advent-of-code/2022/day15.py

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# -*- encoding: utf-8 -*-
import sys
import numpy as np
import parse
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def part1(sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], row: int) -> int:
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no_beacons_row_l: list[np.ndarray] = []
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for (sx, sy), (bx, by) in sensor_to_beacon.items():
d = abs(sx - bx) + abs(sy - by) # closest
no_beacons_row_l.append(sx - np.arange(0, d - abs(sy - row) + 1))
no_beacons_row_l.append(sx + np.arange(0, d - abs(sy - row) + 1))
beacons_at_row = set(bx for (bx, by) in sensor_to_beacon.values() if by == row)
no_beacons_row = set(np.concatenate(no_beacons_row_l)).difference(beacons_at_row)
return len(no_beacons_row)
def part2_intervals(
sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
) -> tuple[int, int, int]:
from tqdm import trange
for y in trange(xy_max + 1):
its: list[tuple[int, int]] = []
for (sx, sy), (bx, by) in sensor_to_beacon.items():
d = abs(sx - bx) + abs(sy - by)
dx = d - abs(sy - y)
if dx >= 0:
its.append((max(0, sx - dx), min(sx + dx, xy_max)))
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its = sorted(its)
s, e = its[0]
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for si, ei in its[1:]:
if si > e + 1:
return si - 1, y, 4_000_000 * (si - 1) + y
if ei > e:
e = ei
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return (0, 0, 0)
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def part2_cplex(
sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
) -> tuple[int, int, int]:
from docplex.mp.model import Model
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m = Model()
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x, y = m.continuous_var_list(2, ub=xy_max, name=["x", "y"])
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for (sx, sy), (bx, by) in sensor_to_beacon.items():
d = abs(sx - bx) + abs(sy - by)
m.add_constraint(m.abs(x - sx) + m.abs(y - sy) >= d + 1, ctname=f"ct_{sx}_{sy}")
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m.set_objective("min", x + y)
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s = m.solve()
vx = int(s.get_value(x))
vy = int(s.get_value(y))
return vx, vy, 4_000_000 * vx + vy
lines = sys.stdin.read().splitlines()
sensor_to_beacon: dict[tuple[int, int], tuple[int, int]] = {}
for line in lines:
r = parse.parse(
"Sensor at x={sx}, y={sy}: closest beacon is at x={bx}, y={by}", line
)
sensor_to_beacon[int(r["sx"]), int(r["sy"])] = (int(r["bx"]), int(r["by"]))
xy_max = 4_000_000 if max(sensor_to_beacon) > (1_000, 0) else 20
row = 2_000_000 if max(sensor_to_beacon) > (1_000, 0) else 10
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print(f"answer 1 is {part1(sensor_to_beacon, row)}")
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# x, y, a2 = part2_cplex(sensor_to_beacon, xy_max)
x, y, a2 = part2_intervals(sensor_to_beacon, xy_max)
print(f"answer 2 is {a2} (x={x}, y={y})")