11 struct selfatari_state
{
13 group_t groupids
[S_MAX
][4];
15 /* This is set if this move puts a group out of _all_
16 * liberties; we need to watch out for snapback then. */
17 bool friend_has_no_libs
;
18 /* We may have one liberty, but be looking for one more.
19 * In that case, @needs_more_lib is id of group
20 * already providing one, don't consider it again. */
21 group_t needs_more_lib
;
22 /* ID of the first liberty, providing it again is not
24 coord_t needs_more_lib_except
;
28 examine_friendly_groups(struct board
*b
, enum stone color
, coord_t to
, struct selfatari_state
*s
)
30 for (int i
= 0; i
< s
->groupcts
[color
]; i
++) {
31 /* We can escape by connecting to this group if it's
33 group_t g
= s
->groupids
[color
][i
];
35 if (board_group_info(b
, g
).libs
== 1) {
36 if (!s
->needs_more_lib
)
37 s
->friend_has_no_libs
= true;
38 // or we already have a friend with 1 lib
42 /* Could we self-atari the group here? */
43 if (board_group_info(b
, g
).libs
> 2)
46 /* We need to have another liberty, and
47 * it must not be the other liberty of
49 int lib2
= board_group_info(b
, g
).lib
[0];
50 if (lib2
== to
) lib2
= board_group_info(b
, g
).lib
[1];
51 /* Maybe we already looked at another
52 * group providing one liberty? */
53 if (s
->needs_more_lib
&& s
->needs_more_lib
!= g
54 && s
->needs_more_lib_except
!= lib2
)
57 /* Can we get the liberty locally? */
58 /* Yes if we are route to more liberties... */
59 if (s
->groupcts
[S_NONE
] > 1)
61 /* ...or one liberty, but not lib2. */
62 if (s
->groupcts
[S_NONE
] > 0
63 && !coord_is_adjecent(lib2
, to
, b
))
66 /* ...ok, then we can still contribute a liberty
67 * later by capturing something. */
68 s
->needs_more_lib
= g
;
69 s
->needs_more_lib_except
= lib2
;
70 s
->friend_has_no_libs
= false;
77 examine_enemy_groups(struct board
*b
, enum stone color
, coord_t to
, struct selfatari_state
*s
)
79 /* We may be able to gain a liberty by capturing this group. */
80 group_t can_capture
= 0;
82 /* Examine enemy groups: */
83 for (int i
= 0; i
< s
->groupcts
[stone_other(color
)]; i
++) {
84 /* We can escape by capturing this group if it's in atari. */
85 group_t g
= s
->groupids
[stone_other(color
)][i
];
86 if (board_group_info(b
, g
).libs
> 1)
89 /* But we need to get to at least two liberties by this;
90 * we already have one outside liberty, or the group is
91 * more than 1 stone (in that case, capturing is always
93 if (s
->groupcts
[S_NONE
] > 0 || !group_is_onestone(b
, g
))
95 /* ...or, it's a ko stone, */
96 if (neighbor_count_at(b
, g
, color
) + neighbor_count_at(b
, g
, S_OFFBOARD
) == 3) {
97 /* and we don't have a group to save: then, just taking
98 * single stone means snapback! */
99 if (!s
->friend_has_no_libs
)
102 /* ...or, we already have one indirect liberty provided
103 * by another group. */
104 if (s
->needs_more_lib
|| (can_capture
&& can_capture
!= g
))
111 fprintf(stderr
, "no cap group\n");
113 if (!s
->needs_more_lib
&& !can_capture
&& !s
->groupcts
[S_NONE
]) {
114 /* We have no hope for more fancy tactics - this move is simply
115 * a suicide, not even a self-atari. */
117 fprintf(stderr
, "suicide\n");
120 /* XXX: I wonder if it makes sense to continue if we actually
121 * just !s->needs_more_lib. */
127 setup_nakade_or_snapback(struct board
*b
, enum stone color
, coord_t to
, struct selfatari_state
*s
)
129 /* There is another possibility - we can self-atari if it is
130 * a nakade: we put an enemy group in atari from the inside. */
131 /* This branch also allows eyes falsification:
132 * O O O . . (This is different from throw-in to false eye
133 * X X O O . checked below in that there is no X stone at the
134 * X . X O . right of the star point in this diagram.)
