#include <iostream>
#include <float.h>
+#include <stdlib.h>
using namespace std;
class Edge {
public:
int id, occupied;
- scalar_t length, work_length;
+ scalar_t length, positivized_length;
Vertex *origin_vertex, *terminal_vertex;
- Edge *next, *pred;
+
+ // These are the links in the origin_vertex leaving edge list
+ Edge *next_leaving_edge, *pred_leaving_edge;
+
+ inline void revert();
};
class Vertex {
public:
- int id, iteration;
- Edge *root_edge;
+ int id;
+ Edge *leaving_edges;
scalar_t distance_from_source;
- Vertex *pred_vertex;
- Edge *pred_edge;
+ Edge *best_pred_edge_to_source;
- Vertex() { root_edge = 0; }
+ int iteration; // Used in find_shortest_path to know if we already
+ // added this vertex to the front
+ 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;
+ positivized_length = 0;
+ origin_vertex->del_edge(this);
+ terminal_vertex->add_edge(this);
+ Vertex *t = terminal_vertex;
+ terminal_vertex = origin_vertex;
+ origin_vertex = t;
+}
-void MTPGraph::print() {
- 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;
- }
+//////////////////////////////////////////////////////////////////////
+
+Vertex::Vertex() {
+ leaving_edges = 0;
}
-void MTPGraph::print_dot() {
- cout << "digraph {" << endl;
- cout << " node[shape=circle];" << 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;
+void Vertex::add_edge(Edge *e) {
+ e->next_leaving_edge = leaving_edges;
+ e->pred_leaving_edge = 0;
+ if(leaving_edges) { leaving_edges->pred_leaving_edge = e; }
+ leaving_edges = e;
+}
+
+void Vertex::del_edge(Edge *e) {
+ if(e == leaving_edges) { leaving_edges = e->next_leaving_edge; }
+ if(e->pred_leaving_edge) { e->pred_leaving_edge->next_leaving_edge = e->next_leaving_edge; }
+ if(e->next_leaving_edge) { e->next_leaving_edge->pred_leaving_edge = e->pred_leaving_edge; }
+}
+
+//////////////////////////////////////////////////////////////////////
+
+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 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].origin_vertex = &vertices[from[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];
}
+ paths = 0;
+ nb_paths = 0;
}
MTPGraph::~MTPGraph() {
- delete[] vertices;
- delete[] edges;
+ delete[] _vertices;
+ delete[] _edges;
delete[] _front;
delete[] _new_front;
+ for(int p = 0; p < nb_paths; p++) delete paths[p];
+ delete[] paths;
+}
+
+//////////////////////////////////////////////////////////////////////
+
+void MTPGraph::print(ostream *os) {
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ (*os) << e->origin_vertex->id
+ << " -> "
+ << e->terminal_vertex->id
+ << " "
+ << e->length;
+ if(e->occupied) {
+ (*os) << " *";
+ }
+ (*os) << endl;
+ }
+}
+
+void MTPGraph::print_dot(ostream *os) {
+ (*os) << "digraph {" << endl;
+ (*os) << " node[shape=circle];" << 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
+ << " [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) << "}" << endl;
}
-void MTPGraph::initialize_work_lengths() {
+//////////////////////////////////////////////////////////////////////
+
+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].root_edge; e; e = e->next) {
+ 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].root_edge; e; e = e->next) {
- e->work_length = e->length - length_min;
+ for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
+ e->positivized_length = e->length - length_min;
}
}
}
-void MTPGraph::update_work_lengths() {
+void MTPGraph::update_positivized_lengths() {
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;
+ Edge *e = _edges + k;
+ e->positivized_length +=
+ e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
}
}
-void MTPGraph::force_positive_work_lengths() {
+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].root_edge; e; e = e->next) {
- if(e->work_length < 0) {
+ for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->positivized_length < 0) {
#ifdef VERBOSE
- residual_error -= e->work_length;
+ residual_error -= e->positivized_length;
+ max_error = max(max_error, fabs(e->positivized_length));
#endif
- e->work_length = 0.0;
+ 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) {
Vertex **tmp_front;
int tmp_front_size;
Vertex *v, *tv;
+ Edge *e;
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;
do {
_new_front_size = 0;
iteration++;
+
+ // for(int k = 0; k < _nb_edges; k++) {
+ // Edge *e = _edges + k;
+ // d = e->origin_vertex->distance_from_source + e->positivized_length;
+ // if(d < e->terminal_vertex->distance_from_source) {
+ // e->terminal_vertex->distance_from_source = d;
