual network. |
| 80 | 82 |
/// |
| 81 | 83 |
/// \ref ResidualDijkstra is a special implementation of the |
| 82 | 84 |
/// \ref Dijkstra algorithm for finding shortest paths in the |
| 83 | 85 |
/// residual network of the digraph with respect to the reduced arc |
| 84 | 86 |
/// lengths and modifying the node potentials according to the |
| 85 | 87 |
/// distance of the nodes. |
| 86 | 88 |
class ResidualDijkstra |
| 87 | 89 |
{
|
| 88 | 90 |
typedef typename Digraph::template NodeMap<int> HeapCrossRef; |
| 89 | 91 |
typedef BinHeap<Length, HeapCrossRef> Heap; |
| 90 | 92 |
|
| 91 | 93 |
private: |
| 92 | 94 |
|
| 93 |
// The |
|
| 95 |
// The digraph the algorithm runs on |
|
| 94 | 96 |
const Digraph &_graph; |
| 95 | 97 |
|
| 96 | 98 |
// The main maps |
| 97 | 99 |
const FlowMap &_flow; |
| 98 | 100 |
const LengthMap &_length; |
| 99 | 101 |
PotentialMap &_potential; |
| 100 | 102 |
|
| 101 | 103 |
// The distance map |
| 102 | 104 |
PotentialMap _dist; |
| 103 | 105 |
// The pred arc map |
| 104 | 106 |
PredMap &_pred; |
| 105 | 107 |
// The processed (i.e. permanently labeled) nodes |
| ... | ... |
@@ -111,99 +113,99 @@ |
| 111 | 113 |
public: |
| 112 | 114 |
|
| 113 | 115 |
/// Constructor. |
| 114 | 116 |
ResidualDijkstra( const Digraph &digraph, |
| 115 | 117 |
const FlowMap &flow, |
| 116 | 118 |
const LengthMap &length, |
| 117 | 119 |
PotentialMap &potential, |
| 118 | 120 |
PredMap &pred, |
| 119 | 121 |
Node s, Node t ) : |
| 120 | 122 |
_graph(digraph), _flow(flow), _length(length), _potential(potential), |
| 121 | 123 |
_dist(digraph), _pred(pred), _s(s), _t(t) {}
|
| 122 | 124 |
|
| 123 |
/// \brief |
|
| 125 |
/// \brief Run the algorithm. It returns \c true if a path is found |
|
| 124 | 126 |
/// from the source node to the target node. |
| 125 | 127 |
bool run() {
|
| 126 | 128 |
HeapCrossRef heap_cross_ref(_graph, Heap::PRE_HEAP); |
| 127 | 129 |
Heap heap(heap_cross_ref); |
| 128 | 130 |
heap.push(_s, 0); |
| 129 | 131 |
_pred[_s] = INVALID; |
| 130 | 132 |
_proc_nodes.clear(); |
| 131 | 133 |
|
| 132 |
// |
|
| 134 |
// Process nodes |
|
| 133 | 135 |
while (!heap.empty() && heap.top() != _t) {
|
| 134 | 136 |
Node u = heap.top(), v; |
| 135 | 137 |
Length d = heap.prio() + _potential[u], nd; |
| 136 | 138 |
_dist[u] = heap.prio(); |
| 137 | 139 |
heap.pop(); |
| 138 | 140 |
_proc_nodes.push_back(u); |
| 139 | 141 |
|
| 140 |
// |
|
| 142 |
// Traverse outgoing arcs |
|
| 141 | 143 |
for (OutArcIt e(_graph, u); e != INVALID; ++e) {
|
| 142 | 144 |
if (_flow[e] == 0) {
|
| 143 | 145 |
v = _graph.target(e); |
| 144 | 146 |
switch(heap.state(v)) {
|
| 145 | 147 |
case Heap::PRE_HEAP: |
| 146 | 148 |
heap.push(v, d + _length[e] - _potential[v]); |
| 147 | 149 |
_pred[v] = e; |
| 148 | 150 |
break; |
| 149 | 151 |
case Heap::IN_HEAP: |
| 150 | 152 |
nd = d + _length[e] - _potential[v]; |
| 151 | 153 |
if (nd < heap[v]) {
|
| 152 | 154 |
heap.decrease(v, nd); |
| 153 | 155 |
_pred[v] = e; |
| 154 | 156 |
} |
| 155 | 157 |
break; |
| 156 | 158 |
case Heap::POST_HEAP: |
| 157 | 159 |
break; |
| 158 | 160 |
} |
| 159 | 161 |
} |
| 160 | 162 |
} |
| 161 | 163 |