137 /* TODO: Allow to only nakade if the created shape is dead
138 * (http://senseis.xmp.net/?Nakade). */
140 /* This branch also covers snapback, which is kind of special
141 * nakade case. ;-) */
142 for (int i
= 0; i
< s
->groupcts
[stone_other(color
)]; i
++) {
143 group_t g
= s
->groupids
[stone_other(color
)][i
];
144 if (board_group_info(b
, g
).libs
!= 2)
146 /* Simple check not to re-examine the same group. */
147 if (i
> 0 && s
->groupids
[stone_other(color
)][i
] == s
->groupids
[stone_other(color
)][i
- 1])
150 /* We must make sure the other liberty of that group:
151 * (i) is an internal liberty
152 * (ii) filling it to capture our group will not gain
155 /* Let's look at the other liberty neighbors: */
156 int lib2
= board_group_info(b
, g
).lib
[0];
157 if (lib2
== to
) lib2
= board_group_info(b
, g
).lib
[1];
158 foreach_neighbor(b
, lib2
, {
159 /* This neighbor of course does not contribute
160 * anything to the enemy. */
161 if (board_at(b
, c
) == S_OFFBOARD
)
164 /* If the other liberty has empty neighbor,
165 * it must be the original liberty; otherwise,
166 * since the whole group has only 2 liberties,
167 * the other liberty may not be internal and
168 * we are nakade'ing eyeless group from outside,
169 * which is stupid. */
170 if (board_at(b
, c
) == S_NONE
) {
177 int g2
= group_at(b
, c
);
178 /* If the neighbor is of our color, it must
179 * be our group; if it is a different group,
180 * it must not be in atari. */
181 /* X X X X We will not allow play on 'a',
182 * X X a X because 'b' would capture two
183 * X O b X different groups, forming two
185 if (board_at(b
, c
) == color
) {
186 if (board_group_info(b
, group_at(b
, c
)).libs
> 1)
188 /* Our group == one of the groups
189 * we (@to) are connected to. */
191 for (j
= 0; j
< 4; j
++)
192 if (s
->groupids
[color
][j
] == g2
)
199 /* The neighbor is enemy color. It's ok if
200 * it's still the same group or this is its
202 if (g
== g2
|| board_group_info(b
, g2
).libs
== 1)
204 /* Otherwise, it must have the exact same
205 * liberties as the original enemy group. */
206 if (board_group_info(b
, g2
).libs
== 2
207 && (board_group_info(b
, g2
).lib
[0] == to
208 || board_group_info(b
, g2
).lib
[1] == to
))
214 /* Now, we must distinguish between nakade and eye
215 * falsification; we must not falsify an eye by more
216 * than two stones. */
217 if (s
->groupcts
[color
] < 1 ||
218 (s
->groupcts
[color
] == 1 && group_is_onestone(b
, s
->groupids
[color
][0])))
221 /* We would create more than 2-stone group; in that
222 * case, the liberty of our result must be lib2,
223 * indicating this really is a nakade. */
224 for (int j
= 0; j
< s
->groupcts
[color
]; j
++) {
225 group_t g2
= s
->groupids
[color
][j
];
226 assert(board_group_info(b
, g2
).libs
<= 2);
227 if (board_group_info(b
, g2
).libs
== 2) {
228 if (board_group_info(b
, g2
).lib
[0] != lib2
229 && board_group_info(b
, g2
).lib
[1] != lib2
)
232 assert(board_group_info(b
, g2
).lib
[0] == to
);
238 /* Unless we are dealing with snapback setup, we don't need to look
240 if (s
->groupcts
[color
])
248 check_throwin(struct board
*b
, enum stone color
, coord_t to
, struct selfatari_state
*s
)
250 /* We can be throwing-in to false eye:
251 * X X X O X X X O X X X X X
252 * X . * X * O . X * O O . X
253 * # # # # # # # # # # # # # */
254 /* We cannot sensibly throw-in into a corner. */
255 if (neighbor_count_at(b
, to
, S_OFFBOARD
) < 2
256 && neighbor_count_at(b
, to
, stone_other(color
))
257 + neighbor_count_at(b
, to
, S_OFFBOARD
) == 3
258 && board_is_false_eyelike(b
, to
, stone_other(color
))) {
259 assert(s
->groupcts
[color
] <= 1);
260 /* Single-stone throw-in may be ok... */
261 if (s
->groupcts
[color
] == 0) {
262 /* O X . There is one problem - when it's
263 * . * X actually not a throw-in!
