chiark / gitweb /
WIP routesearch; route tail guesswork pruning optimisation
[ypp-sc-tools.db-live.git] / yarrg / rssearch.c
index f14b0cd..eb40a47 100644 (file)
@@ -36,18 +36,44 @@ static Neighbour *get_neighbours(int isle) {
 
 static double best_absolute, best_perleague;
 
-static void process_route(int nports, int totaldist) {
+static double process_route(int nports, int totaldist,
+                           double overestimate_excepting_tail) {
   int i;
+  int leagues_divisor= totaldist + nports;
 
   debugf("========== ROUTE");
   for (i=0; i<nports; i++)
     debugf(" %d",ports[i]);
   debugf("\n");
 
-  double absolute= value_route(nports, ports);
-  double perleague= absolute / (totaldist + nports);
+  if (nports>=2) {
+    int pair[2], i;
+    pair[1]= ports[nports-1];
+    double guess_absolute= overestimate_excepting_tail;
+    
+    for (i=0; i<nports; i++) {
+      pair[0]= ports[i];
+      IslandPair *ip= ipair_get(ports[nports-2], ports[nports-1]);
+      if (ip->route_tail_value < 0)
+       ip->route_tail_value= value_route(2, pair, pair[0]!=pair[1]);
+      guess_absolute += ip->route_tail_value;
+    }
+    double guess_perleague= guess_absolute / leagues_divisor;
+
+    if (guess_absolute <= best_absolute && guess_perleague <= best_perleague) {
+      debugf(" ELIM %f %f\n", guess_absolute, guess_perleague);
+      return guess_absolute;
+    }
+    debugf(" COMPUTE %f %f\n", guess_absolute, guess_perleague);
+  }
+
+  double absolute= value_route(nports, ports, 0);
+  double perleague= absolute / leagues_divisor;
 
-  if (absolute < best_absolute && perleague < best_perleague) return;
+  if (absolute <= best_absolute && perleague <= best_perleague)
+    return absolute;
+
+  debugf(" SOMEHOW BEST\n");
 
 #define CHK(absperl)                                   \
   fprintf(stderr,#absperl " %15f", absperl);           \
@@ -62,13 +88,16 @@ static void process_route(int nports, int totaldist) {
   for (i=0; i<nports; i++)
     fprintf(stderr," %d",ports[i]);
   putc('\n',stderr);
+
+  return absolute;
 }
 
 static void recurse(int last_isle,
                    int nports, /* excluding last_isle */
-                   int totaldist /* including last_isle */) {
+                   int totaldist /* including last_isle */,
+                   double last_estimate) {
   ports[nports++]= last_isle;
-  process_route(nports, totaldist);
+  double estimate= process_route(nports, totaldist, last_estimate);
   if (nports >= MAX_ROUTELEN) return;
 
   Neighbour *add;
@@ -76,12 +105,12 @@ static void recurse(int last_isle,
     int newdist= totaldist + add->dist;
     if (newdist > max_dist) continue;
 
-    recurse(add->islandid, nports, newdist);
+    recurse(add->islandid, nports, newdist, estimate);
   }
 }
 
 void search(int start_isle) {
-  recurse(start_isle,0,0);
+  recurse(start_isle,0,0,1e6);
 }
 
 void setup_search(void) {