|
| 162 |
// |
|
| 164 |
// Traverse incoming arcs |
|
| 163 | 165 |
for (InArcIt e(_graph, u); e != INVALID; ++e) {
|
| 164 | 166 |
if (_flow[e] == 1) {
|
| 165 | 167 |
v = _graph.source(e); |
| 166 | 168 |
switch(heap.state(v)) {
|
| 167 | 169 |
case Heap::PRE_HEAP: |
| 168 | 170 |
heap.push(v, d - _length[e] - _potential[v]); |
| 169 | 171 |
_pred[v] = e; |
| 170 | 172 |
break; |
| 171 | 173 |
case Heap::IN_HEAP: |
| 172 | 174 |
nd = d - _length[e] - _potential[v]; |
| 173 | 175 |
if (nd < heap[v]) {
|
| 174 | 176 |
heap.decrease(v, nd); |
| 175 | 177 |
_pred[v] = e; |
| 176 | 178 |
} |
| 177 | 179 |
break; |
| 178 | 180 |
case Heap::POST_HEAP: |
| 179 | 181 |
break; |
| 180 | 182 |
} |
| 181 | 183 |
} |
| 182 | 184 |
} |
| 183 | 185 |
} |
| 184 | 186 |
if (heap.empty()) return false; |
| 185 | 187 |
|
| 186 |
// |
|
| 188 |
// Update potentials of processed nodes |
|
| 187 | 189 |
Length t_dist = heap.prio(); |
| 188 | 190 |
for (int i = 0; i < int(_proc_nodes.size()); ++i) |
| 189 | 191 |
_potential[_proc_nodes[i]] += _dist[_proc_nodes[i]] - t_dist; |
| 190 | 192 |
return true; |
| 191 | 193 |
} |
| 192 | 194 |
|
| 193 | 195 |
}; //class ResidualDijkstra |
| 194 | 196 |
|
| 195 | 197 |
private: |
| 196 | 198 |
|
| 197 |
// The |
|
| 199 |
// The digraph the algorithm runs on |
|
| 198 | 200 |
const Digraph &_graph; |
| 199 | 201 |
// The length map |
| 200 | 202 |
const LengthMap &_length; |
| 201 | 203 |
|
| 202 | 204 |
// Arc map of the current flow |
| 203 | 205 |
FlowMap *_flow; |
| 204 | 206 |
bool _local_flow; |
| 205 | 207 |
// Node map of the current potentials |
| 206 | 208 |
PotentialMap *_potential; |
| 207 | 209 |
bool _local_potential; |
| 208 | 210 |
|
| 209 | 211 |
// The source node |
| ... | ... |
@@ -218,281 +220,281 @@ |
| 218 | 220 |
// The pred arc map |
| 219 | 221 |
PredMap _pred; |
| 220 | 222 |
// Implementation of the Dijkstra algorithm for finding augmenting |
| 221 | 223 |
// shortest paths in the residual network |
| 222 | 224 |
ResidualDijkstra *_dijkstra; |
| 223 | 225 |
|
| 224 | 226 |
public: |
| 225 | 227 |
|
| 226 | 228 |
/// \brief Constructor. |
| 227 | 229 |
/// |
| 228 | 230 |
/// Constructor. |
| 229 | 231 |
/// |
| 230 |
/// \param digraph The |
|
| 232 |
/// \param digraph The digraph the algorithm runs on. |
|
| 231 | 233 |
/// \param length The length (cost) values of the arcs. |
| 232 | 234 |
/// \param s The source node. |
| 233 | 235 |
/// \param t The target node. |
| 234 | 236 |
Suurballe( const Digraph &digraph, |
| 235 | 237 |
const LengthMap &length, |
| 236 | 238 |
Node s, Node t ) : |
| 237 | 239 |
_graph(digraph), _length(length), _flow(0), _local_flow(false), |
| 238 | 240 |
_potential(0), _local_potential(false), _source(s), _target(t), |
| 239 | 241 |
_pred(digraph) {}
|
| 240 | 242 |
|
| 241 | 243 |
/// Destructor. |
| 242 | 244 |
~Suurballe() {
|
| 243 | 245 |
if (_local_flow) delete _flow; |
| 244 | 246 |
if (_local_potential) delete _potential; |
| 245 | 247 |
delete _dijkstra; |
| 246 | 248 |
} |
| 247 | 249 |
|
| 248 |
/// \brief |
|
| 250 |
/// \brief Set the flow map. |
|
| 249 | 251 |
/// |
| 250 |
/// |