265 foreach_neighbor(b
, to
, {
266 if (board_at(b
, c
) == S_NONE
) {
267 /* Is the empty neighbor an escape path? */
268 /* (Note that one S_NONE neighbor is already @to.) */
269 if (neighbor_count_at(b
, c
, stone_other(color
))
270 + neighbor_count_at(b
, c
, S_OFFBOARD
) < 2)
277 /* Multi-stone throwin...? */
278 assert(s
->groupcts
[color
] == 1);
279 group_t g
= s
->groupids
[color
][0];
281 assert(board_group_info(b
, g
).libs
<= 2);
282 /* Suicide is definitely NOT ok, no matter what else
284 if (board_group_info(b
, g
).libs
== 1)
287 /* In that case, we must be connected to at most one stone,
288 * or throwin will not destroy any eyes. */
289 if (group_is_onestone(b
, g
))
296 is_bad_selfatari_slow(struct board
*b
, enum stone color
, coord_t to
)
299 fprintf(stderr
, "sar check %s %s\n", stone2str(color
), coord2sstr(to
, b
));
300 /* Assess if we actually gain any liberties by this escape route.
301 * Note that this is not 100% as we cannot check whether we are
302 * connecting out or just to ourselves. */
304 struct selfatari_state s
;
305 memset(&s
, 0, sizeof(s
));
308 foreach_neighbor(b
, to
, {
309 enum stone color
= board_at(b
, c
);
310 s
.groupids
[color
][s
.groupcts
[color
]++] = group_at(b
, c
);
313 /* We have shortage of liberties; that's the point. */
314 assert(s
.groupcts
[S_NONE
] <= 1);
316 d
= examine_friendly_groups(b
, color
, to
, &s
);
321 fprintf(stderr
, "no friendly group\n");
323 d
= examine_enemy_groups(b
, color
, to
, &s
);
328 fprintf(stderr
, "no escape\n");
330 d
= setup_nakade_or_snapback(b
, color
, to
, &s
);
335 fprintf(stderr
, "no nakade group\n");
337 d
= check_throwin(b
, color
, to
, &s
);
342 fprintf(stderr
, "no throw-in group\n");
344 /* No way to pull out, no way to connect out. This really
345 * is a bad self-atari! */
350 /* Is this ladder breaker friendly for the one who catches ladder. */
352 ladder_catcher(struct board
*b
, int x
, int y
, enum stone laddered
)
354 enum stone breaker
= board_atxy(b
, x
, y
);
355 return breaker
== stone_other(laddered
) || breaker
== S_OFFBOARD
;
359 is_border_ladder(struct board
*b
, coord_t coord
, enum stone lcolor
)
361 int x
= coord_x(coord
, b
), y
= coord_y(coord
, b
);
364 fprintf(stderr
, "border ladder\n");
365 /* Direction along border; xd is horiz. border, yd vertical. */
367 if (board_atxy(b
, x
+ 1, y
) == S_OFFBOARD
|| board_atxy(b
, x
- 1, y
) == S_OFFBOARD
)
371 /* Direction from the border; -1 is above/left, 1 is below/right. */
372 int dd
= (board_atxy(b
, x
+ yd
, y
+ xd
) == S_OFFBOARD
) ? 1 : -1;
374 fprintf(stderr
, "xd %d yd %d dd %d\n", xd
, yd
, dd
);
380 /* This is normally caught, unless we have friends both above
382 if (board_atxy(b
, x
+ xd
* 2, y
+ yd
* 2) == lcolor
383 && board_atxy(b
, x
- xd
* 2, y
- yd
* 2) == lcolor
)
385 /* ...or can't block where we need because of shortage
387 int libs1
= board_group_info(b
, group_atxy(b
, x
+ xd
- yd
* dd
, y
+ yd
- xd
* dd
)).libs
;
388 int libs2
= board_group_info(b
, group_atxy(b
, x
- xd
- yd
* dd
, y
- yd
- xd
* dd
)).libs
;
390 fprintf(stderr
, "libs1 %d libs2 %d\n", libs1
, libs2
);
391 if (libs1
< 2 && libs2
< 2)
393 if (board_atxy(b
, x
+ xd
* 2, y
+ yd
* 2) == lcolor
&& libs1
< 3)
395 if (board_atxy(b
, x
- xd
* 2, y
- yd
* 2) == lcolor
&& libs2
< 3)
400 /* This is very trivial and gets a lot of corner cases wrong.
