static int
openregion(struct board_lib_state_struct *internal_state,
int i1, int i2, int j1, int j2)
{
int x, y;
if (i1 > i2)
return openregion(internal_state, i2, i1, j1, j2);
if (j1 > j2)
return openregion(internal_state, i1, i2, j2, j1);
/* Disregard parts of the region off the board. This is convenient
* in order not to have to special-case tiny boards. It also secures
* against potential reading outside the board[] array boundaries.
*/
if (i1 < 0)
i1 = 0;
if (j1 < 0)
j1 = 0;
if (i2 >= internal_state->board_size)
i2 = internal_state->board_size - 1;
if (j2 >= internal_state->board_size)
j2 = internal_state->board_size - 1;
for (x = i1; x <= i2; x++)
for (y = j1; y <= j2; y++)
if (BOARD(x, y) != EMPTY)
return 0;
return 1;
}
static int
openregion(int i1, int i2, int j1, int j2)
{
int x, y;
if (i1 > i2)
return openregion(i2, i1, j1, j2);
if (j1 > j2)
return openregion(i1, i2, j2, j1);
for (x = i1; x <= i2; x++)
for (y = j1; y <= j2; y++)
if (BOARD(x, y) != EMPTY)
return 0;
return 1;
}
int findpatn(int *i, int *j, int *val)
/* find pattern to match for next move */
{
int m, n;
int ti, tj, tval;
static int cnd, mtype; /* game tree node number, move type */
/* mtype = 0, basic; 1, inverted; 2, reflected; 3, inverted & reflected */
/* open game then occupy corners */
if (opn[4]) /* continue last move */
{
opn[4] = 0; /* clear flag */
if (opening(i, j, &cnd, mtype)) opn[4] = 1; /* more move then reset flag */
if (p[*i][*j] == EMPTY) /* valid move */
{
*val = 80;
return 1;
}
else
opn[4] = 0;
}
if (opn[0]) /* Northwest corner */
{
opn[0] = 0; /* clear flag */
if (openregion(0, 0, 5, 5))
{
cnd = 0;
mtype = 0;
opening(i, j, &cnd, mtype); /* get new node for next move */
if (opening(i, j, &cnd, mtype)) opn[4] = 1;
*val = 80;
return 1;
}
}
if (opn[1]) /* Southwest corner */
{
opn[1] = 0;
if (openregion(13, 0, 18, 5))
{
cnd = 0;
mtype = 1;
opening(i, j, &cnd, mtype); /* get new node for next move */
if (opening(i, j, &cnd, mtype)) opn[4] = 1;
*val = 80;
return 1;
}
}
if (opn[2]) /* Northeast corner */
{
opn[2] = 0;
if (openregion(0, 13, 5, 18))
{
cnd = 0;
mtype = 2;
opening(i, j, &cnd, mtype); /* get new node for next move */
if (opening(i, j, &cnd, mtype)) opn[4] = 1;
*val = 80;
return 1;
}
}
if (opn[3]) /* Northeast corner */
{
opn[3] = 0;
if (openregion(13, 13, 18, 18))
{
cnd = 0;
mtype = 3;
opening(i, j, &cnd, mtype); /* get new node for next move */
if (opening(i, j, &cnd, mtype)) opn[4] = 1;
*val = 80;
return 1;
}
}
/* occupy edges */
if (opn[5]) /* North edge */
{
opn[5] = 0;
if (openregion(0, 6, 4, 11))
{
*i = 3;
*j = 9;
*val = 80;
return 1;
}
}
if (opn[6]) /* South edge */
{
opn[6] = 0;
if (openregion(18, 6, 14, 11))
{
*i = 15;
*j = 9;
*val = 80;
return 1;
}
}
if (opn[7]) /* West edge */
{
opn[7] = 0;
if (openregion(6, 0, 11, 4))
{
*i = 9;
*j = 3;
*val = 80;
return 1;
}
}
if (opn[8]) /* East edge */
{
opn[8] = 0;
if (openregion(6, 18, 11, 14))
{
*i = 9;
*j = 15;
*val = 80;
return 1;
}
}
*i = -1;
*j = -1;
*val = -1;
/* find local pattern */
for (m = 0; m < 19; m++)
for (n = 0; n < 19; n++)
if ((p[m][n] == mymove) &&
(matchpat(m, n, &ti, &tj, &tval) && (tval > *val)))
{
*val = tval;
*i = ti;
*j = tj;
}
if (*val > 0) /* pattern found */
return 1;
else /* no match found */
return 0;
} /* end findpatn */
/* Generate move in empty corner or in middle of small board.*/
void
fuseki(int color)
{
int i = -1;
int j = -1;
int width; /* Side of the open region required in the corner. */
int empty_corner_value = EMPTY_CORNER_VALUE * board_size/19;
/* Return immediately if --disable_fuseki option used. */
if (disable_fuseki)
return;
set_symmetries();
/* Search in fuseki database unless disabled by --nofusekidb option. */
if (fusekidb && search_fuseki_database(color))
return;
/* On 9x9, only play open corners after the first move if nothing
* else useful is found.
*/
if (board_size == 9 && stones_on_board(color) > 0)
empty_corner_value = 5;
if (board_size <= 11) {
/* For boards of size 11x11 or smaller we first go for the center point. */
int middle = board_size/2;
if (openregion(middle-2, middle+2, middle-2, middle+2)) {
announce_move(POS(middle, middle), 45, color);
}
}
if (board_size < 9)
return;
if (board_size >= 18)
width = 8;
else if (board_size == 9)
width = 5;
else
width = board_size/2;
if (openregion(0, width-1, board_size-width, board_size-1)) {
choose_corner_move(UPPER_RIGHT, &i, &j);
announce_move(POS(i, j), empty_corner_value, color);
}
if (openregion(board_size-width, board_size-1, 0, width-1)) {
choose_corner_move(LOWER_LEFT, &i, &j);
announce_move(POS(i, j), empty_corner_value, color);
}
if (openregion(board_size-width, board_size-1,
board_size-width, board_size-1)) {
choose_corner_move(LOWER_RIGHT, &i, &j);
announce_move(POS(i, j), empty_corner_value, color);
}
if (openregion(0, width-1, 0, width-1)) {
choose_corner_move(UPPER_LEFT, &i, &j);
announce_move(POS(i, j), empty_corner_value, color);
}
}
