+++ /dev/null
-
-///////////////////////////////////////////////////////////////////////////
-// START_IP_HEADER //
-// //
-// This program is free software: you can redistribute it and/or modify //
-// it under the terms of the version 3 of the GNU General Public License //
-// as published by the Free Software Foundation. //
-// //
-// This program is distributed in the hope that it will be useful, but //
-// WITHOUT ANY WARRANTY; without even the implied warranty of //
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU //
-// General Public License for more details. //
-// //
-// You should have received a copy of the GNU General Public License //
-// along with this program. If not, see <http://www.gnu.org/licenses/>. //
-// //
-// Written by and Copyright (C) Francois Fleuret //
-// Contact <francois.fleuret@idiap.ch> for comments & bug reports //
-// //
-// END_IP_HEADER //
-///////////////////////////////////////////////////////////////////////////
-
-// #define VERBOSE
-
-#include <iostream>
-#include <fstream>
-#include <cmath>
-#include <stdio.h>
-#include <stdlib.h>
-#include <float.h>
-
-using namespace std;
-
-typedef float scalar_t;
-
-#ifdef DEBUG
-#define ASSERT(x) if(!(x)) { \
- std::cerr << "ASSERT FAILED IN " << __FILE__ << ":" << __LINE__ << endl; \
- abort(); \
-}
-#else
-#define ASSERT(x)
-#endif
-
-// In all the code:
-//
-// * el[e] is the length of edge e
-// * ea[e] is its starting node
-// * eb[e] is its destination node.
-
-// Adds to all the edge length the length of the shortest (which can
-// be negative)
-void raise_es(int nb_edges, scalar_t *el) {
- scalar_t min_es = el[0];
- for(int e = 1; e < nb_edges; e++) {
- min_es = min(min_es, el[e]);
- }
- for(int e = 0; e < nb_edges; e++) {
- el[e] -= min_es;
- }
-}
-
-// Adds to every edge length the differential of the psi function on
-// it
-void add_dpsi_es(int nb_edges, scalar_t *el, int *ea, int *eb, scalar_t *psi) {
- for(int e = 0; e < nb_edges; e++) {
- el[e] += psi[ea[e]] - psi[eb[e]];
- }
-}
-
-// Finds the shortest path in the graph and returns in
-// result_edge_back, for each vertex, the edge to follow back from it
-// to reach the source with the shortest path, and in result_dist the
-// distance to the source. The edge lengths have to be positive.
-void find_shortest(int nb_vertices,
- int nb_edges, scalar_t *el, int *ea, int *eb,
- int source, int sink,
- int *result_edge_back, scalar_t *result_dist) {
- for(int v = 0; v < nb_vertices; v++) {
- result_dist[v] = FLT_MAX;
- result_edge_back[v] = -1;
- }
-
- result_dist[source] = 0;
-
-#ifdef DEBUG
- for(int e = 0; e < nb_edges; e++) {
- if(el[e] < 0) abort();
- }
-#endif
-
- int nb_changes;
- scalar_t d;
- do {
- nb_changes = 0;
- for(int e = 0; e < nb_edges; e++) {
- d = result_dist[ea[e]] + el[e];
- if(d < result_dist[eb[e]]) {
- nb_changes++;
- result_dist[eb[e]] = d;
- result_edge_back[eb[e]] = e;
- }
- }
- } while(nb_changes > 0);
-}
-
-// Iterates find_shortest as long as it finds paths of negative
-// lengths. Returns which edges are occupied by the superposition of
-// paths in result_edge_occupation.
-//
-// **WARNING** this routine changes the values of el, ea, and eb
-// (i.e. the occupied edges are inverted).