401 * We need this to be just very fast. One important point is
402 * that we sometimes might not notice a ladder but if we do,
403 * it should always work; thus we can use this for strong
404 * negative hinting safely. */
406 is_middle_ladder(struct board
*b
, coord_t coord
, enum stone lcolor
)
408 int x
= coord_x(coord
, b
), y
= coord_y(coord
, b
);
410 /* Figure out the ladder direction */
412 xd
= board_atxy(b
, x
+ 1, y
) == S_NONE
? 1 : board_atxy(b
, x
- 1, y
) == S_NONE
? -1 : 0;
413 yd
= board_atxy(b
, x
, y
+ 1) == S_NONE
? 1 : board_atxy(b
, x
, y
- 1) == S_NONE
? -1 : 0;
417 fprintf(stderr
, "no ladder, too little space; self-atari?\n");
421 /* For given (xd,yd), we have two possibilities where to move
422 * next. Consider (-1,-1):
427 bool horiz_first
= ladder_catcher(b
, x
, y
- yd
, lcolor
); // left case
428 bool vert_first
= ladder_catcher(b
, x
- xd
, y
, lcolor
); // right case
430 /* We don't have to look at the other 'X' in the position - if it
431 * wouldn't be there, the group wouldn't be in atari. */
433 /* We do only tight ladders, not loose ladders. Furthermore,
434 * the ladders need to be simple:
436 * c O X supported . c O unsupported
439 assert(!(horiz_first
&& vert_first
));
440 if (!horiz_first
&& !vert_first
) {
441 /* TODO: In case of basic non-simple ladder, play out both variants. */
443 fprintf(stderr
, "non-simple ladder\n");
447 /* We do that below for further moves, but now initially - check
448 * that at 'c', we aren't putting any of the catching stones
450 #if 1 // this might be broken?
451 #define check_catcher_danger(b, x_, y_) do { \
452 if (board_atxy(b, (x_), (y_)) != S_OFFBOARD \
453 && board_group_info(b, group_atxy(b, (x_), (y_))).libs <= 2) { \
455 fprintf(stderr, "ladder failed - atari at the beginning\n"); \
460 check_catcher_danger(b
, x
, y
- yd
);
461 check_catcher_danger(b
, x
- xd
, y
+ yd
);
463 check_catcher_danger(b
, x
- xd
, y
);
464 check_catcher_danger(b
, x
+ xd
, y
- yd
);
466 #undef check_catcher_danger
469 #define ladder_check(xd1_, yd1_, xd2_, yd2_, xd3_, yd3_) \
470 if (board_atxy(b, x, y) != S_NONE) { \
471 /* Did we hit a stone when playing out ladder? */ \
472 if (ladder_catcher(b, x, y, lcolor)) \
473 return true; /* ladder works */ \
474 if (board_group_info(b, group_atxy(b, x, y)).lib[0] > 0) \
475 return false; /* friend that's not in atari himself */ \
477 /* No. So we are at new position. \
478 * We need to check indirect ladder breakers. */ \
480 * . x o O 1 <- only at O we can check for o at 2 \
481 * x o o x . otherwise x at O would be still deadly \
483 * We check for o and x at 1, these are vital. \
484 * We check only for o at 2; x at 2 would mean we \
485 * need to fork (one step earlier). */ \
486 coord_t c1 = coord_xy(b, x + (xd1_), y + (yd1_)); \
487 enum stone s1 = board_at(b, c1); \
488 if (s1 == lcolor) return false; \
489 if (s1 == stone_other(lcolor)) { \
490 /* One more thing - if the position at 3 is \
491 * friendly and safe, we escaped anyway! */ \
492 coord_t c3 = coord_xy(b, x + (xd3_), y + (yd3_)); \
493 return board_at(b, c3) != lcolor \
494 || board_group_info(b, group_at(b, c3)).libs < 2; \
496 enum stone s2 = board_atxy(b, x + (xd2_), y + (yd2_)); \
