X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=cc816c95f899a16220fa09ed0ab3f151578d7329;hb=e9fbecf1c13c63a717c1b359c24287dbce23d4ed;hp=1dd6ff22a59b4c25c4e52650256f52ed82568b17;hpb=f72214033cc9a12fb40470a5122f3c4686cdc2d1;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index 1dd6ff2..cc816c9 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -20,158 +20,213 @@
 
 #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;
@@ -183,15 +238,40 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   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;
@@ -208,53 +288,72 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
     _new_front_size = _front_size;
     _front_size = tmp_front_size;
   } while(_front_size > 0);
+
+#ifdef DEBUG
+  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();
+  cout << "********************************************************" << endl;
+  // print_dot(&cout);
+
+  // 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;
         }
       }
     }
@@ -262,44 +361,62 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
   } 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++;
     }
   }
 }