-void find_best_paths(int nb_vertices,
- int nb_edges, scalar_t *el, int *ea, int *eb,
- int source, int sink,
- int *result_edge_occupation) {
- scalar_t *dist = new scalar_t[nb_vertices];
- int *edge_back = new int[nb_vertices];
- scalar_t *positive_el = new scalar_t[nb_edges];
- scalar_t s;
- int v;
-
- for(int e = 0; e < nb_edges; e++) {
- positive_el[e] = el[e];
- result_edge_occupation[e] = 0;
- }
-
- raise_es(nb_edges, positive_el);
-
- do {
- find_shortest(nb_vertices, nb_edges, positive_el, ea, eb, source, sink, edge_back, dist);
- add_dpsi_es(nb_edges, positive_el, ea, eb, dist);
- s = 0.0;
-
- // If the new path reaches the sink, we will backtrack on it to
- // compute its score and invert edges
-
- if(edge_back[sink] >= 0) {
-
- v = sink;
- while(v != source) {
- int e = edge_back[v];
- ASSERT(eb[e] == v);
- v = ea[e];
- s += el[e];
- }
-
- // We found a good path (score < 0), we revert the edges along
- // the path and invert their occupation (since adding a path on
- // a path already occupied means removing flow on it)
-
- if(s < 0) {
- v = sink;
-#ifdef VERBOSE
- cout << "FOUND A PATH OF LENGTH " << s << endl;
-#endif
- while(v != source) {
- int e = edge_back[v];
- ASSERT(eb[e] == v);
- v = ea[e];
-#ifdef VERBOSE
- cout << "INVERTING " << ea[e] << " -> " << eb[e] << " [" << el[e] << "]" << endl;
-#endif
- int k = eb[e];
- eb[e] = ea[e];
- ea[e] = k;
- positive_el[e] = - positive_el[e];
- el[e] = - el[e];
- result_edge_occupation[e] = 1 - result_edge_occupation[e];
- }
- }
- }
- } while(s < 0);
-
- delete[] positive_el;
- delete[] dist;
- delete[] edge_back;
-}
-
-int main(int argc, char **argv) {
-
- if(argc < 2) {
- cerr << argv[0] << " <graph file>" << endl;
- exit(EXIT_FAILURE);
- }
-
- ifstream *file = new ifstream(argv[1]);
-
- int nb_edges, nb_vertices;
- int source, sink;
-
- if(file->good()) {
-
- (*file) >> nb_vertices >> nb_edges;
- (*file) >> source >> sink;
-
- cout << "INPUT nb_edges " << nb_edges << endl;
- cout << "INPUT nb_vertices " << nb_vertices << endl;
- cout << "INPUT source " << source << endl;
- cout << "INPUT sink " << sink << endl;
-
- scalar_t *el = new scalar_t[nb_edges];
- int *ea = new int[nb_edges];
- int *eb = new int[nb_edges];
- int *edge_occupation = new int[nb_edges];
-
- for(int e = 0; e < nb_edges; e++) {
- (*file) >> ea[e] >> eb[e] >> el[e];
- cout << "INPUT_EDGE " << ea[e] << " " << eb[e] << " " << el[e] << endl;
- }
-
- find_best_paths(nb_vertices, nb_edges, el, ea, eb, source, sink,
- edge_occupation);
-
-#ifdef VERBOSE
- // Sanity check on the overall resulting score (the edge lengths
- // have been changed, hence should be the opposite of the sum of
- // the path lengths)
- scalar_t s = 0;
- for(int e = 0; e < nb_edges; e++) {
- if(edge_occupation[e]) s += el[e];
- }
- cout << "RESULT_SANITY_CHECK_SCORE " << s << endl;
-#endif
-
- for(int e = 0; e < nb_edges; e++) {
- if(edge_occupation[e]) {
- cout << "RESULT_OCCUPIED_EDGE " << ea[e] << " " << eb[e] << endl;
- }
- }
-
- delete[] edge_occupation;
- delete[] el;
- delete[] ea;
- delete[] eb;
-
- } else {
-
- cerr << "Can not open " << argv[1] << endl;
-
- delete file;
- exit(EXIT_FAILURE);
-
- }
-
- delete file;
- exit(EXIT_SUCCESS);
-}
class Edge {