497 if (s2 == lcolor) return false; \
498 /* Then, can X actually "play" 1 in the ladder? */ \
499 if (neighbor_count_at(b, c1, lcolor) + neighbor_count_at(b, c1, S_OFFBOARD) >= 2) \
500 return false; /* It would be self-atari! */ \
502 #define ladder_horiz do { if (DEBUGL(6)) fprintf(stderr, "%d,%d horiz step (%d,%d)\n", x, y, xd, yd); x += xd; ladder_check(xd, 0, -2 * xd, yd, 0, yd); } while (0)
503 #define ladder_vert do { if (DEBUGL(6)) fprintf(stderr, "%d,%d vert step of (%d,%d)\n", x, y, xd, yd); y += yd; ladder_check(0, yd, xd, -2 * yd, xd, 0); } while (0)
505 if (ladder_catcher(b
, x
- xd
, y
, lcolor
))
515 board_stone_radar(struct board
*b
, coord_t coord
, int distance
)
518 coord_x(coord
, b
) - distance
,
519 coord_y(coord
, b
) - distance
,
520 coord_x(coord
, b
) + distance
,
521 coord_y(coord
, b
) + distance
523 for (int i
= 0; i
< 4; i
++)
526 else if (bounds
[i
] > board_size(b
) - 2)
527 bounds
[i
] = board_size(b
) - 2;
528 for (int x
= bounds
[0]; x
<= bounds
[2]; x
++)
529 for (int y
= bounds
[1]; y
<= bounds
[3]; y
++)
530 if (board_atxy(b
, x
, y
) != S_NONE
) {
531 /* fprintf(stderr, "radar %d,%d,%d: %d,%d (%d)\n",
532 coord_x(coord, b), coord_y(coord, b),
533 distance, x, y, board_atxy(b, x, y)); */
541 cfg_distances(struct board
*b
, coord_t start
, int *distances
, int maxdist
)
543 /* Queue for d+1 spots; no two spots of the same group
544 * should appear in the queue. */
545 #define qinc(x) (x = ((x + 1) >= board_size2(b) ? ((x) + 1 - board_size2(b)) : (x) + 1))
546 coord_t queue
[board_size2(b
)]; int qstart
= 0, qstop
= 0;
549 distances
[c
] = board_at(b
, c
) == S_OFFBOARD
? maxdist
+ 1 : -1;
552 queue
[qstop
++] = start
;
553 for (int d
= 0; d
<= maxdist
; d
++) {
554 /* Process queued moves, while setting the queue
556 int qa
= qstart
, qb
= qstop
;
558 for (int q
= qa
; q
< qb
; qinc(q
)) {
559 #define cfg_one(coord, grp) do {\
560 distances[coord] = d; \
561 foreach_neighbor (b, coord, { \
562 if (distances[c] < 0 && (!grp || group_at(b, coord) != grp)) { \
568 coord_t cq
= queue
[q
];
569 if (distances
[cq
] >= 0)
570 continue; /* We already looked here. */
571 if (board_at(b
, cq
) == S_NONE
) {
574 group_t g
= group_at(b
, cq
);
575 foreach_in_group(b
, g
) {
577 } foreach_in_group_end
;
584 if (distances
[c
] < 0)
585 distances
[c
] = maxdist
+ 1;
591 board_effective_handicap(struct board
*b
, int first_move_value
)
593 assert(b
->handicap
!= 1);
594 return (b
->handicap
? b
->handicap
: 1) * first_move_value
+ 0.5 - b
->komi
;
599 pass_is_safe(struct board
*b
, enum stone color
, struct move_queue
*mq
)
601 float score
= board_official_score(b
, mq
);
602 if (color
== S_BLACK
)
604 //fprintf(stderr, "%d score %f\n", color, score);
609 /* On average 25% of points remain empty at the end of a game */
610 #define EXPECTED_FINAL_EMPTY_PERCENT 25
612 /* Returns estimated number of remaining moves for one player until end of game. */
614 board_estimated_moves_left(struct board
*b
)
616 int total_points
= (board_size(b
)-2)*(board_size(b
)-2);
617 int moves_left
= (b
->flen
- total_points
*EXPECTED_FINAL_EMPTY_PERCENT
/100)/2;
618 return moves_left
> MIN_MOVES_LEFT
? moves_left
: MIN_MOVES_LEFT
;