// These are the links in the origin_vertex leaving edge list
Edge *next_leaving_edge, *pred_leaving_edge;
- inline void revert();
+ inline void invert();
};
class Vertex {
int id;
Edge *leaving_edges;
scalar_t distance_from_source;
- Edge *best_pred_edge_to_source;
+ Edge *pred_edge_toward_source;
int iteration; // Used in find_shortest_path to know if we already
// added this vertex to the front
//////////////////////////////////////////////////////////////////////
-void Edge::revert() {
+void Edge::invert() {
length = - length;
positivized_length = 0;
origin_vertex->del_edge(this);
//////////////////////////////////////////////////////////////////////
-Path::Path(int l) {
- length = l;
- nodes = new int[length];
-}
-
-Path::~Path() {
- delete[] nodes;
-}
-
-//////////////////////////////////////////////////////////////////////
-
MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
int *from, int *to,
int source, int sink) {
void MTPGraph::print_dot(ostream *os) {
(*os) << "digraph {" << endl;
- (*os) << " node[shape=circle];" << endl;
+ // (*os) << " node [shape=circle];" << endl;
+ (*os) << " edge [color=gray]" << endl;
+ (*os) << " " << _source->id << " [peripheries=2];" << endl;
+ (*os) << " " << _sink->id << " [peripheries=2];" << endl;
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
+ // (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ // << ";"
+ // << endl;
if(e->occupied) {
- (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
<< " [style=bold,color=black,label=\"" << e->length << "\"];" << endl;
} else {
- (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- << " [color=gray,label=\"" << e->length << "\"];" << endl;
+ (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
+ << " [label=\"" << e->length << "\"];" << endl;
}
}
(*os) << "}" << endl;
//////////////////////////////////////////////////////////////////////
-void MTPGraph::initialize_positivized_lengths_with_min() {
- scalar_t length_min = 0;
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
- length_min = min(e->length, length_min);
- }
- }
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
- e->positivized_length = e->length - length_min;
- }
- }
-}
-
void MTPGraph::update_positivized_lengths() {
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- e->positivized_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
+ e->positivized_length +=
+ e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
}
}
void MTPGraph::force_positivized_lengths() {
#ifdef VERBOSE
scalar_t residual_error = 0.0;
+ scalar_t max_error = 0.0;
#endif
for(int n = 0; n < _nb_vertices; n++) {
for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
if(e->positivized_length < 0) {
#ifdef VERBOSE
residual_error -= e->positivized_length;
+ max_error = max(max_error, - e->positivized_length);
#endif
e->positivized_length = 0.0;
}
}
}
#ifdef VERBOSE
- cerr << "residual_error " << residual_error << endl;
+ cerr << "residual_error " << residual_error << " max_error " << residual_error << endl;
#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) {
+// distance_from_source and pred_edge_toward_source.
+void MTPGraph::find_shortest_path() {
Vertex **tmp_front;
int tmp_front_size;
Vertex *v, *tv;
for(int v = 0; v < _nb_vertices; v++) {
_vertices[v].distance_from_source = FLT_MAX;
- _vertices[v].best_pred_edge_to_source = 0;
+ _vertices[v].pred_edge_toward_source = 0;
_vertices[v].iteration = 0;
}
do {
_new_front_size = 0;
iteration++;
+
for(int f = 0; f < _front_size; f++) {
v = _front[f];
for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
- tv->best_pred_edge_to_source = e;
+ tv->pred_edge_toward_source = e;
if(tv->iteration < iteration) {
_new_front[_new_front_size++] = tv;
tv->iteration = iteration;
// 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);
+ find_shortest_path();
update_positivized_lengths();
- // #warning
- // initialize_positivized_lengths_with_min();
-
do {
force_positivized_lengths();
- find_shortest_path(_front, _new_front);
+ find_shortest_path();
update_positivized_lengths();
total_length = 0.0;
// Do we reach the _sink?
- if(_sink->best_pred_edge_to_source) {
+ if(_sink->pred_edge_toward_source) {
// If yes, compute the length of the best path
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;
+ while(v->pred_edge_toward_source) {
+ total_length += v->pred_edge_toward_source->length;
+ v = v->pred_edge_toward_source->origin_vertex;
}
// If that length is negative
if(total_length < 0.0) {
#endif
// Invert all the edges along the best path
v = _sink;
- while(v->best_pred_edge_to_source) {
- e = v->best_pred_edge_to_source;
+ while(v->pred_edge_toward_source) {
+ e = v->pred_edge_toward_source;
v = e->origin_vertex;
- e->revert();
+ e->invert();
// This is the only place where we change the occupations of
// edges
e->occupied = 1 - e->occupied;
} while(total_length < 0.0);
+ // Put back the graph in its original state (i.e. invert edges which
+ // have been inverted in the process)
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- if(e->occupied) { e->revert(); }
+ if(e->occupied) { e->invert(); }
}
}
int MTPGraph::retrieve_one_path(Edge *e, int *nodes) {
- Edge *f, *next;
+ Edge *f, *next = 0;
int l = 0;
if(nodes) { nodes[l++] = e->origin_vertex->id; }
for(f = e->terminal_vertex->leaving_edges; f; f = f->next_leaving_edge) {
if(f->occupied) { nb_choices++; next = f; }
if(nb_choices == 0) {
- cerr << "Non-sink path end point?!" << endl;
+ cerr << "retrieve_one_path: Non-sink end point." << endl;
abort();
}
if(nb_choices > 1) {
- cerr << "Non node-disjoint path, can not retrieve." << endl;
+ cerr << "retrieve_one_path: Non node-disjoint paths." << endl;
abort();
}
}
projects / mtp.git / blobdiff