|
| 252 |
/// This function sets the flow map. |
|
| 251 | 253 |
/// |
| 252 | 254 |
/// The found flow contains only 0 and 1 values. It is the union of |
| 253 | 255 |
/// the found arc-disjoint paths. |
| 254 | 256 |
/// |
| 255 | 257 |
/// \return \c (*this) |
| 256 | 258 |
Suurballe& flowMap(FlowMap &map) {
|
| 257 | 259 |
if (_local_flow) {
|
| 258 | 260 |
delete _flow; |
| 259 | 261 |
_local_flow = false; |
| 260 | 262 |
} |
| 261 | 263 |
_flow = ↦ |
| 262 | 264 |
return *this; |
| 263 | 265 |
} |
| 264 | 266 |
|
| 265 |
/// \brief |
|
| 267 |
/// \brief Set the potential map. |
|
| 266 | 268 |
/// |
| 267 |
/// |
|
| 269 |
/// This function sets the potential map. |
|
| 268 | 270 |
/// |
| 269 | 271 |
/// The potentials provide the dual solution of the underlying |
| 270 | 272 |
/// minimum cost flow problem. |
| 271 | 273 |
/// |
| 272 | 274 |
/// \return \c (*this) |
| 273 | 275 |
Suurballe& potentialMap(PotentialMap &map) {
|
| 274 | 276 |
if (_local_potential) {
|
| 275 | 277 |
delete _potential; |
| 276 | 278 |
_local_potential = false; |
| 277 | 279 |
} |
| 278 | 280 |
_potential = ↦ |
| 279 | 281 |
return *this; |
| 280 | 282 |
} |
| 281 | 283 |
|
| 282 | 284 |
/// \name Execution control |
| 283 | 285 |
/// The simplest way to execute the algorithm is to call the run() |
| 284 | 286 |
/// function. |
| 285 | 287 |
/// \n |
| 286 | 288 |
/// If you only need the flow that is the union of the found |
| 287 | 289 |
/// arc-disjoint paths, you may call init() and findFlow(). |
| 288 | 290 |
|
| 289 | 291 |
/// @{
|
| 290 | 292 |
|
| 291 |
/// \brief |
|
| 293 |
/// \brief Run the algorithm. |
|
| 292 | 294 |
/// |
| 293 |
/// |
|
| 295 |
/// This function runs the algorithm. |
|
| 294 | 296 |
/// |
| 295 | 297 |
/// \param k The number of paths to be found. |
| 296 | 298 |
/// |
| 297 |
/// \return \c k if there are at least \c k arc-disjoint paths |
|
| 298 |
/// from \c s to \c t. Otherwise it returns the number of |
|
| 299 |
/// \return \c k if there are at least \c k arc-disjoint paths from |
|
| 300 |
/// \c s to \c t in the digraph. Otherwise it returns the number of |
|
| 299 | 301 |
/// arc-disjoint paths found. |
| 300 | 302 |
/// |
| 301 | 303 |
/// \note Apart from the return value, <tt>s.run(k)</tt> is just a |
| 302 | 304 |
/// shortcut of the following code. |
| 303 | 305 |
/// \code |
| 304 | 306 |
/// s.init(); |
| 305 | 307 |
/// s.findFlow(k); |
| 306 | 308 |
/// s.findPaths(); |
| 307 | 309 |
/// \endcode |
| 308 | 310 |
int run(int k = 2) {
|
| 309 | 311 |
init(); |
| 310 | 312 |
findFlow(k); |
| 311 | 313 |
findPaths(); |
| 312 | 314 |
return _path_num; |
| 313 | 315 |
} |
| 314 | 316 |
|
| 315 |
/// \brief |
|
| 317 |
/// \brief Initialize the algorithm. |
|
| 316 | 318 |
/// |
| 317 |
/// |
|
| 319 |
/// This function initializes the algorithm. |
|
| 318 | 320 |
void init() {
|
| 319 |
// |
|
| 321 |
// Initialize maps |
|
| 320 | 322 |
if (!_flow) {
|
| 321 | 323 |
_flow = new FlowMap(_graph); |
| 322 | 324 |
_local_flow = true; |
| 323 | 325 |
} |
| 324 | 326 |
if (!_potential) {
|
| 325 | 327 |
_potential = new PotentialMap(_graph); |