public:
- int occupied;
+ int id, occupied;
scalar_t length, work_length;
Vertex *terminal_vertex;
Edge *next, *pred;
public:
int id;
- Edge *first_edge;
+ Edge *root_edge;
scalar_t distance_from_source;
Vertex *pred_vertex;
Edge *pred_edge;
- Vertex() { first_edge = 0; }
+ Vertex() { root_edge = 0; }
inline void add_edge(Edge *e) {
- e->next = first_edge;
+ e->next = root_edge;
e->pred = 0;
- if(first_edge) { first_edge->pred = e; }
- first_edge = e;
+ if(root_edge) { root_edge->pred = e; }
+ root_edge = e;
}
inline void del_edge(Edge *e) {
- if(e == first_edge) { first_edge = e->next; }
+ if(e == root_edge) { root_edge = e->next; }
if(e->pred) { e->pred->next = e->next; }
if(e->next) { e->next->pred = e->pred; }
}
~Graph();
- void find_best_paths();
+ void find_best_paths(int *result_edge_occupation);
void print();
- void print_occupied_edges();
- void dot_print();
};
void Graph::print() {
for(int n = 0; n < nb_vertices; n++) {
- for(Edge *e = vertices[n].first_edge; e; e = e->next) {
- cout << n << " -> " << e->terminal_vertex->id << " " << e->length << endl;
- }
- }
-}
-
-void Graph::print_occupied_edges() {
- for(int n = 0; n < nb_vertices; n++) {
- for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+ cout << n << " -> " << e->terminal_vertex->id << " " << e->length;
if(e->occupied) {
- int a = n, b = e->terminal_vertex->id;
- if(a > b) { int c = a; a = b; b = c; }
- cout << a << " " << b << endl;
+ cout << " *";
}
+ cout << endl;
}
}
}
-void Graph::dot_print() {
- cout << "digraph {" << endl;
- cout << " node[shape=circle];" << endl;
- for(int n = 0; n < nb_vertices; n++) {
- for(Edge *e = vertices[n].first_edge; e; e = e->next) {
- int a = n, b = e->terminal_vertex->id;
- if(e->occupied) {
- int c = a; a = b; b = c;
- cout << " " << a << " -> " << b << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
- } else {
- cout << " " << a << " -> " << b << " [color=gray,label=\"" << e->length << "\"];" << endl;
- }
- }
- }
- cout << "}" << endl;
-}
-
Graph::Graph(int nb_vrt, int nb_edges,
int *from, int *to, scalar_t *lengths,
int src, int snk) {
for(int e = 0; e < nb_edges; e++) {
vertices[from[e]].add_edge(&edge_heap[e]);
edge_heap[e].occupied = 0;
+ edge_heap[e].id = e;
edge_heap[e].length = lengths[e];
edge_heap[e].terminal_vertex = &vertices[to[e]];
}
void Graph::initialize_work_lengths() {
scalar_t length_min = 0;
for(int n = 0; n < nb_vertices; n++) {
- for(Edge *e = vertices[n].first_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].first_edge; e; e = e->next) {
+ for(Edge *e = vertices[n].root_edge; e; e = e->next) {
e->work_length = e->length - length_min;
}
}
void Graph::update_work_length() {
for(int n = 0; n < nb_vertices; n++) {
scalar_t d = vertices[n].distance_from_source;
- for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ for(Edge *e = vertices[n].root_edge; e; e = e->next) {
e->work_length += d - e->terminal_vertex->distance_from_source;
}
}
#ifdef DEBUG
for(int n = 0; n < nb_vertices; n++) {
- for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ for(Edge *e = vertices[n].root_edge; e; e = e->next) {
if(e->work_length < 0) {
cerr << "DEBUG error in find_shortest_path: Edge fixed lengths have to be positive."
