def solve_slitherlink(height, width, problem):
solver = Solver()
grid_frame = BoolGridFrame(solver, height, width)
solver.add_answer_key(grid_frame)
graph.active_edges_single_cycle(solver, grid_frame)
for y in range(height):
for x in range(width):
if problem[y][x] >= 0:
solver.ensure(
count_true(grid_frame.cell_neighbors(y, x)) == problem[y]
[x])
is_sat = solver.solve()
return is_sat, grid_frame
def solve_geradeweg(height, width, problem):
def line_length(edges):
edges = list(edges)
if len(edges) == 0:
return 0
ret = edges[-1].cond(1, 0)
for i in range(len(edges) - 2, -1, -1):
ret = edges[i].cond(1 + ret, 0)
return ret
solver = Solver()
grid_frame = BoolGridFrame(solver, height - 1, width - 1)
solver.add_answer_key(grid_frame)
is_passed = graph.active_edges_single_cycle(solver, grid_frame)
for y in range(height):
for x in range(width):
if problem[y][x] >= 1:
solver.ensure(is_passed[y, x])
solver.ensure(fold_or(([grid_frame.horizontal[y, x - 1]] if x > 0 else []) + ([grid_frame.horizontal[y, x]] if x < width - 1 else [])).then(
line_length(reversed(list(grid_frame.horizontal[y, :x]))) + line_length(grid_frame.horizontal[y, x:]) == problem[y][x]
))
solver.ensure(fold_or(([grid_frame.vertical[y - 1, x]] if y > 0 else []) + ([grid_frame.vertical[y, x]] if y < height - 1 else [])).then(
line_length(reversed(list(grid_frame.vertical[:y, x]))) + line_length(grid_frame.vertical[y:, x]) == problem[y][x]
))
is_sat = solver.solve()
return is_sat, grid_frame
def _add_constraints(self, roots):
solver = self.solver
height = self.height
width = self.width
region_id = self.region_id
rank = IntGrid(solver, height, width, low=0, high=height * width - 1)
is_root = BoolGrid(solver, height, width)
spanning_forest = BoolGridFrame(solver, height - 1, width - 1)
for y in range(height):
for x in range(width):
neighbors = []
if y > 0:
neighbors.append((y - 1, x))
if y < height - 1:
neighbors.append((y + 1, x))
if x > 0:
neighbors.append((y, x - 1))
if x < width - 1:
neighbors.append((y, x + 1))
solver.ensure(
sum([(spanning_forest[y + y2, x + x2]
& (rank[y, x] > rank[y2, x2])).cond(1, 0)
for y2, x2 in neighbors]) == is_root[y, x].cond(0, 1))
if y > 0:
solver.ensure(spanning_forest[y * 2 - 1, x * 2].then(
(region_id[y, x] == region_id[y - 1, x])
& (rank[y, x] != rank[y - 1, x])))
if x > 0:
solver.ensure(spanning_forest[y * 2, x * 2 - 1].then(
(region_id[y, x] == region_id[y, x - 1])
& (rank[y, x] != rank[y, x - 1])))
for i in range(self.num_regions):
solver.ensure(
sum([(r & (n == i)).cond(1, 0)
for r, n in zip(is_root[:, :], region_id[:, :])]) == 1)
if roots is not None:
for i, (y, x) in enumerate(roots):
solver.ensure(region_id[y, x] == i)
solver.ensure(is_root[y, x])
def solve_masyu(height, width, problem):
solver = Solver()
grid_frame = BoolGridFrame(solver, height - 1, width - 1)
solver.add_answer_key(grid_frame)
graph.active_edges_single_cycle(solver, grid_frame)
def get_edge(y, x, neg=False):
if 0 <= y <= 2 * (height - 1) and 0 <= x <= 2 * (width - 1):
if y % 2 == 0:
r = grid_frame.horizontal[y // 2][x // 2]
else:
r = grid_frame.vertical[y // 2][x // 2]
if neg:
return ~r