| 326 | 328 |
_local_potential = true; |
| 327 | 329 |
} |
| 328 | 330 |
for (ArcIt e(_graph); e != INVALID; ++e) (*_flow)[e] = 0; |
| 329 | 331 |
for (NodeIt n(_graph); n != INVALID; ++n) (*_potential)[n] = 0; |
| 330 | 332 |
|
| 331 | 333 |
_dijkstra = new ResidualDijkstra( _graph, *_flow, _length, |
| 332 | 334 |
*_potential, _pred, |
| 333 | 335 |
_source, _target ); |
| 334 | 336 |
} |
| 335 | 337 |
|
| 336 |
/// \brief |
|
| 338 |
/// \brief Execute the successive shortest path algorithm to find |
|
| 337 | 339 |
/// an optimal flow. |
| 338 | 340 |
/// |
| 339 |
/// Executes the successive shortest path algorithm to find a |
|
| 340 |
/// minimum cost flow, which is the union of \c k or less |
|
| 341 |
/// This function executes the successive shortest path algorithm to |
|
| 342 |
/// find a minimum cost flow, which is the union of \c k or less |
|
| 341 | 343 |
/// arc-disjoint paths. |
| 342 | 344 |
/// |
| 343 |
/// \return \c k if there are at least \c k arc-disjoint paths |
|
| 344 |
/// from \c s to \c t. Otherwise it returns the number of |
|
| 345 |
/// \return \c k if there are at least \c k arc-disjoint paths from |
|
| 346 |
/// \c s to \c t in the digraph. Otherwise it returns the number of |
|
| 345 | 347 |
/// arc-disjoint paths found. |
| 346 | 348 |
/// |
| 347 | 349 |
/// \pre \ref init() must be called before using this function. |
| 348 | 350 |
int findFlow(int k = 2) {
|
| 349 |
// |
|
| 351 |
// Find shortest paths |
|
| 350 | 352 |
_path_num = 0; |
| 351 | 353 |
while (_path_num < k) {
|
| 352 |
// |
|
| 354 |
// Run Dijkstra |
|
| 353 | 355 |
if (!_dijkstra->run()) break; |
| 354 | 356 |
++_path_num; |
| 355 | 357 |
|
| 356 |
// |
|
| 358 |
// Set the flow along the found shortest path |
|
| 357 | 359 |
Node u = _target; |
| 358 | 360 |
Arc e; |
| 359 | 361 |
while ((e = _pred[u]) != INVALID) {
|
| 360 | 362 |
if (u == _graph.target(e)) {
|
| 361 | 363 |
(*_flow)[e] = 1; |
| 362 | 364 |
u = _graph.source(e); |
| 363 | 365 |
} else {
|
| 364 | 366 |
(*_flow)[e] = 0; |
| 365 | 367 |
u = _graph.target(e); |
| 366 | 368 |
} |
| 367 | 369 |
} |
| 368 | 370 |
} |
| 369 | 371 |
return _path_num; |
| 370 | 372 |
} |
| 371 | 373 |
|
| 372 |
/// \brief |
|
| 374 |
/// \brief Compute the paths from the flow. |
|
| 373 | 375 |
/// |
| 374 |
/// |
|
| 376 |
/// This function computes the paths from the flow. |
|
| 375 | 377 |
/// |
| 376 | 378 |
/// \pre \ref init() and \ref findFlow() must be called before using |
| 377 | 379 |
/// this function. |
| 378 | 380 |
void findPaths() {
|
| 379 |
// Creating the residual flow map (the union of the paths not |
|
| 380 |
// found so far) |
|
| 381 |
// Create the residual flow map (the union of the paths not found |
|
| 382 |
// so far) |
|
| 381 | 383 |
FlowMap res_flow(_graph); |
| 382 |
for(ArcIt a(_graph);a!=INVALID;++a) res_flow[a]=(*_flow)[a]; |
|
| 384 |
for(ArcIt a(_graph); a != INVALID; ++a) res_flow[a] = (*_flow)[a]; |
|
| 383 | 385 |
|
| 384 | 386 |
paths.clear(); |
| 385 | 387 |
paths.resize(_path_num); |
| 386 | 388 |
for (int i = 0; i < _path_num; ++i) {
|
| 387 | 389 |
Node n = _source; |
| 388 | 390 |
