X-Git-Url: https://www.fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=2832e71f6ca8fcae738357e4c5872d4a39e9f442;hb=276df8ea8b9761cc729048d8e5c42670debc5825;hp=6c97c5d09e207c831416b15880e8a67273946dd6;hpb=ecead8ae3e8f3fdc43f6f8b2d7327e253cdae637;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index 6c97c5d..2832e71 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -63,9 +63,7 @@ void Edge::invert() {
   positivized_length = - positivized_length;
   origin_vertex->del_leaving_edge(this);
   terminal_vertex->add_leaving_edge(this);
-  Vertex *t = terminal_vertex;
-  terminal_vertex = origin_vertex;
-  origin_vertex = t;
+  swap(terminal_vertex, origin_vertex);
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -169,7 +167,7 @@ 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.
@@ -261,7 +259,7 @@ void MTPGraph::force_positivized_lengths() {
 #endif
 }
 
-int MTPGraph::compute_dp_distances() {
+int MTPGraph::compute_dp_ranks() {
   Vertex *v;
   Edge *e;
 
@@ -271,7 +269,9 @@ 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];
 
@@ -281,16 +281,16 @@ 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;
       }
     }
 
@@ -300,12 +300,12 @@ 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;