static bool
test_can_countercapture(struct board *b, char *arg)
{
coord_t c = str2scoord(arg, board_size(b));
arg += strcspn(arg, " ") + 1;
int eres = atoi(arg);
board_print_test(2, b);
if (DEBUGL(1))
printf("can_countercap %s %d...\t", coord2sstr(c, b), eres);
enum stone color = board_at(b, c);
group_t g = group_at(b, c);
assert(color == S_BLACK || color == S_WHITE);
int rres = can_countercapture(b, g, NULL, 0);
if (rres == eres) {
if (DEBUGL(1))
printf("OK\n");
} else {
if (debug_level <= 2) {
board_print_test(0, b);
printf("can_countercap %s %d...\t", coord2sstr(c, b), eres);
}
printf("FAILED (%d)\n", rres);
}
return rres == eres;
}
bool
is_middle_ladder(Board *b, Coord coord, group_t laddered, Stone lcolor)
{
/* TODO: Remove the redundant parameters. */
assert(group_at(b, laddered)->liberties == 1);
Coord last_lib = get_nlibs_of_group(b, laddered, 1, NULL);
assert(last_lib == coord);
assert(group_at(b, laddered)->color == lcolor);
/* If we can move into empty space or do not have enough space
* to escape, this is obviously not a ladder. */
if (immediate_liberty_count(b, coord) != 2) {
/*
if (DEBUGL(5))
fprintf(stderr, "no ladder, wrong free space\n");
*/
return false;
}
/* A fair chance for a ladder. Group in atari, with some but limited
* space to escape. Time for the expensive stuff - set up a temporary
* board and start selective 2-liberty search. */
Board *bset = (Board *)malloc(BOARD_MAX_SIZE * 2 * sizeof(Board));
struct move_queue ccq = { .moves = 0 };
if (can_countercapture(b, lcolor, laddered, lcolor, &ccq, 0)) {
/* We could escape by countercapturing a group.
* Investigate. */
assert(ccq.moves > 0);
for (unsigned int i = 0; i < ccq.moves; i++) {
Board b2;
CopyBoard(&b2, b);
bool is_ladder = middle_ladder_walk(&b2, bset, laddered, ccq.move[i], lcolor);
// board_done_noalloc(&b2);
if (!is_ladder) {
free(bset);
return false;
}
}
}
Board b2;
CopyBoard(&b2, b);
Coord last_lib2 = get_nlibs_of_group(&b2, laddered, 1, NULL);
bool is_ladder = middle_ladder_walk(&b2, bset, laddered, last_lib2, lcolor);
// board_done_noalloc(&b2);
free(bset);
return is_ladder;
}
bool
wouldbe_ladder(Board *b, group_t group, Coord escapelib, Coord chaselib, Stone lcolor)
{
assert(b->_groups[group].liberties == 2);
assert(b->_groups[group].color == lcolor);
/*
if (DEBUGL(6))
fprintf(stderr, "would-be ladder check - does %s %s play out chasing move %s?\n",
stone2str(lcolor), coord2sstr(escapelib, b), coord2sstr(chaselib, b));
*/
if (!NEIGHBOR8(escapelib, chaselib)) {
/*
if (DEBUGL(5))
fprintf(stderr, "cannot determine ladder for remote simulated stone\n");
*/
return false;
}
if (neighbor_count_at(b, chaselib, lcolor) != 1 || immediate_liberty_count(b, chaselib) != 2) {
/*
if (DEBUGL(5))
fprintf(stderr, "overly trivial for a ladder\n");
*/
return false;
}
bool is_ladder = false;
Board *bset = (Board *)malloc(BOARD_MAX_SIZE * 2 * sizeof(Board));
Board b2;
CopyBoard(&b2, b);
GroupId4 ids;
if (TryPlay(&b2, X(chaselib), Y(chaselib), OPPONENT(lcolor), &ids)) {
Play(&b2, &ids);
Coord last_lib2 = get_nlibs_of_group(&b2, group, 1, NULL);
is_ladder = middle_ladder_walk(&b2, bset, group, last_lib2, lcolor);
}
// board_done_noalloc(&b2);
free(bset);
return is_ladder;
}
