X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp.cc;h=b4006503dac3e37d760666a03c15ab0bc9cdd749;hb=3fe1f714514a55322e22717eeddf76f9f019c658;hp=529ba80f2d45c1ff48fa548835b525b7429d82a6;hpb=425acf9068dac38bccb97b12f1b423db5787e294;p=mtp.git

diff --git a/mtp.cc b/mtp.cc
index 529ba80..b400650 100644
--- a/mtp.cc
+++ b/mtp.cc
@@ -18,6 +18,10 @@
 
 // Multi-Tracked Path
 
+// Takes the graph description file as input and produces a dot file.
+
+// EXAMPLE: ./mtp ./graph2.txt  | dot -T pdf -o- | xpdf -
+
 // #define VERBOSE
 
 #include <iostream>
@@ -44,7 +48,7 @@ class Vertex;
 
 class Edge {
 public:
-  int occupied;
+  int id, occupied;
   scalar_t length, work_length;
   Vertex *terminal_vertex;
   Edge *next, *pred;
@@ -52,65 +56,55 @@ public:
 
 class Vertex {
 public:
-  int id;
-  // These are the leaving edges
-  Edge *first_edge;
-  scalar_t distance;
-
+  int id, iteration;
+  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) {
-    if(first_edge) { first_edge->pred = e; }
-    e->next = first_edge;
+    e->next = root_edge;
     e->pred = 0;
-    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; }
   }
 };
 
 class Graph {
-public:
+  void initialize_work_lengths();
+  void update_work_length();
+  void find_shortest_path(Vertex **front, Vertex **new_front);
+
   int nb_vertices;
   Edge *edge_heap;
   Vertex *vertices;
   Vertex *source, *sink;
-
+public:
   Graph(int nb_vertices, int nb_edges, int *from, int *to, scalar_t *lengths,
         int source, int sink);
+
   ~Graph();
 
-  void initialize_work_lengths();
-  void update_work_length();
-  void find_shortest_path();
-  void find_best_paths();
+  void find_best_paths(int *result_edge_occupation);
   void print();
-  void print_occupied_edges();
 };
 
 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;
     }
   }
 }
@@ -133,6 +127,7 @@ Graph::Graph(int nb_vrt, int nb_edges,
   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]];
   }
@@ -146,12 +141,12 @@ Graph::~Graph() {
 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;
     }
   }
@@ -159,16 +154,14 @@ void Graph::initialize_work_lengths() {
 
 void Graph::update_work_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->work_length += d - e->terminal_vertex->distance;
+    scalar_t d = vertices[n].distance_from_source;
+    for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+      e->work_length += d - e->terminal_vertex->distance_from_source;
     }
   }
 }
 
-void Graph::find_shortest_path() {
-  Vertex **front = new Vertex *[nb_vertices];
-  Vertex **new_front = new Vertex *[nb_vertices];
+void Graph::find_shortest_path(Vertex **front, Vertex **new_front) {
   Vertex **tmp_front;
   int tmp_front_size;
   Vertex *v, *tv;
@@ -176,9 +169,9 @@ void Graph::find_shortest_path() {
 
 #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."
+        cerr << "DEBUG error in find_shortest_path: Edge work lengths have to be positive."
              << endl;
         abort();
       }
@@ -187,27 +180,34 @@ void Graph::find_shortest_path() {
 #endif
 
   for(int v = 0; v < nb_vertices; v++) {
-    vertices[v].distance = FLT_MAX;
+    vertices[v].distance_from_source = FLT_MAX;
     vertices[v].pred_vertex = 0;
     vertices[v].pred_edge = 0;
+    vertices[v].iteration = 0;
   }
 
+  int iteration = 0;
+
   int front_size = 0, new_front_size;
   front[front_size++] = source;
-  source->distance = 0;
+  source->distance_from_source = 0;
 
   do {
     new_front_size = 0;
+    iteration++;
     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->work_length;
+      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) {
-          tv->distance = d;
+        if(d < tv->distance_from_source) {
+          tv->distance_from_source = d;
           tv->pred_vertex = v;
           tv->pred_edge = e;
-          new_front[new_front_size++] = tv;
+          if(tv->iteration < iteration) {
+            new_front[new_front_size++] = tv;
+            tv->iteration = iteration;
+          }
         }
       }
     }
@@ -220,41 +220,29 @@ void Graph::find_shortest_path() {
     new_front_size = front_size;
     front_size = tmp_front_size;
   } while(front_size > 0);
-
-  delete[] front;
-  delete[] new_front;
 }
 
-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];
+
   scalar_t total_length;
 
   initialize_work_lengths();
 
   do {
-#ifdef VERBOSE
-    print();
-#endif
-
     total_length = 0.0;
-    find_shortest_path();
+    find_shortest_path(front, new_front);
     update_work_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
@@ -270,6 +258,40 @@ void Graph::find_best_paths() {
       }
     }
   } while(total_length < 0.0);
+
+  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;
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -291,28 +313,29 @@ int main(int argc, char **argv) {
     (*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];
-      cout << "INPUT_EDGE " << ea[e] << " " << eb[e] << " " << el[e] << endl;
+      (*file) >> vertex_from[e] >> vertex_to[e] >> edge_lengths[e];
     }
 
-    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();
+    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 {