X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=7cd7e52b0248ad960dba87aeef6e0dc10b825ba8;hb=4370046158668af82bad9e18802b184cb00467b5;hp=dc383210e450711218fc69232d112320d61acc28;hpb=740285a747ef0eaf4eefc26935932e1679ab1964;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index dc38321..7cd7e52 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -159,10 +159,10 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
   _sink = &_vertices[sink];
 
   for(int e = 0; e < nb_edges; e++) {
-    _vertices[vertex_from[e]].add_leaving_edge(_edges + e);
+    _vertices[vertex_from[e]].add_leaving_edge(&_edges[e]);
     _edges[e].occupied = 0;
-    _edges[e].origin_vertex = _vertices + vertex_from[e];
-    _edges[e].terminal_vertex = _vertices + vertex_to[e];
+    _edges[e].origin_vertex = &_vertices[vertex_from[e]];
+    _edges[e].terminal_vertex = &_vertices[vertex_to[e]];
   }
 
   for(int v = 0; v < _nb_vertices; v++) {
@@ -192,6 +192,7 @@ MTPGraph::~MTPGraph() {
 void MTPGraph::compute_dp_ranks() {
   Vertex *v;
   Edge *e;
+  int tv;
 
   // This procedure computes for each node the longest link from the
   // source and abort if the graph is not a DAG. It works by removing
@@ -203,54 +204,68 @@ void MTPGraph::compute_dp_ranks() {
   // rank of a node is the iteration at which is it removed, and we
   // set the distance_from_source fields to this value.
 
-  Vertex **with_predecessor = new Vertex *[_nb_vertices];
+  int *nb_predecessors = new int[_nb_vertices];
+  int *without_predecessor = new int[_nb_vertices];
+  int *new_without_predecessor = new int[_nb_vertices];
+  int nb_without_predecessor, new_nb_without_predecessor;
 
-  // All the nodes are with_predecessor at first
   for(int k = 0; k < _nb_vertices; k++) {
-    _vertices[k].distance_from_source = 0;
-    with_predecessor[k] = &_vertices[k];
+    nb_predecessors[k] = 0;
   }
 
-  scalar_t rank = 1;
-  int nb_with_predecessor = _nb_vertices, pred_nb_with_predecessor;
-
-  do {
-    // We set the distance_from_source field of all the vertices with incoming
-    // edges to the current rank value
-    for(int f = 0; f < nb_with_predecessor; f++) {
-      v = with_predecessor[f];
-      for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
-        e->terminal_vertex->distance_from_source = rank;
-      }
+  for(int k = 0; k < _nb_vertices; k++) {
+    v = &_vertices[k];
+    for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
+      tv = int(e->terminal_vertex - _vertices);
+      nb_predecessors[tv]++;
     }
+  }
 
-    pred_nb_with_predecessor = nb_with_predecessor;
-    nb_with_predecessor = 0;
+  nb_without_predecessor = 0;
+  for(int k = 0; k < _nb_vertices; k++) {
+    if(nb_predecessors[k] == 0) {
+      without_predecessor[nb_without_predecessor++] = k;
+    }
+  }
 
-    // We keep all the vertices with incoming nodes
-    for(int f = 0; f < pred_nb_with_predecessor; f++) {
-      v = with_predecessor[f];
-      if(v->distance_from_source == rank) {
-        with_predecessor[nb_with_predecessor++] = v;
+  scalar_t rank = 1;
+  while(nb_without_predecessor > 0) {
+    new_nb_without_predecessor = 0;
+    for(int l = 0; l < nb_without_predecessor; l++) {
+      v = &_vertices[without_predecessor[l]];
+      v->distance_from_source = rank;
+      for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
+        tv = int(e->terminal_vertex - _vertices);
+        nb_predecessors[tv]--;
+        ASSERT(nb_predecessors[tv] >= 0);
+        if(nb_predecessors[tv] == 0) {
+          new_without_predecessor[new_nb_without_predecessor++] = tv;
+        }
       }
     }
 
+    swap(without_predecessor, new_without_predecessor);
+    nb_without_predecessor = new_nb_without_predecessor;
     rank++;
-  } while(nb_with_predecessor < pred_nb_with_predecessor);
-
-  delete[] with_predecessor;
+  }
 
-  if(nb_with_predecessor > 0) {
-    cerr << __FILE__ << ": The graph is not a DAG." << endl;
-    abort();
+  for(int k = 0; k < _nb_vertices; k++) {
+    if(nb_predecessors[k] > 0) {
+      cerr << __FILE__ << ": The graph is not a DAG." << endl;
+      abort();
+    }
   }
+
+  delete[] nb_predecessors;
+  delete[] without_predecessor;
+  delete[] new_without_predecessor;
 }
 
 //////////////////////////////////////////////////////////////////////
 
 void MTPGraph::print(ostream *os) {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     (*os) << e->origin_vertex - _vertices
           << " -> "
           << e->terminal_vertex - _vertices
@@ -268,7 +283,7 @@ void MTPGraph::print_dot(ostream *os) {
   (*os) << "        " << _source - _vertices << " [peripheries=2];" << endl;
   (*os) << "        " << _sink - _vertices << " [peripheries=2];" << endl;
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     (*os) << "        "
           << e->origin_vertex - _vertices
           << " -> "
@@ -286,7 +301,7 @@ void MTPGraph::print_dot(ostream *os) {
 
 void MTPGraph::update_positivized_lengths() {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     e->positivized_length +=
       e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
   }
@@ -298,7 +313,7 @@ void MTPGraph::force_positivized_lengths() {
   scalar_t max_error = 0.0;
 #endif
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
 
     if(e->positivized_length < 0) {
 #ifdef VERBOSE
@@ -441,7 +456,7 @@ void MTPGraph::find_best_paths(scalar_t *lengths) {
   // Put back the graph in its original state (i.e. invert edges which
   // have been inverted in the process)
   for(int k = 0; k < _nb_edges; k++) {
-    e = _edges + k;
+    e = &_edges[k];
     if(e->occupied) { e->invert(); }
   }
 }
@@ -451,13 +466,13 @@ int MTPGraph::retrieve_one_path(Edge *e, Path *path) {
   int l = 0, nb_occupied_next;
 
   if(path) {
-    path->nodes[l++] = e->origin_vertex - _vertices;
+    path->nodes[l++] = int(e->origin_vertex - _vertices);
     path->length = e->length;
   } else l++;
 
   while(e->terminal_vertex != _sink) {
     if(path) {
-      path->nodes[l++] = e->terminal_vertex - _vertices;
+      path->nodes[l++] = int(e->terminal_vertex - _vertices);
       path->length += e->length;
     } else l++;
 
@@ -482,7 +497,7 @@ int MTPGraph::retrieve_one_path(Edge *e, Path *path) {
   }
 
   if(path) {
-    path->nodes[l++] = e->terminal_vertex - _vertices;
+    path->nodes[l++] = int(e->terminal_vertex - _vertices);
     path->length += e->length;
   } else l++;