else:
return r
else:
return neg
for y in range(height):
for x in range(width):
if problem[y][x] == 1:
solver.ensure(
(get_edge(y * 2, x * 2 - 1) & get_edge(y * 2, x * 2 + 1)
& (get_edge(y * 2, x * 2 - 3, True)
| get_edge(y * 2, x * 2 + 3, True)))
| (get_edge(y * 2 - 1, x * 2) & get_edge(y * 2 + 1, x * 2)
& (get_edge(y * 2 - 3, x * 2, True)
| get_edge(y * 2 + 3, x * 2, True))))
elif problem[y][x] == 2:
dirs = [
get_edge(y * 2, x * 2 - 1) & get_edge(y * 2, x * 2 - 3),
get_edge(y * 2 - 1, x * 2) & get_edge(y * 2 - 3, x * 2),
get_edge(y * 2, x * 2 + 1) & get_edge(y * 2, x * 2 + 3),
get_edge(y * 2 + 1, x * 2) & get_edge(y * 2 + 3, x * 2),
]
solver.ensure((dirs[0] | dirs[2]) & (dirs[1] | dirs[3]))
is_sat = solver.solve()
return is_sat, grid_frame
def solve_yajilin(height, width, problem):
solver = Solver()
grid_frame = BoolGridFrame(solver, height - 1, width - 1)
is_passed = graph.active_edges_single_cycle(solver, grid_frame)
black_cell = solver.bool_array((height, width))
graph.active_vertices_not_adjacent(solver, black_cell)
solver.add_answer_key(grid_frame)
solver.add_answer_key(black_cell)
for y in range(height):
for x in range(width):
if problem[y][x] != '..':
# clue
solver.ensure(~is_passed[y, x])
solver.ensure(~black_cell[y, x])
if problem[y][x][0] == '^':
solver.ensure(
count_true(black_cell[0:y,
x]) == int(problem[y][x][1:]))
elif problem[y][x][0] == 'v':
solver.ensure(
count_true(black_cell[(y + 1):height,
x]) == int(problem[y][x][1:]))
elif problem[y][x][0] == '<':
solver.ensure(
count_true(black_cell[y,
0:x]) == int(problem[y][x][1:]))
elif problem[y][x][0] == '>':
solver.ensure(
count_true(black_cell[y, (
x + 1):width]) == int(problem[y][x][1:]))
else:
solver.ensure(is_passed[y, x] != black_cell[y, x])
is_sat = solver.solve()
return is_sat, grid_frame, black_cell
def solve_slalom(height,
width,
origin,
is_black,
gates,
reference_sol_loop=None):
solver = Solver()
loop = BoolGridFrame(solver, height - 1, width - 1)
loop_dir = BoolGridFrame(solver, height - 1, width - 1)
solver.add_answer_key(loop.all_edges())
graph.active_edges_single_cycle(solver, loop)
gate_ord = solver.int_array((height, width), 0, len(gates))
passed = solver.bool_array((height, width))
gate_id = [[None for _ in range(width)] for _ in range(height)]
for y, x, d, l, n in gates:
if d == 0: # horizontal
gate_cells = [(y, x + i) for i in range(l)]
elif d == 1: # vertical
gate_cells = [(y + i, x) for i in range(l)]
for y2, x2 in gate_cells:
gate_id[y2][x2] = n
solver.ensure(
count_true([passed[y2, x2] for y2, x2 in gate_cells]) == 1)
solver.ensure(passed[origin])
for y in range(height):
for x in range(width):
neighbors = []
if y > 0:
neighbors.append((y - 1, x))
if y < height - 1:
neighbors.append((y + 1, x))
if x > 0:
neighbors.append((y, x - 1))
if x < width - 1:
neighbors.append((y, x + 1))
# in-degree, out-degree
solver.ensure(
count_true([
loop[y + y2, x + x2]
& (loop_dir[y + y2, x + x2] != ((y2, x2) < (y, x)))
for y2, x2 in neighbors
]) == passed[y, x].cond(1, 0))
solver.ensure(
count_true([
loop[y + y2, x + x2]
& (loop_dir[y + y2, x + x2] == ((y2, x2) < (y, x)))
for y2, x2 in neighbors