<< endl;
new_front_size = 0;
for(int f = 0; f < front_size; f++) {
v = front[f];
- for(Edge *e = v->first_edge; e; e = e->next) {
+ for(Edge *e = v->root_edge; e; e = e->next) {
d = v->distance_from_source + e->work_length;
tv = e->terminal_vertex;
if(d < tv->distance_from_source) {
} while(front_size > 0);
}
-void Graph::find_best_paths() {
+void Graph::find_best_paths(int *result_edge_occupation) {
Vertex **front = new Vertex *[nb_vertices];
Vertex **new_front = new Vertex *[nb_vertices];
}
} while(total_length < 0.0);
- // // We put all occupied edges back to their original orientations
- // for(int n = 0; n < nb_vertices; n++) {
- // Vertex *v = &vertices[n];
- // for(Edge *e = v->first_edge; e; e = e->next) {
- // if(e->occupied) {
- // e->terminal_vertex = v->pred_vertex;
- // e->length = - e->length;
- // e->work_length = 0;
- // v->pred_vertex->del_edge(e);
- // v->add_edge(e);
- // }
- // }
- // }
-
-
delete[] front;
delete[] new_front;
+
+ 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 find_best_paths(int nb_vertices,
+ int nb_edges, int *ea, int *eb, scalar_t *el,
+ int source, int sink,
+ int *result_edge_occupation) {
+ Graph graph(nb_vertices, nb_edges, ea, eb, el, source, sink);
+ graph.find_best_paths(result_edge_occupation);
+}
+
+void dot_print(int nb_vertices,
+ int nb_edges, int *ea, int *eb, scalar_t *el,
+ int source, int sink,
+ int *edge_occupation) {
+ cout << "digraph {" << endl;
+ cout << " node[shape=circle];" << endl;
+ for(int e = 0; e < nb_edges; e++) {
+ if(edge_occupation[e]) {
+ cout << " " << ea[e] << " -> " << eb[e] << " [style=bold,color=black,label=\"" << el[e] << "\"];" << endl;
+ } else {
+ cout << " " << ea[e] << " -> " << eb[e] << " [color=gray,label=\"" << el[e] << "\"];" << endl;
+ }
+ }
+ cout << "}" << endl;
}
//////////////////////////////////////////////////////////////////////
(*file) >> nb_vertices >> nb_edges;
(*file) >> source >> sink;
- // cout << "INPUT nb_edges " << nb_edges << endl;
- // cout << "INPUT nb_vertices " << nb_vertices << endl;
- // cout << "INPUT source " << source << endl;
- // cout << "INPUT sink " << sink << endl;
-
- scalar_t *el = new scalar_t[nb_edges];
- int *ea = new int[nb_edges];
- int *eb = new int[nb_edges];
+ scalar_t *edge_lengths = new scalar_t[nb_edges];
+ int *vertex_from = new int[nb_edges];
+ int *vertex_to = new int[nb_edges];
+ int *result_edge_occupation = new int[nb_edges];
for(int e = 0; e < nb_edges; e++) {
- (*file) >> ea[e] >> eb[e] >> el[e];
+ (*file) >> vertex_from[e] >> vertex_to[e] >> edge_lengths[e];
}
- // for(int e = 0; e < nb_edges; e++) {
- // cout << "INPUT_EDGE " << ea[e] << " " << eb[e] << " " << el[e] << endl;
- // }
-
- Graph graph(nb_vertices, nb_edges, ea, eb, el, source, sink);
+ find_best_paths(nb_vertices, nb_edges,
+ vertex_from, vertex_to, edge_lengths,
+ source, sink,
+ result_edge_occupation);
- graph.find_best_paths();
- // graph.print_occupied_edges();
- graph.dot_print();
+ dot_print(nb_vertices, nb_edges,
+ vertex_from, vertex_to, edge_lengths,
+ source, sink,
+ result_edge_occupation);
- delete[] el;
- delete[] ea;
- delete[] eb;
+ delete[] result_edge_occupation;
+ delete[] edge_lengths;
+ delete[] vertex_from;
+ delete[] vertex_to;
} else {
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