#include "mtp_graph.h"
+#include <cmath>
#include <float.h>
using namespace std;
class Vertex {
public:
- Edge *leaving_edges;
scalar_t distance_from_source;
Edge *pred_edge_toward_source;
+
+ Edge *leaving_edge_list_root;
Vertex **heap_slot;
Vertex();
//////////////////////////////////////////////////////////////////////
Vertex::Vertex() {
- leaving_edges = 0;
+ leaving_edge_list_root = 0;
}
void Vertex::add_leaving_edge(Edge *e) {
- e->next_leaving_edge = leaving_edges;
+ e->next_leaving_edge = leaving_edge_list_root;
e->pred_leaving_edge = 0;
- if(leaving_edges) { leaving_edges->pred_leaving_edge = e; }
- leaving_edges = e;
+ if(leaving_edge_list_root) {
+ leaving_edge_list_root->pred_leaving_edge = e;
+ }
+ leaving_edge_list_root = e;
}
void Vertex::del_leaving_edge(Edge *e) {
- if(e == leaving_edges) {
- leaving_edges = e->next_leaving_edge;
+ if(e == leaving_edge_list_root) {
+ leaving_edge_list_root = e->next_leaving_edge;
}
if(e->pred_leaving_edge) {
e->pred_leaving_edge->next_leaving_edge = e->next_leaving_edge;
//////////////////////////////////////////////////////////////////////
-static int compare_vertex(const void *v1, const void *v2) {
+static int compare_vertices_on_distance(const void *v1, const void *v2) {
scalar_t delta =
(*((Vertex **) v1))->distance_from_source -
(*((Vertex **) v2))->distance_from_source;
else return 0;
}
+//////////////////////////////////////////////////////////////////////
+
MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
int *vertex_from, int *vertex_to,
int source, int sink) {
paths = 0;
nb_paths = 0;
- if(compute_dp_ranks()) {
- // Here the distance_from_source field of every vertex is the
- // number of DP iterations needed to update it. Hence we only have
- // to process the vertex in that order.
- for(int v = 0; v < _nb_vertices; v++) { _dp_order[v] = &_vertices[v]; }
- qsort(_dp_order, _nb_vertices, sizeof(Vertex *), compare_vertex);
- } else {
- cerr << __FILE__ << ": This graph is not a DAG." << endl;
- abort();
- }
+ compute_dp_ranks();
+ for(int v = 0; v < _nb_vertices; v++) { _dp_order[v] = &_vertices[v]; }
+ qsort(_dp_order, _nb_vertices, sizeof(Vertex *), compare_vertices_on_distance);
}
MTPGraph::~MTPGraph() {
delete[] paths;
}
-int MTPGraph::compute_dp_ranks() {
+//////////////////////////////////////////////////////////////////////
+
+void MTPGraph::compute_dp_ranks() {
Vertex *v;
Edge *e;
// rank of a node is the iteration at which is it removed, and we
// set the distance_from_source fields to this value.