]) == passed[y, x].cond(1, 0))
if is_black[y][x]:
solver.ensure(~passed[y, x])
continue
if (y, x) == origin:
continue
if gate_id[y][x] is None:
for y2, x2 in neighbors:
solver.ensure((loop[y + y2, x + x2] &
(loop_dir[y + y2, x + x2] !=
((y2, x2) < (y, x)))).then(
(gate_ord[y2, x2] == gate_ord[y, x])))
else:
for y2, x2 in neighbors:
solver.ensure((loop[y + y2, x + x2] &
(loop_dir[y + y2, x + x2] !=
((y2, x2) < (y, x)))).then(
(gate_ord[y2,
x2] == gate_ord[y, x] - 1)))
if gate_id[y][x] >= 1:
solver.ensure(passed[y,
x].then(gate_ord[y,
x] == gate_id[y][x]))
# auxiliary constraint
for y0 in range(height):
for x0 in range(width):
for y1 in range(height):
for x1 in range(width):
if (y0, x0) < (y1, x1) and gate_id[y0][
x0] is not None and gate_id[y1][x1] is not None:
solver.ensure((passed[y0, x0] & passed[y1, x1]).then(
gate_ord[y0, x0] != gate_ord[y1, x1]))
if reference_sol_loop is not None:
avoid_reference_sol = []
for y in range(height):
for x in range(width):
if y < height - 1:
avoid_reference_sol.append(
loop.vertical[y,
x] != reference_sol_loop.vertical[y,
x].sol)
if x < width - 1:
avoid_reference_sol.append(loop.horizontal[
y, x] != reference_sol_loop.horizontal[y, x].sol)
solver.ensure(fold_or(avoid_reference_sol))
is_sat = solver.find_answer()
return is_sat, loop
else:
is_sat = solver.solve()
return is_sat, loop
def generate_slalom_initial_placement(height,
width,
n_min_gates=None,
n_max_gates=None,
n_max_isolated_black_cells=None,
no_adjacent_black_cell=False,
no_facing_length_two=False,
no_space_2x2=False,
black_cell_in_every_3x3=False,
min_go_through=0):
solver = Solver()
loop = BoolGridFrame(solver, height - 1, width - 1)
is_black = solver.bool_array((height, width))
is_horizontal = solver.bool_array((height, width))
is_vertical = solver.bool_array((height, width))
solver.ensure(~(is_black & is_horizontal))
solver.ensure(~(is_black & is_vertical))
solver.ensure(~(is_horizontal & is_vertical))
solver.ensure(~(is_horizontal[0, :]))
solver.ensure(~(is_horizontal[-1, :]))
solver.ensure(~(is_vertical[:, 0]))
solver.ensure(~(is_vertical[:, -1]))
is_passed = graph.active_edges_single_cycle(solver, loop)
# --------- board must be valid as a problem ---------
# loop constraints
for y in range(height):
for x in range(width):
if y > 0:
solver.ensure(is_black[y, x].then(~loop.vertical[y - 1, x]))
solver.ensure(is_vertical[y, x].then(~loop.vertical[y - 1, x]))
if y < height - 1:
solver.ensure(is_black[y, x].then(~loop.vertical[y, x]))
solver.ensure(is_vertical[y, x].then(~loop.vertical[y, x]))
if x > 0:
solver.ensure(is_black[y, x].then(~loop.horizontal[y, x - 1]))
solver.ensure(
is_horizontal[y, x].then(~loop.horizontal[y, x - 1]))
if x < width - 1:
solver.ensure(is_black[y, x].then(~loop.horizontal[y, x]))
solver.ensure(is_horizontal[y, x].then(~loop.horizontal[y, x]))
# gates must be closed
solver.ensure(is_vertical[1:, :].then(is_vertical[:-1, :]
| is_black[:-1, :]))
solver.ensure(is_vertical[:-1, :].then(is_vertical[1:, :]
| is_black[1:, :]))
solver.ensure(is_horizontal[:, 1:].then(is_horizontal[:, :-1]
| is_black[:, :-1]))
