yarrg/rssearch.c

   1 /**/
   2
   3 #include "rscommon.h"
   4
   5 DEBUG_DEFINE_DEBUGF(search);
   6
   7 typedef struct Neighbour {
   8   struct Neighbour *next;
   9   int islandid;
  10   int dist;
  11 } Neighbour;
  12
  13 static Neighbour **neighbours; /* neighbours[islandid]->islandid etc. */
  14 static sqlite3_stmt *ss_neigh;
  15
  16 static int ports[MAX_ROUTELEN];
  17
  18 static Neighbour *get_neighbours(int isle) {
  19   Neighbour **np= &neighbours[isle];
  20   Neighbour *head= *np;
  21   if (head) return head;
  22
  23   SQL_BIND(ss_neigh, 1, isle);
  24   while (SQL_STEP(ss_neigh)) {
  25     Neighbour *add= mmalloc(sizeof(*add));
  26     add->islandid= sqlite3_column_int(ss_neigh, 0);
  27     add->dist= sqlite3_column_int(ss_neigh, 1);
  28     add->next= head;
  29     head= add;
  30   }
  31   SQL_MUST( sqlite3_reset(ss_neigh) );
  32
  33   *np= head;
  34   return head;
  35 }
  36
  37 static double best_absolute, best_perleague;
  38
  39 static double process_route(int nports, int totaldist,
  40                             double overestimate_excepting_tail) {
  41   int i;
  42   int leagues_divisor= totaldist + nports;
  43
  44   ctr_routes_considered++;
  45
  46   debugf("========== ROUTE");
  47   for (i=0; i<nports; i++)
  48     debugf(" %d",ports[i]);
  49   debugf("\n");
  50
  51   if (nports>=2) {
  52     int pair[2], i;
  53     pair[1]= ports[nports-1];
  54     double guess_absolute= overestimate_excepting_tail;
  55
  56     for (i=0; i<nports; i++) {
  57       pair[0]= ports[i];
  58       IslandPair *ip= ipair_get_maybe(pair[0], pair[1]);
  59       if (!ip) continue;
  60       if (ip->route_tail_value < 0) {
  61         ctr_subroute_tails_valued++;
  62         ip->route_tail_value= value_route(2, pair, pair[0]!=pair[1]);
  63       }
  64       guess_absolute += ip->route_tail_value;
  65     }
  66     double guess_perleague= guess_absolute / leagues_divisor;
  67
  68     if (guess_absolute <= best_absolute && guess_perleague <= best_perleague) {
  69       ctr_routes_eliminated++;
  70       debugf(" ELIM %f %f\n", guess_absolute, guess_perleague);
  71       return guess_absolute;
  72     }
  73     debugf(" COMPUTE %f %f\n", guess_absolute, guess_perleague);
  74   }
  75
  76   ctr_routes_valued++;
  77
  78   double absolute= value_route(nports, ports, 0);
  79   double perleague= absolute / leagues_divisor;
  80
  81   if (absolute <= best_absolute && perleague <= best_perleague)
  82     return absolute;
  83
  84   debugf(" SOMEHOW BEST\n");
  85
  86 #define CHK(absperl)                                    \
  87   fprintf(stderr,#absperl " %15f", absperl);            \
  88   if (absperl < best_##absperl) fputs("   ",stderr);    \
  89   else { best_##absperl= absperl; fputs("** ",stderr); }
  90
  91   CHK(absolute)
  92   CHK(perleague)
  93
  94   fputs(" route",stderr);
  95
  96   for (i=0; i<nports; i++)
  97     fprintf(stderr," %d",ports[i]);
  98   putc('\n',stderr);
  99
 100   return absolute;
 101 }
 102
 103 static void recurse(int last_isle,
 104                     int nports, /* excluding last_isle */
 105                     int totaldist /* including last_isle */,
 106                     double last_estimate) {
 107   ports[nports++]= last_isle;
 108   double estimate= process_route(nports, totaldist, last_estimate);
 109   if (nports >= MAX_ROUTELEN) return;
 110
 111   Neighbour *add;
 112   for (add= get_neighbours(last_isle); add; add=add->next) {
 113     int newdist= totaldist + add->dist;
 114     if (newdist > max_dist) continue;
 115
 116     recurse(add->islandid, nports, newdist, estimate);
 117   }
 118 }
 119
 120 void search(int start_isle) {
 121   recurse(start_isle,0,0,1e6);
 122 }
 123
 124 void setup_search(void) {
 125   neighbours= mcalloc(sizeof(*neighbours) * islandtablesz);
 126
 127   SQL_PREPARE(ss_neigh,
 128               "SELECT biid, dist FROM routes WHERE aiid=?");
 129 }