--- /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
+
+class Vertex;
+
+class Edge {
+public:
+ int occupied;
+ scalar_t length, fixed_length;
+ Vertex *terminal_vertex;
+ Edge *next, *pred;
+};
+
+class Vertex {
+public:
+ // These are the leaving edges
+ Edge *first_edge;
+ scalar_t distance;
+
+ Vertex *pred_vertex;
+ Edge *pred_edge;
+
+ Vertex() { first_edge = 0; }
+
+ inline void add_edge(Edge *e) {
+ if(first_edge) { first_edge->pred = e; }
+ e->next = first_edge;
+ e->pred = 0;
+ first_edge = e;
+ }
+
+ inline void del_edge(Edge *e) {
+ if(e == first_edge) { first_edge = e->next; }
+ if(e->pred) { e->pred->next = e->next; }
+ if(e->next) { e->next->pred = e->pred; }
+ }
+};
+
+class Graph {
+public:
+ int nb_vertices;
+ Edge *edge_heap;
+ Vertex *vertices;
+ Vertex *source, *sink;
+
+ Graph(int nb_vertices, int nb_edges, int *from, int *to, scalar_t *lengths,
+ int source, int sink);
+ ~Graph();
+
+ void initialize_fixed_lengths();
+ void update_fixed_length();
+ void find_shortest_path();
+ void find_best_paths();
+ void print();
+};
+
+void Graph::print() {
+ for(int n = 0; n < nb_vertices; n++) {
+ cout << "VERTEX [" << n << "] ";
+ for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ cout << " " << e->length;
+ }
+ cout << endl;
+ }
+}
+
+Graph::Graph(int nb_vrt, int nb_edges,
+ int *from, int *to, scalar_t *lengths,
+ int src, int snk) {
+ nb_vertices = nb_vrt;
+
+ edge_heap = new Edge[nb_edges];
+ vertices = new Vertex[nb_vertices];
+
+ source = &vertices[src];
+ sink = &vertices[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].length = lengths[e];
+ edge_heap[e].terminal_vertex = &vertices[to[e]];
+ }
+}
+
+Graph::~Graph() {
+ delete[] vertices;
+ delete[] edge_heap;
+}
+
+void Graph::initialize_fixed_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) {
+ 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) {
+ e->fixed_length = e->length - length_min;
+ }
+ }
+}
+
+void Graph::update_fixed_length() {
+ for(int n = 0; n < nb_vertices; n++) {
+ scalar_t d = vertices[n].distance;
+ for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ e->fixed_length += d - e->terminal_vertex->distance;
+ }
+ }
+}
+
+void Graph::find_shortest_path() {
+ Vertex **front = new Vertex *[nb_vertices];
+ Vertex **new_front = new Vertex *[nb_vertices];
+ Vertex **tmp_front;
+ int tmp_front_size;
+ Vertex *v, *tv;
+ scalar_t d;
+
+#ifdef DEBUG
+ for(int n = 0; n < nb_vertices; n++) {
+ for(Edge *e = vertices[n].first_edge; e; e = e->next) {
+ if(e->fixed_length < 0) {
+ cerr << "DEBUG error in find_shortest_path: Edge fixed lengths have to be positive."
+ << endl;
+ abort();
+ }
+ }
+ }
+#endif
+
+ for(int v = 0; v < nb_vertices; v++) {
+ vertices[v].distance = FLT_MAX;
+ vertices[v].pred_vertex = 0;
+ vertices[v].pred_edge = 0;
+ }
+
+ int front_size = 0, new_front_size;
+ front[front_size++] = source;
+ source->distance = 0;
+
+ do {
+ 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) {
+ d = v->distance + e->fixed_length;
+ tv = e->terminal_vertex;
+ if(d < tv->distance) {
+ tv->distance = d;
+ tv->pred_vertex = v;
+ tv->pred_edge = e;
+ new_front[new_front_size++] = tv;
+ }
+ }
+ }
+
+ tmp_front = new_front;
+ new_front = front;
+ front = tmp_front;
+
+ tmp_front_size = new_front_size;
+ new_front_size = front_size;
+ front_size = tmp_front_size;
+ cout << "front_size = " << front_size << endl;
+ } while(front_size > 0);
+
+ delete[] front;
+ delete[] new_front;
+}
+
+void Graph::find_best_paths() {
+ scalar_t total_length;
+
+ initialize_fixed_lengths();
+
+ do {
+ print();
+
+ total_length = 0.0;
+ find_shortest_path();
+ update_fixed_length();
+
+ // Do we reach the sink?
+ if(sink->pred_edge) {
+
+#ifdef VERBOSE
+ cout << "VERBOSE there is a path reaching the sink" << endl;
+#endif
+
+ // 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;
+ }
+
+#ifdef VERBOSE
+ cout << "VERBOSE total_length " << total_length << endl;
+#endif
+
+ // If that length is negative
+ if(total_length < 0.0) {
+ // 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;
+ e->occupied = 1 - e->occupied;
+ e->length = - e->length;
+ e->fixed_length = - e->fixed_length;
+ v->pred_vertex->del_edge(e);
+ v->add_edge(e);
+ cout << "INVERT!" << endl;
+ }
+ }
+ }
+ } while(total_length < 0.0);
+}
+
+//////////////////////////////////////////////////////////////////////
+
+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];
+
+ 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;
+ }
+
+ Graph graph(nb_vertices, nb_edges, ea, eb, el, source, sink);
+
+ graph.find_best_paths();
+
+ delete[] el;
+ delete[] ea;
+ delete[] eb;
+
+ } else {
+
+ cerr << "Can not open " << argv[1] << endl;
+
+ delete file;
+ exit(EXIT_FAILURE);
+
+ }
+
+ delete file;
+ exit(EXIT_SUCCESS);
+}
projects / mtp.git / commitdiff