while (n != _target) {
|
| 389 | 391 |
OutArcIt e(_graph, n); |
| 390 | 392 |
for ( ; res_flow[e] == 0; ++e) ; |
| 391 | 393 |
n = _graph.target(e); |
| 392 | 394 |
paths[i].addBack(e); |
| 393 | 395 |
res_flow[e] = 0; |
| 394 | 396 |
} |
| 395 | 397 |
} |
| 396 | 398 |
} |
| 397 | 399 |
|
| 398 | 400 |
/// @} |
| 399 | 401 |
|
| 400 | 402 |
/// \name Query Functions |
| 401 |
/// The |
|
| 403 |
/// The results of the algorithm can be obtained using these |
|
| 402 | 404 |
/// functions. |
| 403 | 405 |
/// \n The algorithm should be executed before using them. |
| 404 | 406 |
|
| 405 | 407 |
/// @{
|
| 406 | 408 |
|
| 407 |
/// \brief |
|
| 409 |
/// \brief Return a const reference to the arc map storing the |
|
| 408 | 410 |
/// found flow. |
| 409 | 411 |
/// |
| 410 |
/// Returns a const reference to the arc map storing the flow that |
|
| 411 |
/// is the union of the found arc-disjoint paths. |
|
| 412 |
/// This function returns a const reference to the arc map storing |
|
| 413 |
/// the flow that is the union of the found arc-disjoint paths. |
|
| 412 | 414 |
/// |
| 413 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 414 |
/// function. |
|
| 415 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 416 |
/// this function. |
|
| 415 | 417 |
const FlowMap& flowMap() const {
|
| 416 | 418 |
return *_flow; |
| 417 | 419 |
} |
| 418 | 420 |
|
| 419 |
/// \brief |
|
| 421 |
/// \brief Return a const reference to the node map storing the |
|
| 420 | 422 |
/// found potentials (the dual solution). |
| 421 | 423 |
/// |
| 422 |
/// Returns a const reference to the node map storing the found |
|
| 423 |
/// potentials that provide the dual solution of the underlying |
|
| 424 |
/// |
|
| 424 |
/// This function returns a const reference to the node map storing |
|
| 425 |
/// the found potentials that provide the dual solution of the |
|
| 426 |
/// underlying minimum cost flow problem. |
|
| 425 | 427 |
/// |
| 426 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 427 |
/// function. |
|
| 428 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 429 |
/// this function. |
|
| 428 | 430 |
const PotentialMap& potentialMap() const {
|
| 429 | 431 |
return *_potential; |
| 430 | 432 |
} |
| 431 | 433 |
|
| 432 |
/// \brief |
|
| 434 |
/// \brief Return the flow on the given arc. |
|
| 433 | 435 |
/// |
| 434 |
/// |
|
| 436 |
/// This function returns the flow on the given arc. |
|
| 435 | 437 |
/// It is \c 1 if the arc is involved in one of the found paths, |
| 436 | 438 |
/// otherwise it is \c 0. |
| 437 | 439 |
/// |
| 438 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 439 |
/// function. |
|
| 440 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 441 |
/// this function. |
|
| 440 | 442 |
int flow(const Arc& arc) const {
|
| 441 | 443 |
return (*_flow)[arc]; |
| 442 | 444 |
} |
| 443 | 445 |
|
| 444 |
/// \brief |
|
| 446 |
/// \brief Return the potential of the given node. |
|
| 445 | 447 |
/// |
| 446 |
/// |
|
| 448 |
/// This function returns the potential of the given node. |
|
| 447 | 449 |
/// |
| 448 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 449 |
