X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=343ebf79a60a98d145138891d286ec70915280e0;hb=9aa2c8c57bbe0ac533d081fa3917aa037e65c766;hp=33d5a4ff0d8bdd191467b5cdaf8fc607108fb5a3;hpb=86c860c0f43a9130e4121072620961fc892ed83f;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index 33d5a4f..343ebf7 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -110,20 +110,21 @@ void Vertex::increase_distance_in_heap(Vertex **heap, int heap_size) {
   Vertex **c1, **c2, **h;
   // omg, that's beautiful
   h = heap_slot;
-  while(c1 = heap + 2 * (h - heap + 1) - 1, c2 = c1 + 1,
-        (c1 < heap + heap_size && (*c1)->distance_from_source < (*h)->distance_from_source)
-        ||
-        (c2 < heap + heap_size && (*c2)->distance_from_source < (*h)->distance_from_source)
-        ) {
-    if(c1 < heap + heap_size &&
-     !(c2 < heap + heap_size && (*c2)->distance_from_source < (*c1)->distance_from_source)){
-      swap(*c1, *h);
-      swap((*c1)->heap_slot, (*h)->heap_slot);
-      h = c1;
-    } else {
+  while(c1 = heap + 2 * (h - heap) + 1,
+        c1 < heap + heap_size &&
+        (c2 = c1 + 1,
+         (*c1)->distance_from_source < (*h)->distance_from_source
+         ||
+         (c2 < heap + heap_size && (*c2)->distance_from_source < (*h)->distance_from_source)
+         )) {
+    if(c2 < heap + heap_size && (*c2)->distance_from_source <= (*c1)->distance_from_source) {
       swap(*c2, *h);
       swap((*c2)->heap_slot, (*h)->heap_slot);
       h = c2;
+    } else {
+      swap(*c1, *h);
+      swap((*c1)->heap_slot, (*h)->heap_slot);
+      h = c1;
     }
   }
 }
@@ -168,7 +169,7 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
   paths = 0;
   nb_paths = 0;
 
-  if(compute_dp_distances()) {
+  if(compute_dp_ranks()) {
     // Here the distance_from_source field of every vertex is the
     // number of DP iterations needed to update it. Hence we only have
     // to process the vertex in that order.
@@ -260,7 +261,7 @@ void MTPGraph::force_positivized_lengths() {
 #endif
 }
 
-int MTPGraph::compute_dp_distances() {
+int MTPGraph::compute_dp_ranks() {
   Vertex *v;
   Edge *e;
 
@@ -270,7 +271,9 @@ int MTPGraph::compute_dp_distances() {
   // removes the source, then the nodes with incoming edge only from
   // the source, etc. If it can remove all the nodes that way, the
   // graph is a DAG. If at some point it can not remove node anymore
-  // and there are some remaining nodes, the graph is not a DAG.
+  // and there are some remaining nodes, the graph is not a DAG. The
+  // rank of a node is the iteration at which is it removed, and we
+  // set the distance_from_source fields to this value.
 
   Vertex **active = new Vertex *[_nb_vertices];
 
@@ -280,16 +283,16 @@ int MTPGraph::compute_dp_distances() {
     active[k] = &_vertices[k];
   }
 
-  scalar_t nb_iterations = 1;
+  scalar_t rank = 1;
   int nb_active = _nb_vertices, pred_nb_active;
 
   do {
     // We set the distance_from_source field of all the vertices with incoming
-    // edges to the current nb_iterations value
+    // edges to the current rank value
     for(int f = 0; f < nb_active; f++) {
       v = active[f];
       for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
-        e->terminal_vertex->distance_from_source = nb_iterations;
+        e->terminal_vertex->distance_from_source = rank;
       }
     }
 
@@ -299,12 +302,12 @@ int MTPGraph::compute_dp_distances() {
     // We keep all the vertices with incoming nodes
     for(int f = 0; f < pred_nb_active; f++) {
       v = active[f];
-      if(v->distance_from_source == nb_iterations) {
+      if(v->distance_from_source == rank) {
         active[nb_active++] = v;
       }
     }
 
-    nb_iterations++;
+    rank++;
   } while(nb_active < pred_nb_active);
 
   delete[] active;