X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.h;h=c9105203405e26a5bff5c239fea9b34fcd46ca48;hb=14e3b33cbe1e0d7deb0b4aa697f6c8b5d43e2963;hp=9b342486b18735503697dae564b30d7a1425d9be;hpb=43c776de4f51009b32b5580347aa6c18cfefa929;p=mtp.git

diff --git a/mtp_graph.h b/mtp_graph.h
index 9b34248..c910520 100644
--- a/mtp_graph.h
+++ b/mtp_graph.h
@@ -39,8 +39,8 @@ class Edge;
 class MTPGraph {
   // Uses the estimated vertex distances to the source to make all the
   // edge lengths positive, resulting in an identical added value to
-  // the total length of any path from source to a certain node (in
-  // particular the sink)
+  // all the paths from the same initial node to the same final node
+  // (in particular from source to sink)
   void update_positivized_lengths();
 
   // It may happen that numerical errors in update_positivized_lengths
@@ -49,18 +49,26 @@ class MTPGraph {
   // the total correction when compiled in VERBOSE mode.
   void force_positivized_lengths();
 
-  // Set the edge pred_edge_toward_source correspondingly to the path
-  // of shortest length. The current implementation is not Dijkstra's!
+  void decrease_distance_in_heap(Vertex *v);
+  void increase_distance_in_heap(Vertex *v);
+
+  // Visit the vertices according to _dp_order and simply update their
+  // distance to the source
+  void dp_distance_propagation();
+
+  // Set in every vertex pred_edge_toward_source correspondingly to
+  // the path of shortest length. The current implementation is
+  // Dijkstra with a Binary Heap (and not with Fibonnaci heap (yet))
   void find_shortest_path();
 
-  // Follows the path starting on edge e and returns its length. If
-  // nodes is non-null, stores in it the nodes met along the path.
+  // Follows the path starting on edge e and returns the number of
+  // nodes to reach the sink. If path is non-null, stores in it the
+  // nodes met along the path, and computes path->length properly.
   int retrieve_one_path(Edge *e, Path *path);
 
-  // Returns if the graph is a DAG
-  int is_dag();
-
-  Vertex **_front, **_new_front;
+  // Set the distance_from_source fields to the number of DP
+  // iterations needed to update it. Abort if the graph is not a DAG.
+  int compute_dp_distances();
 
   int _nb_vertices, _nb_edges;
   Vertex *_source, *_sink;
@@ -68,6 +76,14 @@ class MTPGraph {
   Edge *_edges;
   Vertex *_vertices;
 
+  // For Dijkstra
+  Vertex **_heap;
+  int _heap_size;
+
+  // Updating the distances from the source in that order will work in
+  // the original graph (which has to be a DAG)
+  Vertex **_dp_order;
+
 public:
 
   // These variables are filled when retrieve_disjoint_paths is called
@@ -79,7 +95,12 @@ public:
 
   ~MTPGraph();
 
+  // Compute the family of paths with minimum total length, set the
+  // edge occupied fields accordingly.
   void find_best_paths(scalar_t *lengths);
+
+  // Retrieve the paths corresponding to the occupied edges, and save
+  // the result in the nb_paths and paths fields.
   void retrieve_disjoint_paths();
 
   void print(ostream *os);