/// function. |
|
| 450 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 451 |
/// this function. |
|
| 450 | 452 |
Length potential(const Node& node) const {
|
| 451 | 453 |
return (*_potential)[node]; |
| 452 | 454 |
} |
| 453 | 455 |
|
| 454 |
/// \brief |
|
| 456 |
/// \brief Return the total length (cost) of the found paths (flow). |
|
| 455 | 457 |
/// |
| 456 |
/// Returns the total length (cost) of the found paths (flow). |
|
| 457 |
/// The complexity of the function is \f$ O(e) \f$. |
|
| 458 |
/// This function returns the total length (cost) of the found paths |
|
| 459 |
/// (flow). The complexity of the function is \f$ O(e) \f$. |
|
| 458 | 460 |
/// |
| 459 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 460 |
/// function. |
|
| 461 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 462 |
/// this function. |
|
| 461 | 463 |
Length totalLength() const {
|
| 462 | 464 |
Length c = 0; |
| 463 | 465 |
for (ArcIt e(_graph); e != INVALID; ++e) |
| 464 | 466 |
c += (*_flow)[e] * _length[e]; |
| 465 | 467 |
return c; |
| 466 | 468 |
} |
| 467 | 469 |
|
| 468 |
/// \brief |
|
| 470 |
/// \brief Return the number of the found paths. |
|
| 469 | 471 |
/// |
| 470 |
/// |
|
| 472 |
/// This function returns the number of the found paths. |
|
| 471 | 473 |
/// |
| 472 |
/// \pre \ref run() or findFlow() must be called before using this |
|
| 473 |
/// function. |
|
| 474 |
/// \pre \ref run() or \ref findFlow() must be called before using |
|
| 475 |
/// this function. |
|
| 474 | 476 |
int pathNum() const {
|
| 475 | 477 |
return _path_num; |
| 476 | 478 |
} |
| 477 | 479 |
|
| 478 |
/// \brief |
|
| 480 |
/// \brief Return a const reference to the specified path. |
|
| 479 | 481 |
/// |
| 480 |
/// |
|
| 482 |
/// This function returns a const reference to the specified path. |
|
| 481 | 483 |
/// |
| 482 | 484 |
/// \param i The function returns the \c i-th path. |
| 483 | 485 |
/// \c i must be between \c 0 and <tt>%pathNum()-1</tt>. |
| 484 | 486 |
/// |
| 485 |
/// \pre \ref run() or findPaths() must be called before using this |
|
| 486 |
/// function. |
|
| 487 |
/// \pre \ref run() or \ref findPaths() must be called before using |
|
| 488 |
/// this function. |
|
| 487 | 489 |
Path path(int i) const {
|
| 488 | 490 |
return paths[i]; |
| 489 | 491 |
} |
| 490 | 492 |
|
| 491 | 493 |
/// @} |
| 492 | 494 |
|
| 493 | 495 |
}; //class Suurballe |
| 494 | 496 |
|
| 495 | 497 |
///@} |
| 496 | 498 |
|
| 497 | 499 |
} //namespace lemon |
| 498 | 500 |
| ... | ... |
@@ -19,138 +19,138 @@ |
| 19 | 19 |
#include <iostream> |
| 20 | 20 |
#include <fstream> |
| 21 | 21 |
|
| 22 | 22 |
#include <lemon/list_graph.h> |
| 23 | 23 |
#include <lemon/lgf_reader.h> |
| 24 | 24 |
#include <lemon/path.h> |
| 25 | 25 |
#include <lemon/suurballe.h> |
| 26 | 26 |
|
| 27 | 27 |
#include "test_tools.h" |
| 28 | 28 |
|
| 29 | 29 |
using namespace lemon; |
| 30 | 30 |
|
| 31 |
// |
|
| 31 |
// Check the feasibility of the flow |
|
| 32 | 32 |
template <typename Digraph, typename FlowMap> |
| 33 | 33 |
bool checkFlow( const Digraph& gr, const FlowMap& flow, |
