public:
int id, occupied;
scalar_t length, work_length;
- Vertex *terminal_vertex;
+ Vertex *origin_vertex, *terminal_vertex;
+
+ // These are the links in the origin_vertex leaving edge list
Edge *next, *pred;
+
+ inline void revert();
};
class Vertex {
int id, iteration;
Edge *root_edge;
scalar_t distance_from_source;
- Vertex *pred_vertex;
- Edge *pred_edge;
+ Edge *best_pred_edge_to_source;
- Vertex() { root_edge = 0; }
+ Vertex();
+ inline void add_edge(Edge *e);
+ inline void del_edge(Edge *e);
+};
- inline void add_edge(Edge *e) {
- e->next = root_edge;
- e->pred = 0;
- if(root_edge) { root_edge->pred = e; }
- root_edge = e;
- }
+//////////////////////////////////////////////////////////////////////
- inline void del_edge(Edge *e) {
- if(e == root_edge) { root_edge = e->next; }
- if(e->pred) { e->pred->next = e->next; }
- if(e->next) { e->next->pred = e->pred; }
- }
-};
+void Edge::revert() {
+ length = - length;
+ work_length = 0;
+ origin_vertex->del_edge(this);
+ terminal_vertex->add_edge(this);
+ Vertex *t = terminal_vertex;
+ terminal_vertex = origin_vertex;
+ origin_vertex = t;
+}
+
+//////////////////////////////////////////////////////////////////////
+
+Vertex::Vertex() {
+ root_edge = 0;
+}
+
+void Vertex::add_edge(Edge *e) {
+ e->next = root_edge;
+ e->pred = 0;
+ if(root_edge) { root_edge->pred = e; }
+ root_edge = e;
+}
+
+void Vertex::del_edge(Edge *e) {
+ if(e == root_edge) { root_edge = e->next; }
+ if(e->pred) { e->pred->next = e->next; }
+ if(e->next) { e->next->pred = e->pred; }
+}
+
+//////////////////////////////////////////////////////////////////////
void MTPGraph::print() {
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- cout << n << " -> " << e->terminal_vertex->id << " " << e->length;
- if(e->occupied) {
- cout << " *";
- }
- cout << endl;
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ cout << e->origin_vertex->id
+ << " -> "
+ << e->terminal_vertex->id
+ << " "
+ << e->length;
+ if(e->occupied) {
+ cout << " *";
}
+ cout << endl;
}
}
void MTPGraph::print_dot() {
cout << "digraph {" << endl;
cout << " node[shape=circle];" << endl;
- for(int n = 0; n < _nb_vertices; n++) {
- int a = vertices[n].id;
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- int b = e->terminal_vertex->id;
- if(e->occupied) {
- cout << " " << b << " -> " << a << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
- } else {
- cout << " " << a << " -> " << b << " [color=gray,label=\"" << e->length << "\"];" << endl;
- }
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ if(e->occupied) {
+ cout << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
+ } else {
+ cout << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ << " [color=gray,label=\"" << e->length << "\"];" << endl;
}
}
cout << "}" << endl;
MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
int *from, int *to,
- int src, int snk) {
+ int source, int sink) {
_nb_vertices = nb_vertices;
_nb_edges = nb_edges;
- edges = new Edge[_nb_edges];
- vertices = new Vertex[_nb_vertices];
+ _edges = new Edge[_nb_edges];
+ _vertices = new Vertex[_nb_vertices];
_front = new Vertex *[_nb_vertices];
_new_front = new Vertex *[_nb_vertices];
- _source = &vertices[src];
- _sink = &vertices[snk];
+ _source = &_vertices[source];
+ _sink = &_vertices[sink];
for(int v = 0; v < _nb_vertices; v++) {
- vertices[v].id = v;
+ _vertices[v].id = v;
}
for(int e = 0; e < nb_edges; e++) {
- vertices[from[e]].add_edge(&edges[e]);
- edges[e].occupied = 0;
- edges[e].id = e;
- edges[e].terminal_vertex = &vertices[to[e]];
+ _vertices[from[e]].add_edge(_edges + e);
+ _edges[e].occupied = 0;
+ _edges[e].id = e;
+ _edges[e].origin_vertex = _vertices + from[e];
+ _edges[e].terminal_vertex = _vertices + to[e];
}
}
MTPGraph::~MTPGraph() {
- delete[] vertices;
- delete[] edges;
+ delete[] _vertices;
+ delete[] _edges;
delete[] _front;
delete[] _new_front;
}
-void MTPGraph::initialize_work_lengths() {
+void MTPGraph::initialize_work_lengths_with_min() {
scalar_t length_min = 0;
for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+ for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
length_min = min(e->length, length_min);
}
}
for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+ for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
e->work_length = e->length - length_min;
}
}
}
void MTPGraph::update_work_lengths() {
- for(int n = 0; n < _nb_vertices; n++) {
- scalar_t d = vertices[n].distance_from_source;
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
- e->work_length += d - e->terminal_vertex->distance_from_source;
- }
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ e->work_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
}
}
scalar_t residual_error = 0.0;
#endif
for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+ for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
if(e->work_length < 0) {
#ifdef VERBOSE
residual_error -= e->work_length;
#endif
}
+// This method does not change the edge occupation. It update
+// distance_from_source and best_pred_edge_to_source.