+ // _new_front_size++;
+ // }
+ // }
+
+ // for(int n = 0; n < _nb_vertices; n++) {
+ // v = &_vertices[n];
+ // for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ // d = v->distance_from_source + e->positivized_length;
+ // tv = e->terminal_vertex;
+ // if(d < tv->distance_from_source) {
+ // tv->distance_from_source = d;
+ // tv->best_pred_edge_to_source = e;
+ // if(tv->iteration < iteration) {
+ // _new_front[_new_front_size++] = tv;
+ // tv->iteration = iteration;
+ // }
+ // }
+ // }
+ // }
+
for(int f = 0; f < _front_size; f++) {
v = _front[f];
- for(Edge *e = v->root_edge; e; e = e->next) {
- d = v->distance_from_source + e->work_length;
+ for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ d = v->distance_from_source + e->positivized_length;
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;
_new_front_size = _front_size;
_front_size = tmp_front_size;
} while(_front_size > 0);
+
+#ifdef VERBOSE
+ scalar_t min_delta = 0, delta;
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+ // d = e->origin_vertex->distance_from_source + e->positivized_length;
+ // if(d > e->terminal_vertex->distance_from_source) { abort(); }
+ delta = e->positivized_length +
+ (e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source);
+ min_delta = min(delta, min_delta);
+ }
+ cout << "min_delta = " << delta << endl;
+#endif
}
-void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
+void MTPGraph::find_best_paths(scalar_t *lengths) {
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].occupied = 0;
+ _edges[e].positivized_length = _edges[e].length;
}
-#warning
- // find_shortest_path(_front, _new_front);
- // update_work_lengths();
+ // 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_positivized_lengths();
- initialize_work_lengths();
+ // #warning
+ // initialize_positivized_lengths_with_min();
do {
- force_positive_work_lengths();
+ force_positivized_lengths();
find_shortest_path(_front, _new_front);
- update_work_lengths();
+ update_positivized_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_vertex; 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;
+ cerr << "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;
+ v = _sink;
+ while(v->best_pred_edge_to_source) {
+ e = v->best_pred_edge_to_source;
+ v = e->origin_vertex;
+ e->revert();
+ // This is the only place where we change the occupations of
+ // edges
e->occupied = 1 - e->occupied;
- e->length = - e->length;
- e->work_length = - e->work_length;
- e->origin_vertex->del_edge(e);
- e->terminal_vertex->add_edge(e);
- Vertex *t = e->terminal_vertex;
- e->terminal_vertex = e->origin_vertex;
- e->origin_vertex = t;
}
}
}
} while(total_length < 0.0);
for(int k = 0; k < _nb_edges; k++) {
- Edge *e = edges + k;
- if(e->occupied) {
- e->length = - e->length;
- e->work_length = 0;
- e->origin_vertex->del_edge(e);
- e->terminal_vertex->add_edge(e);
- Vertex *t = e->terminal_vertex;
- e->terminal_vertex = e->origin_vertex;
- e->origin_vertex = t;
+ Edge *e = _edges + k;
+ if(e->occupied) { e->revert(); }
+ }
+}
+
+int MTPGraph::retrieve_one_path(Edge *e, int *nodes) {
+ Edge *f, *next = 0;
+ int l = 0;
+
+ if(nodes) { nodes[l++] = e->origin_vertex->id; }
+ else l++;
+
+ while(e->terminal_vertex != _sink) {
+ if(nodes) { nodes[l++] = e->terminal_vertex->id; }
+ else l++;
+ int nb_choices = 0;
+ 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;
+ abort();
+ }
+ if(nb_choices > 1) {
+ cerr << "Non node-disjoint path, can not retrieve." << endl;
+ abort();
+ }
}
+ e = next;
}
- // 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;
- // }
- // }
+ if(nodes) { nodes[l++] = e->terminal_vertex->id; }
+ else l++;
- // int nb_occupied = 0;
- // for(int e = 0; e < _nb_edges; e++) {
- // for(int n = 0; n < _nb_vertices; n++) {
- // Vertex *v = &vertices[n];
- // for(Edge *e = v->root_edge; e; e = e->next) {
- // if(e->occupied) nb_occupied++;
- // }
- // }
- // }
+ return l;
+}
- 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;
+void MTPGraph::retrieve_disjoint_paths() {
+ Edge *e;
+
+ for(int p = 0; p < nb_paths; p++) delete paths[p];
+ delete[] paths;
+
+ nb_paths = 0;
+ for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->occupied) { nb_paths++; }
+ }
+
+ paths = new Path *[nb_paths];
+
+ int p = 0;
+ for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ if(e->occupied) {
+ int l = retrieve_one_path(e, 0);
+ paths[p] = new Path(l);
+ retrieve_one_path(e, paths[p]->nodes);
+ p++;
}
}
}
projects / mtp.git / blobdiff