| 34 | 34 |
typename Digraph::Node s, typename Digraph::Node t, |
| 35 | 35 |
int value ) |
| 36 | 36 |
{
|
| 37 | 37 |
TEMPLATE_DIGRAPH_TYPEDEFS(Digraph); |
| 38 | 38 |
for (ArcIt e(gr); e != INVALID; ++e) |
| 39 | 39 |
if (!(flow[e] == 0 || flow[e] == 1)) return false; |
| 40 | 40 |
|
| 41 | 41 |
for (NodeIt n(gr); n != INVALID; ++n) {
|
| 42 | 42 |
int sum = 0; |
| 43 | 43 |
for (OutArcIt e(gr, n); e != INVALID; ++e) |
| 44 | 44 |
sum += flow[e]; |
| 45 | 45 |
for (InArcIt e(gr, n); e != INVALID; ++e) |
| 46 | 46 |
sum -= flow[e]; |
| 47 | 47 |
if (n == s && sum != value) return false; |
| 48 | 48 |
if (n == t && sum != -value) return false; |
| 49 | 49 |
if (n != s && n != t && sum != 0) return false; |
| 50 | 50 |
} |
| 51 | 51 |
|
| 52 | 52 |
return true; |
| 53 | 53 |
} |
| 54 | 54 |
|
| 55 |
// |
|
| 55 |
// Check the optimalitiy of the flow |
|
| 56 | 56 |
template < typename Digraph, typename CostMap, |
| 57 | 57 |
typename FlowMap, typename PotentialMap > |
| 58 | 58 |
bool checkOptimality( const Digraph& gr, const CostMap& cost, |
| 59 | 59 |
const FlowMap& flow, const PotentialMap& pi ) |
| 60 | 60 |
{
|
| 61 |
// |
|
| 61 |
// Check the "Complementary Slackness" optimality condition |
|
| 62 | 62 |
TEMPLATE_DIGRAPH_TYPEDEFS(Digraph); |
| 63 | 63 |
bool opt = true; |
| 64 | 64 |
for (ArcIt e(gr); e != INVALID; ++e) {
|
| 65 | 65 |
typename CostMap::Value red_cost = |
| 66 | 66 |
cost[e] + pi[gr.source(e)] - pi[gr.target(e)]; |
| 67 | 67 |
opt = (flow[e] == 0 && red_cost >= 0) || |
| 68 | 68 |
(flow[e] == 1 && red_cost <= 0); |
| 69 | 69 |
if (!opt) break; |
| 70 | 70 |
} |
| 71 | 71 |
return opt; |
| 72 | 72 |
} |
| 73 | 73 |
|
| 74 |
// Checks a path |
|
| 75 |
template < typename Digraph, typename Path > |
|
| 74 |
// Check a path |
|
| 75 |
template <typename Digraph, typename Path> |
|
| 76 | 76 |
bool checkPath( const Digraph& gr, const Path& path, |
| 77 | 77 |
typename Digraph::Node s, typename Digraph::Node t) |
| 78 | 78 |
{
|
| 79 |
// |
|
| 79 |
// Check the "Complementary Slackness" optimality condition |
|
| 80 | 80 |
TEMPLATE_DIGRAPH_TYPEDEFS(Digraph); |
| 81 | 81 |
Node n = s; |
| 82 | 82 |
for (int i = 0; i < path.length(); ++i) {
|
| 83 | 83 |
if (gr.source(path.nth(i)) != n) return false; |
| 84 | 84 |
n = gr.target(path.nth(i)); |
| 85 | 85 |
} |
| 86 | 86 |
return n == t; |
| 87 | 87 |
} |
| 88 | 88 |
|
| 89 | 89 |
|
| 90 | 90 |
int main() |
| 91 | 91 |
{
|
| 92 | 92 |
DIGRAPH_TYPEDEFS(ListDigraph); |
| 93 | 93 |
|
| 94 |
// |
|
| 94 |
// Read the test digraph |
|
| 95 | 95 |
ListDigraph digraph; |
| 96 | 96 |
ListDigraph::ArcMap<int> length(digraph); |
| 97 | 97 |
Node source, target; |
| 98 | 98 |
|
| 99 | 99 |
std::string fname; |
| 100 | 100 |
if(getenv("srcdir"))
|
| 101 | 101 |
fname = std::string(getenv("srcdir"));
|
| 102 | 102 |
else fname = "."; |
| 103 | 103 |
fname += "/test/min_cost_flow_test.lgf"; |
| 104 | 104 |
|
| 105 | 105 |
std::ifstream input(fname.c_str()); |
| 106 | 106 |
check(input, "Input file '" << fname << "' not found"); |
| 107 | 107 |
DigraphReader<ListDigraph>(digraph, input). |
| 108 | 108 |
arcMap("cost", length).