void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
Vertex **tmp_front;
int tmp_front_size;
scalar_t d;
for(int v = 0; v < _nb_vertices; v++) {
- vertices[v].distance_from_source = FLT_MAX;
- vertices[v].pred_vertex = 0;
- vertices[v].pred_edge = 0;
- vertices[v].iteration = 0;
+ _vertices[v].distance_from_source = FLT_MAX;
+ _vertices[v].best_pred_edge_to_source = 0;
+ _vertices[v].iteration = 0;
}
int iteration = 0;
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
- tv->pred_vertex = v;
- tv->pred_edge = e;
+ tv->best_pred_edge_to_source = e;
if(tv->iteration < iteration) {
_new_front[_new_front_size++] = tv;
tv->iteration = iteration;
void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
scalar_t total_length;
+ Vertex *v;
+ Edge *e;
for(int e = 0; e < _nb_edges; e++) {
- edges[e].length = lengths[e];
- edges[e].work_length = edges[e].length;
+ _edges[e].length = lengths[e];
+ _edges[e].work_length = _edges[e].length;
}
+ // We use one iteration of find_shortest_path simply to propagate
+ // the distance to make all the edge lengths positive.
find_shortest_path(_front, _new_front);
update_work_lengths();
- // initialize_work_lengths();
+ // #warning
+ // initialize_work_lengths_with_min();
do {
force_positive_work_lengths();
total_length = 0.0;
// Do we reach the _sink?
- if(_sink->pred_edge) {
-
+ if(_sink->best_pred_edge_to_source) {
// If yes, compute the length of the best path
- for(Vertex *v = _sink; v->pred_edge; v = v->pred_vertex) {
- total_length += v->pred_edge->length;
+ v = _sink;
+ while(v->best_pred_edge_to_source) {
+ total_length += v->best_pred_edge_to_source->length;
+ v = v->best_pred_edge_to_source->origin_vertex;
}
-
// If that length is negative
if(total_length < 0.0) {
+#ifdef VERBOSE
+ cout << "Found a path of length " << total_length << endl;
+#endif
// Invert all the edges along the best path
- for(Vertex *v = _sink; v->pred_edge; v = v->pred_vertex) {
- Edge *e = v->pred_edge;
- e->terminal_vertex = v->pred_vertex;
+ v = _sink;
+ while(v->best_pred_edge_to_source) {
+ e = v->best_pred_edge_to_source;
+ v = e->origin_vertex;
+ e->revert();
e->occupied = 1 - e->occupied;
- e->length = - e->length;
- e->work_length = - e->work_length;
- v->pred_vertex->del_edge(e);
- v->add_edge(e);
}
}
}
} while(total_length < 0.0);
- for(Edge *e = _sink->root_edge; e; e = e->next) {
- if(e->occupied) {
- Edge *f = e;
- cout << "PATH " << _sink->id;
- while(f) {
- cout << " " << f->terminal_vertex->id;
- for(f = f->terminal_vertex->root_edge; f && !f->occupied; f = f->next);
- }
- cout << endl;
- }
- }
-
- for(int n = 0; n < _nb_vertices; n++) {
- Vertex *v = &vertices[n];
- for(Edge *e = v->root_edge; e; e = e->next) {
- result_edge_occupation[e->id] = e->occupied;
- }
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ if(e->occupied) { e->revert(); }
+ result_edge_occupation[k] = e->occupied;
}
}
projects / mtp.git / blobdiff