tactics/ladder.h

   1 #ifndef ZZGO_TACTICS_LADDER_H
   2 #define ZZGO_TACTICS_LADDER_H
   3
   4 /* Reading ladders. */
   5
   6 #include "board.h"
   7 #include "debug.h"
   8
   9 /* Check if escaping on this liberty by given group in atari would play out
  10  * a simple ladder. */
  11 /* Two ways of ladder reading can be enabled separately; simple first-line
  12  * ladders and trivial middle-board ladders. */
  13 static bool is_ladder(struct board *b, coord_t coord, group_t laddered);
  14
  15
  16 bool is_border_ladder(struct board *b, coord_t coord, enum stone lcolor);
  17 bool is_middle_ladder(struct board *b, coord_t coord, enum stone lcolor);
  18 static inline bool
  19 is_ladder(struct board *b, coord_t coord, group_t laddered)
  20 {
  21         enum stone lcolor = board_at(b, group_base(laddered));
  22
  23         if (DEBUGL(6))
  24                 fprintf(stderr, "ladder check - does %s play out %s's laddered group %s?\n",
  25                         coord2sstr(coord, b), stone2str(lcolor), coord2sstr(laddered, b));
  26
  27         /* First, special-case first-line "ladders". This is a huge chunk
  28          * of ladders we actually meet and want to play. */
  29         if (neighbor_count_at(b, coord, S_OFFBOARD) == 1
  30             && neighbor_count_at(b, coord, lcolor) == 1) {
  31                 bool l = is_border_ladder(b, coord, lcolor);
  32                 if (DEBUGL(6)) fprintf(stderr, "border ladder solution: %d\n", l);
  33                 return l;
  34         }
  35
  36         bool l = is_middle_ladder(b, coord, lcolor);
  37         if (DEBUGL(6)) fprintf(stderr, "middle ladder solution: %d\n", l);
  38         return l;
  39 }
  40
  41 #endif