X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=7167cf6c7c3179d97eb1a2b378cd7bba2bc20dcc;hb=14eafbcbbc5cb10464f39596b34eebce0a6922ed;hp=ee6da31de61df9abe9705b41a895763b612ccd00;hpb=8df7c7e77366cb95e9e8e963af9319d9cbac1934;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index ee6da31..7167cf6 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -20,28 +20,31 @@
 
 #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;
 
   // These are the links in the origin_vertex leaving edge list
-  Edge *next, *pred;
+  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;
   Edge *best_pred_edge_to_source;
 
+  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);
@@ -51,7 +54,7 @@ public:
 
 void Edge::revert() {
   length = - length;
-  work_length = 0;
+  positivized_length = 0;
   origin_vertex->del_edge(this);
   terminal_vertex->add_edge(this);
   Vertex *t = terminal_vertex;
@@ -62,55 +65,35 @@ void Edge::revert() {
 //////////////////////////////////////////////////////////////////////
 
 Vertex::Vertex() {
-  root_edge = 0;
+  leaving_edges = 0;
 }
 
 void Vertex::add_edge(Edge *e) {
-  e->next = root_edge;
-  e->pred = 0;
-  if(root_edge) { root_edge->pred = e; }
-  root_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 == root_edge) { root_edge = e->next; }
-  if(e->pred) { e->pred->next = e->next; }
-  if(e->next) { e->next->pred = e->pred; }
+  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; }
 }
 
 //////////////////////////////////////////////////////////////////////
 
-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;
-  }
+Path::Path(int l) {
+  length = l;
+  nodes = new int[length];
 }
 
-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;
+Path::~Path() {
+  delete[] nodes;
 }
 
+//////////////////////////////////////////////////////////////////////
+
 MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
                    int *from, int *to,
                    int source, int sink) {
@@ -137,6 +120,8 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
     _edges[e].terminal_vertex = _vertices + to[e];
   }
 
+  paths = 0;
+  nb_paths = 0;
 }
 
 MTPGraph::~MTPGraph() {
@@ -144,45 +129,88 @@ MTPGraph::~MTPGraph() {
   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_with_min() {
+//////////////////////////////////////////////////////////////////////
+
+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;
+    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
 }
 
@@ -192,6 +220,7 @@ 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++) {
@@ -209,10 +238,11 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   do {
     _new_front_size = 0;
     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;
@@ -235,28 +265,29 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   } while(_front_size > 0);
 }
 
-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].occupied = 0;
+    _edges[e].positivized_length = _edges[e].length;
   }
 
   // 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_work_lengths();
+  update_positivized_lengths();
 
   // #warning
-  // initialize_work_lengths_with_min();
+  // 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;
 
@@ -271,7 +302,7 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
       // 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
         v = _sink;
@@ -279,6 +310,8 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
           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;
         }
       }
@@ -289,6 +322,60 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
   for(int k = 0; k < _nb_edges; k++) {
     Edge *e = _edges + k;
     if(e->occupied) { e->revert(); }
-    result_edge_occupation[k] = e->occupied;
+  }
+}
+
+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;
+  }
+
+  if(nodes) { nodes[l++] = e->terminal_vertex->id; }
+  else l++;
+
+  return l;
+}
+
+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++;
+    }
   }
 }