- Vertex **unreached = new Vertex *[_nb_vertices];
+ Vertex **with_predecessor = new Vertex *[_nb_vertices];
- // All the nodes are unreached at first
+ // All the nodes are with_predecessor at first
for(int k = 0; k < _nb_vertices; k++) {
_vertices[k].distance_from_source = 0;
- unreached[k] = &_vertices[k];
+ with_predecessor[k] = &_vertices[k];
}
scalar_t rank = 1;
- int nb_unreached = _nb_vertices, pred_nb_unreached;
+ int nb_with_predecessor = _nb_vertices, pred_nb_with_predecessor;
do {
// We set the distance_from_source field of all the vertices with incoming
// edges to the current rank value
- for(int f = 0; f < nb_unreached; f++) {
- v = unreached[f];
- for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ for(int f = 0; f < nb_with_predecessor; f++) {
+ v = with_predecessor[f];
+ for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
e->terminal_vertex->distance_from_source = rank;
}
}
- pred_nb_unreached = nb_unreached;
- nb_unreached = 0;
+ pred_nb_with_predecessor = nb_with_predecessor;
+ nb_with_predecessor = 0;
// We keep all the vertices with incoming nodes
- for(int f = 0; f < pred_nb_unreached; f++) {
- v = unreached[f];
+ for(int f = 0; f < pred_nb_with_predecessor; f++) {
+ v = with_predecessor[f];
if(v->distance_from_source == rank) {
- unreached[nb_unreached++] = v;
+ with_predecessor[nb_with_predecessor++] = v;
}
}
rank++;
- } while(nb_unreached < pred_nb_unreached);
+ } while(nb_with_predecessor < pred_nb_with_predecessor);
- delete[] unreached;
+ delete[] with_predecessor;
- return nb_unreached == 0;
+ if(nb_with_predecessor > 0) {
+ cerr << __FILE__ << ": The graph is not a DAG." << endl;
+ abort();
+ }
}
//////////////////////////////////////////////////////////////////////
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
(*os) << e->origin_vertex - _vertices
- << " -> "
- << e->terminal_vertex - _vertices
- << " "
- << e->length;
- if(e->occupied) {
- (*os) << " *";
- }
+ << " -> "
+ << e->terminal_vertex - _vertices
+ << " (" << e->length << ")";
+ if(e->occupied) { (*os) << " *"; }
(*os) << endl;
}
}
Edge *e = _edges + k;
if(e->positivized_length < 0) {
-
#ifdef VERBOSE
residual_error -= e->positivized_length;
max_error = max(max_error, - e->positivized_length);
for(int k = 0; k < _nb_vertices; k++) {
v = _dp_order[k];
- for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ for(e = v->leaving_edge_list_root; 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_edge_toward_source = e;
- tv->decrease_distance_in_heap(_heap);
}
}
}
// pred_edge_toward_source.
void MTPGraph::find_shortest_path() {
- Vertex *v, *tv, **a, **b;
+ Vertex *v, *tv, **last_slot;
Edge *e;
scalar_t d;
// Get the closest to the source
v = _heap[0];
- // Remove it from the heap (swap it with the last in the heap, and
+ // Remove it from the heap (swap it with the last_slot in the heap, and
// update the distance of that one)
_heap_size--;
- a = _heap;
- b = _heap + _heap_size;
- swap(*a, *b); swap((*a)->heap_slot, (*b)->heap_slot);
+ last_slot = _heap + _heap_size;
+ swap(*_heap, *last_slot); swap((*_heap)->heap_slot, (*last_slot)->heap_slot);
_heap[0]->increase_distance_in_heap(_heap, _heap + _heap_size);
- // Now update the neighbors of the currently closest to the source
- for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ // Now update the neighbors of the node currently closest to the
+ // source
+ for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
d = v->distance_from_source + e->positivized_length;
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
_edges[e].positivized_length = _edges[e].length;
}
- // Compute the distance of every node from the source by just
+ // Compute the distance of all the nodes from the source by just
// visiting them in the proper DAG ordering we computed when
// building the graph
dp_compute_distances();
} else l++;
nb_occupied_next = 0;
- for(f = e->terminal_vertex->leaving_edges; f; f = f->next_leaving_edge) {
+ for(f = e->terminal_vertex->leaving_edge_list_root; f; f = f->next_leaving_edge) {
if(f->occupied) { nb_occupied_next++; next = f; }
}
delete[] paths;
nb_paths = 0;
- for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ for(e = _source->leaving_edge_list_root; e; e = e->next_leaving_edge) {
if(e->occupied) { nb_paths++; }
}
paths = new Path *[nb_paths];
p = 0;
- for(e = _source->leaving_edges; e; e = e->next_leaving_edge) {
+ for(e = _source->leaving_edge_list_root; e; e = e->next_leaving_edge) {
if(e->occupied) {
l = retrieve_one_path(e, 0);
paths[p] = new Path(l);