def main():
"""Skyscraper solver example."""
lattice = grilops.get_square_lattice(SIZE)
directions = {d.name: d for d in lattice.edge_sharing_directions()}
sg = grilops.SymbolGrid(lattice, SYM)
# Each row and each column contains each building height exactly once.
for y in range(SIZE):
sg.solver.add(Distinct(*[sg.grid[Point(y, x)] for x in range(SIZE)]))
for x in range(SIZE):
sg.solver.add(Distinct(*[sg.grid[Point(y, x)] for y in range(SIZE)]))
# We'll use the sightlines accumulator to keep track of a tuple storing:
# the tallest building we've seen so far
# the number of visible buildings we've encountered
Acc = Datatype("Acc") # pylint: disable=C0103
Acc.declare("acc", ("tallest", IntSort()), ("num_visible", IntSort()))
Acc = Acc.create() # pylint: disable=C0103
def accumulate(a, height):
return Acc.acc(
If(height > Acc.tallest(a), height, Acc.tallest(a)),
If(height > Acc.tallest(a),
Acc.num_visible(a) + 1, Acc.num_visible(a)))
for x, c in enumerate(GIVEN_TOP):
sg.solver.add(c == Acc.num_visible(
grilops.sightlines.reduce_cells(sg, Point(0, x), directions["S"],
Acc.acc(0, 0), accumulate)))
for y, c in enumerate(GIVEN_LEFT):
sg.solver.add(c == Acc.num_visible(
grilops.sightlines.reduce_cells(sg, Point(y, 0), directions["E"],
Acc.acc(0, 0), accumulate)))
for y, c in enumerate(GIVEN_RIGHT):
sg.solver.add(c == Acc.num_visible(
grilops.sightlines.reduce_cells(sg, Point(
y, SIZE - 1), directions["W"], Acc.acc(0, 0), accumulate)))
for x, c in enumerate(GIVEN_BOTTOM):
sg.solver.add(c == Acc.num_visible(
grilops.sightlines.reduce_cells(sg, Point(
SIZE - 1, x), directions["N"], Acc.acc(0, 0), accumulate)))
if sg.solve():
sg.print()
print()
if sg.is_unique():
print("Unique solution")
else:
print("Alternate solution")
sg.print()
else:
print("No solution")
def skyscraper(givens: Dict[Direction, List[int]]) -> str:
"""Solver for Skyscraper minipuzzles."""
sym = grilops.make_number_range_symbol_set(1, SIZE)
sg = grilops.SymbolGrid(LATTICE, sym)
shifter = Shifter(sg.solver)
# Each row and each column contains each building height exactly once.
for y in range(SIZE):
sg.solver.add(Distinct(*[sg.grid[Point(y, x)] for x in range(SIZE)]))
for x in range(SIZE):
sg.solver.add(Distinct(*[sg.grid[Point(y, x)] for y in range(SIZE)]))
# We'll use the sightlines accumulator to keep track of a tuple storing:
# the tallest building we've seen so far
# the number of visible buildings we've encountered
Acc = Datatype("Acc") # pylint: disable=C0103
Acc.declare("acc", ("tallest", IntSort()), ("num_visible", IntSort()))
Acc = Acc.create() # pylint: disable=C0103
def accumulate(a, height):
return Acc.acc(
If(height > Acc.tallest(a), height, Acc.tallest(a)),
If(height > Acc.tallest(a),
Acc.num_visible(a) + 1, Acc.num_visible(a)))
for d, gs in givens.items():
for i, g in enumerate(gs):
if d.vector.dy != 0:
g = g - shifter.col_shifts.get(i, 0)
p = Point(0 if d.vector.dy < 0 else SIZE - 1, i)
elif d.vector.dx != 0:
g = g - shifter.row_shifts.get(i, 0)
p = Point(i, 0 if d.vector.dx < 0 else SIZE - 1)
sg.solver.add(g == Acc.num_visible( # type: ignore[attr-defined]
grilops.sightlines.reduce_cells(
sg,
p,
LATTICE.opposite_direction(d),
Acc.acc(0, 0), # type: ignore[attr-defined]
accumulate)))
assert sg.solve()
sg.print()
print()
shifter.print_shifts()
print()
return shifter.eval_binary()