solver.ensure(is_horizontal[:, :-1].then(is_horizontal[:, 1:]
| is_black[:, 1:]))
# each horizontal gate must be passed exactly once
for y in range(1, height - 1):
for x in range(width):
on_loop = []
for x2 in range(width):
cond = [is_passed[y, x2]]
if x2 < x:
cond += [is_horizontal[y, i] for i in range(x2, x)]
elif x < x2:
cond += [is_horizontal[y, i] for i in range(x + 1, x2 + 1)]
on_loop.append(fold_and(cond))
solver.ensure(is_horizontal[y, x].then(count_true(on_loop) == 1))
# each vertical gate must be passed exactly once
for y in range(height):
for x in range(1, width - 1):
on_loop = []
for y2 in range(width):
cond = [is_passed[y2, x]]
if y2 < y:
cond += [is_vertical[i, x] for i in range(y2, y)]
elif y < y2:
cond += [is_vertical[i, x] for i in range(y + 1, y2 + 1)]
on_loop.append(fold_and(cond))
solver.ensure(is_vertical[y, x].then(count_true(on_loop) == 1))
# --------- loop must be canonical ---------
# for simplicity, no stacked gates (although this is not necessary for the canonicity)
solver.ensure(~(is_horizontal[:-1, :] & is_horizontal[1:, :]))
solver.ensure(~(is_vertical[:, :-1] & is_vertical[:, 1:]))
for y in range(height):
for x in range(width):
if 0 < y < height - 1:
if x == 0 or x == width - 1:
solver.ensure(is_horizontal[y,
x].then(~is_black[y - 1, x]
& ~is_black[y + 1, x]))
else:
solver.ensure((is_horizontal[y, x] &
(is_black[y - 1, x] | is_black[y + 1, x])
).then(is_horizontal[y, x - 1]
& is_horizontal[y, x + 1]
& ~is_black[y - 1, x - 1]
& ~is_black[y + 1, x - 1]
& ~is_black[y + 1, x - 1]
& ~is_black[y + 1, x + 1]))
if 0 < x < width - 1:
if y == 0 or y == height - 1:
solver.ensure(is_vertical[y,
x].then(~is_black[y, x - 1]
& ~is_black[y, x + 1]))
else:
solver.ensure(
(is_vertical[y, x] &
(is_black[y, x - 1] | is_black[y, x + 1])
).then(is_vertical[y - 1, x] & is_vertical[y + 1, x]
& ~is_black[y - 1, x - 1]
& ~is_black[y + 1, x - 1]
& ~is_black[y + 1, x - 1]
& ~is_black[y + 1, x + 1]))
# no detour
for y in range(height - 1):
for x in range(width - 1):
solver.ensure(count_true(loop.cell_neighbors(y, x)) <= 2)
solver.ensure(
fold_and(~is_black[y:y + 2, x:x + 2],
~is_horizontal[y:y + 2, x:x + 2],
~is_vertical[y:y + 2, x:x + 2]).then(
count_true(loop.cell_neighbors(y, x)) +
1 < count_true(is_passed[y:y + 2, x:x + 2])))
# no ambiguous L-shaped turning
for y in range(height - 1):
for x in range(width - 1):
for dy in [0, 1]:
for dx in [0, 1]:
solver.ensure(~fold_and([
loop.horizontal[y + dy, x], loop.vertical[
y, x + dx], ~is_vertical[y + dy, x + 1 - dx],
~is_horizontal[y + 1 - dx, x +
dx], ~is_black[y + 1 - dy, x + 1 - dx],
count_true(is_passed[y:y + 2, x:x + 2]) == 3
]))
# no ambiguous L-shaped turning involving gates
for y in range(height - 1):
for x in range(width - 2):
solver.ensure(
fold_and(
is_vertical[y:y + 2, x + 1],
~is_black[y:y + 2, x:x + 3]).then(
count_true(loop.horizontal[y, x], loop.horizontal[
y + 1,
x], loop.vertical[y, x], loop.vertical[y, x + 2]) +
1 < count_true(is_passed[y:y + 2,
x], is_passed[y:y + 2,
x + 2])))
for y in range(height - 2):
for x in range(width - 1):
solver.ensure(
fold_and(is_horizontal[y + 1, x:x + 2],
~is_black[y:y + 3, x:x + 2]).