|
| 109 | 109 |
node("source", source).
|
| 110 | 110 |
node("target", target).
|
| 111 | 111 |
run(); |
| 112 | 112 |
input.close(); |
| 113 | 113 |
|
| 114 |
// |
|
| 114 |
// Find 2 paths |
|
| 115 | 115 |
{
|
| 116 | 116 |
Suurballe<ListDigraph> suurballe(digraph, length, source, target); |
| 117 | 117 |
check(suurballe.run(2) == 2, "Wrong number of paths"); |
| 118 | 118 |
check(checkFlow(digraph, suurballe.flowMap(), source, target, 2), |
| 119 | 119 |
"The flow is not feasible"); |
| 120 | 120 |
check(suurballe.totalLength() == 510, "The flow is not optimal"); |
| 121 | 121 |
check(checkOptimality(digraph, length, suurballe.flowMap(), |
| 122 | 122 |
suurballe.potentialMap()), |
| 123 | 123 |
"Wrong potentials"); |
| 124 | 124 |
for (int i = 0; i < suurballe.pathNum(); ++i) |
| 125 | 125 |
check(checkPath(digraph, suurballe.path(i), source, target), |
| 126 | 126 |
"Wrong path"); |
| 127 | 127 |
} |
| 128 | 128 |
|
| 129 |
// |
|
| 129 |
// Find 3 paths |
|
| 130 | 130 |
{
|
| 131 | 131 |
Suurballe<ListDigraph> suurballe(digraph, length, source, target); |
| 132 | 132 |
check(suurballe.run(3) == 3, "Wrong number of paths"); |
| 133 | 133 |
check(checkFlow(digraph, suurballe.flowMap(), source, target, 3), |
| 134 | 134 |
"The flow is not feasible"); |
| 135 | 135 |
check(suurballe.totalLength() == 1040, "The flow is not optimal"); |
| 136 | 136 |
check(checkOptimality(digraph, length, suurballe.flowMap(), |
| 137 | 137 |
suurballe.potentialMap()), |
| 138 | 138 |
"Wrong potentials"); |
| 139 | 139 |
for (int i = 0; i < suurballe.pathNum(); ++i) |
| 140 | 140 |
check(checkPath(digraph, suurballe.path(i), source, target), |
| 141 | 141 |
"Wrong path"); |
| 142 | 142 |
} |
| 143 | 143 |
|
| 144 |
// |
|
| 144 |
// Find 5 paths (only 3 can be found) |
|
| 145 | 145 |
{
|
| 146 | 146 |
Suurballe<ListDigraph> suurballe(digraph, length, source, target); |
| 147 | 147 |
check(suurballe.run(5) == 3, "Wrong number of paths"); |
| 148 | 148 |
check(checkFlow(digraph, suurballe.flowMap(), source, target, 3), |
| 149 | 149 |
"The flow is not feasible"); |
| 150 | 150 |
check(suurballe.totalLength() == 1040, "The flow is not optimal"); |
| 151 | 151 |
check(checkOptimality(digraph, length, suurballe.flowMap(), |
| 152 | 152 |
suurballe.potentialMap()), |
| 153 | 153 |
"Wrong potentials"); |
| 154 | 154 |
for (int i = 0; i < suurballe.pathNum(); ++i) |
| 155 | 155 |
check(checkPath(digraph, suurballe.path(i), source, target), |
| 156 | 156 |
"Wrong path"); |
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