pachi_py/pachi/tactics/util.c

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#define DEBUG
#include "board.h"
#include "debug.h"
#include "tactics/util.h"


bool
board_stone_radar(struct board *b, coord_t coord, int distance)
{
	int bounds[4] = {
		coord_x(coord, b) - distance,
		coord_y(coord, b) - distance,
		coord_x(coord, b) + distance,
		coord_y(coord, b) + distance
	};
	for (int i = 0; i < 4; i++)
		if (bounds[i] < 1)
			bounds[i] = 1;
		else if (bounds[i] > board_size(b) - 2)
			bounds[i] = board_size(b) - 2;
	for (int x = bounds[0]; x <= bounds[2]; x++)
		for (int y = bounds[1]; y <= bounds[3]; y++)
			if (board_atxy(b, x, y) != S_NONE) {
				/* fprintf(stderr, "radar %d,%d,%d: %d,%d (%d)\n",
					coord_x(coord, b), coord_y(coord, b),
					distance, x, y, board_atxy(b, x, y)); */
				return true;
			}
	return false;
}


void
cfg_distances(struct board *b, coord_t start, int *distances, int maxdist)
{
	/* Queue for d+1 spots; no two spots of the same group
	 * should appear in the queue. */
#define qinc(x) (x = ((x + 1) >= board_size2(b) ? ((x) + 1 - board_size2(b)) : (x) + 1))
	coord_t queue[board_size2(b)]; int qstart = 0, qstop = 0;

	foreach_point(b) {
		distances[c] = board_at(b, c) == S_OFFBOARD ? maxdist + 1 : -1;
	} foreach_point_end;

	queue[qstop++] = start;
	for (int d = 0; d <= maxdist; d++) {
		/* Process queued moves, while setting the queue
		 * for new wave. */
		int qa = qstart, qb = qstop;
		qstart = qstop;
		for (int q = qa; q < qb; qinc(q)) {
#define cfg_one(coord, grp) do {\
	distances[coord] = d; \
	foreach_neighbor (b, coord, { \
		if (distances[c] < 0 && (!grp || group_at(b, coord) != grp)) { \
			queue[qstop] = c; \
			qinc(qstop); \
		} \
	}); \
} while (0)
			coord_t cq = queue[q];
			if (distances[cq] >= 0)
				continue; /* We already looked here. */
			if (board_at(b, cq) == S_NONE) {
				cfg_one(cq, 0);
			} else {
				group_t g = group_at(b, cq);
				foreach_in_group(b, g) {
					cfg_one(c, g);
				} foreach_in_group_end;
			}
#undef cfg_one
		}
	}

	foreach_point(b) {
		if (distances[c] < 0)
			distances[c] = maxdist + 1;
	} foreach_point_end;
}


floating_t
board_effective_handicap(struct board *b, int first_move_value)
{
	/* This can happen if the opponent passes during handicap
	 * placing phase. */
	// assert(b->handicap != 1);

	/* Always return 0 for even games, in particular if
	 * first_move_value is set on purpose to a value different
	 * from the correct theoretical value (2*komi). */
	if (!b->handicap)
		return b->komi == 0.5 ? 0.5 * first_move_value : 7.5 - b->komi;
	return b->handicap * first_move_value + 0.5 - b->komi;
}


bool
pass_is_safe(struct board *b, enum stone color, struct move_queue *mq)
{
	floating_t score = board_official_score(b, mq);
	if (color == S_BLACK)
		score = -score;
	//fprintf(stderr, "%d score %f\n", color, score);
	return (score >= 0);
}


/* On average 20% of points remain empty at the end of a game */
#define EXPECTED_FINAL_EMPTY_PERCENT 20

/* Returns estimated number of remaining moves for one player until end of game. */
int
board_estimated_moves_left(struct board *b)
{
	int total_points = (board_size(b)-2)*(board_size(b)-2);
	int moves_left = (b->flen - total_points*EXPECTED_FINAL_EMPTY_PERCENT/100)/2;
	return moves_left > MIN_MOVES_LEFT ? moves_left : MIN_MOVES_LEFT;
}