then(
count_true(loop.vertical[y, x], loop.vertical[y, x + 1],
loop.horizontal[y, x], loop.horizontal[y + 2,
x]) +
1 < count_true(is_passed[y, x:x + 2], is_passed[y + 2,
x:x + 2])))
# no dead ends
for y in range(height):
for x in range(width):
solver.ensure((~is_black[y, x]).then(
count_true(~is_black.four_neighbors(y, x)) >= 2))
# --------- avoid "trivial" problems ---------
solver.ensure(count_true(is_vertical) > 5)
solver.ensure(count_true(is_horizontal) > 4)
if n_max_isolated_black_cells is not None:
lonely_black_cell = []
for y in range(height):
for x in range(width):
cond = [is_black[y, x]]
if y > 0:
cond.append(~is_vertical[y - 1, x])
if y < height - 1:
cond.append(~is_vertical[y + 1, x])
if x > 0:
cond.append(~is_horizontal[y, x - 1])
if x < width - 1:
cond.append(~is_horizontal[y, x + 1])
lonely_black_cell.append(fold_and(cond))
solver.ensure(
count_true(lonely_black_cell) <= n_max_isolated_black_cells)
short_gates = []
for y in range(height):
for x in range(width):
g1 = fold_and([
is_vertical[y, x], ~is_vertical[y - 1, x] if y > 0 else True,
~is_vertical[y + 1, x] if y < height - 1 else True
])
g2 = fold_and([
is_horizontal[y,
x], ~is_horizontal[y, x - 1] if x > 0 else True,
~is_horizontal[y, x + 1] if x < width - 1 else True
])
if 0 < y < height - 1 and 0 < x < width - 1:
short_gates.append(g1)
short_gates.append(g2)
solver.ensure((g1 | g2).then(~is_black[y - 1, x - 1]
& ~is_black[y - 1, x + 1]
& ~is_black[y + 1, x - 1]
& ~is_black[y + 1, x + 1]))
else:
solver.ensure(~g1)
solver.ensure(~g2)
solver.ensure(count_true(short_gates) <= 0)
for y in range(1, height - 1):
for x in range(1, width - 1):
solver.ensure(
count_true(
is_horizontal[y - 1, x] & is_black[y - 1, x - 1]
& is_black[y - 1, x + 1],
is_horizontal[y + 1, x] & is_black[y + 1, x - 1]
& is_black[y + 1, x + 1],
is_vertical[y, x - 1] & is_black[y - 1, x - 1]
& is_black[y + 1, x - 1],
is_vertical[y, x + 1] & is_black[y - 1, x + 1]
& is_black[y + 1, x + 1],
) <= 1)
# --------- ensure randomness ---------
passed_constraints = [[0 for _ in range(width)] for _ in range(height)]
for y in range(height):
for x in range(width):
if (y > 0 and passed_constraints[y - 1][x] != 0) or (
x > 0 and passed_constraints[y][x - 1] != 0):
continue
passed_constraints[y][x] = max(0, random.randint(-20, 2))
for y in range(height):
for x in range(width):
if passed_constraints[y][x] == 1:
solver.ensure(is_passed[y, x])
elif passed_constraints[y][x] == 2:
solver.ensure(~is_passed[y, x])
# --------- extra constraints ---------
if n_min_gates is not None or n_max_gates is not None:
gate_representative = []
for y in range(height):
for x in range(width):
gate_representative.append(is_horizontal[y, x] & (
~is_horizontal[y, x - 1] if x > 0 else True))
gate_representative.append(is_vertical[y, x] & (
~is_vertical[y - 1, x] if y > 0 else True))
if n_min_gates is not None:
solver.ensure(n_min_gates <= count_true(gate_representative))
if n_max_gates is not None:
solver.ensure(count_true(gate_representative) <= n_max_gates)
if min_go_through > 0:
go_through = []
for y in range(height):
for x in range(width):
if y < height - 4 and 0 < x < width - 1:
go_through.append(
fold_and(
is_horizontal[y + 1,
x], is_horizontal[y + 1, x - 1]
| is_horizontal[y + 1, x + 1],
~is_black[y + 2, x - 1], ~is_black[y + 2, x + 1],
is_horizontal[y + 3,
x], is_horizontal[y + 3, x - 1]
| is_horizontal[y + 3, x + 1],
loop.vertical[y:y + 4, x]))
if x < width - 4 and 0 < y < height - 1:
go_through.append(
fold_and(
is_vertical[y, x + 1], is_vertical[y - 1, x + 1]
| is_vertical[y + 1, x + 1],
~is_black[y - 1, x + 2], ~is_black[y + 1, x + 2],
is_vertical[y, x + 3], is_vertical[y - 1, x + 3]
| is_vertical[y + 1, x + 3],
loop.horizontal[y, x:x + 4]))
solver.ensure(count_true(go_through) >= 2)
if no_adjacent_black_cell:
solver.ensure(~(is_black[:-1, :] & is_black[1:, :]))
solver.ensure(~(is_black[:, :-1] & is_black[:, 1:]))
solver.ensure(~(is_black[:-1, :-1] & is_black[1:, 1:]))
solver.ensure(~(is_black[:-1, 1:] & is_black[1:, :-1]))
if no_facing_length_two:
for y in range(height):
for x in range(width):
if y <= height - 3 and x <= width - 4:
solver.ensure(~fold_and(
is_black[y, x], is_black[y + 2, x], is_black[y, x + 3],
is_black[y + 2, x + 3], is_horizontal[
y, x + 1], is_horizontal[y, x + 2], is_horizontal[
y + 2, x + 1], is_horizontal[y + 2, x + 2]))
if y <= height - 4 and x <= width - 3:
solver.ensure(
~fold_and(is_black[y, x], is_black[y, x + 2], is_black[
y + 3, x], is_black[y + 3, x + 2], is_vertical[
y + 1, x], is_vertical[y + 2, x], is_vertical[
y + 1, x + 2], is_vertical[y + 2, x + 2]))
if no_space_2x2:
has_some = is_black | is_vertical | is_horizontal
solver.ensure(has_some[:-1, :-1] | has_some[1:, :-1]
| has_some[:-1, 1:] | has_some[1:, 1:])
if black_cell_in_every_3x3:
for y in range(-1, height - 2):
for x in range(-1, width - 2):
solver.ensure(
fold_or(is_black[max(0, y):min(height, y + 3),
max(0, x):min(width, x + 3)]))
is_sat = solver.find_answer()
if not is_sat:
return None
return loop, is_passed, is_black, is_horizontal, is_vertical
def solve_firefly(height, width, problem):
solver = Solver()
has_line = BoolGridFrame(solver, height - 1, width - 1)
solver.add_answer_key(has_line)
line_ul = BoolGridFrame(solver, height - 1, width - 1)
line_dr = BoolGridFrame(solver, height - 1, width - 1)
solver.ensure(
Array(list(has_line)) == (Array(list(line_ul)) | Array(list(line_dr))))
solver.ensure(~(Array(list(line_ul)) & Array(list(line_dr))))
# unicyclic (= connected)
ignored_edge = BoolGridFrame(solver, height - 1, width - 1)
solver.ensure(count_true(ignored_edge) == 1)
rank = solver.int_array((height, width), 0, height * width - 1)
solver.ensure(
(line_ul.horizontal
& ~ignored_edge.horizontal).then(rank[:, :-1] < rank[:, 1:]))
solver.ensure((line_ul.vertical
& ~ignored_edge.vertical).then(rank[:-1, :] < rank[1:, :]))
solver.ensure(
(line_dr.horizontal
& ~ignored_edge.horizontal).then(rank[:, :-1] > rank[:, 1:]))
solver.ensure((line_dr.vertical
& ~ignored_edge.vertical).then(rank[:-1, :] > rank[1:, :]))
max_n_turn = 0
for y in range(height):
for x in range(width):
if problem[y][x][0] != '.' and problem[y][x][1] != '?':
max_n_turn = max(max_n_turn, int(problem[y][x][1:]))
n_turn_unknown = max_n_turn + 1
n_turn_horizontal = solver.int_array((height, width - 1), 0,
max_n_turn + 1)
n_turn_vertical = solver.int_array((height - 1, width), 0, max_n_turn + 1)
for y in range(height):
for x in range(width):
# u, d, l, r
adj = [] # (line_in, line_out, # turn)
if y > 0:
adj.append((line_dr.vertical[y - 1, x],
line_ul.vertical[y - 1, x], n_turn_vertical[y - 1,
x]))
else:
adj.append(None)
if y < height - 1:
adj.append((line_ul.vertical[y, x], line_dr.vertical[y, x],
n_turn_vertical[y, x]))
else:
adj.append(None)
if x > 0:
adj.append(
(line_dr.horizontal[y, x - 1],
line_ul.horizontal[y, x - 1], n_turn_horizontal[y,
x - 1]))
else:
adj.append(None)
if x < width - 1:
adj.append((line_ul.horizontal[y, x], line_dr.horizontal[y, x],
n_turn_horizontal[y, x]))
else:
adj.append(None)
if problem[y][x][0] != '.':
if problem[y][x][0] == '^':
out_idx = 0
elif problem[y][x][0] == 'v':
out_idx = 1
elif problem[y][x][0] == '<':
out_idx = 2
elif problem[y][x][0] == '>':
out_idx = 3
else:
raise ValueError('invalid direction: {}'.format(
problem[y][x][0]))
if adj[out_idx] is None:
solver.ensure(False)
break
solver.ensure(adj[out_idx][1])
if problem[y][x][1] != '?':
solver.ensure(adj[out_idx][2] == int(problem[y][x][1:]))
else:
solver.ensure(adj[out_idx][2] == n_turn_unknown)
for i in range(4):
if adj[i] is not None and i != out_idx:
solver.ensure(~adj[i][1])
solver.ensure(
adj[i][0].then((adj[i][2] == 0)
| (adj[i][2] == n_turn_unknown)))
else:
adj_present = list(filter(lambda x: x is not None, adj))
solver.ensure(
count_true(map(lambda x: x[0], adj_present)) <= 1)
solver.ensure(
count_true(map(lambda x: x[0], adj_present)) == count_true(
map(lambda x: x[1], adj_present)))
for i in range(4):
for j in range(4):
if adj[i] is not None and adj[j] is not None and i != j:
if (i // 2) == (j // 2): # straight
solver.ensure(
(adj[i][0]
& adj[j][1]).then(adj[i][2] == adj[j][2]))
else:
solver.ensure(
(adj[i][0] & adj[j][1]
).then(((adj[i][2] == n_turn_unknown)
& (adj[j][2] == n_turn_unknown))
| (adj[i][2] == adj[j][2] + 1)))
is_sat = solver.solve()
return is_sat, has_line