[2022][ruby][15.x]

pull/1/head
Alpha Chen 2 years ago
parent 4129a82f26
commit da36d561b8
Signed by: alpha
SSH Key Fingerprint: SHA256:3fOT8fiYQG/aK9ntivV3Bqtg8AYQ7q4nV6ZgihOA20g

@ -0,0 +1,87 @@
require "set"
sensors_and_beacons = ARGF.read
.scan(/Sensor at x=(-?\d+), y=(-?\d+): closest beacon is at x=(-?\d+), y=(-?\d+)/)
.map { _1.map(&:to_i) }
.flatten
.each_slice(2)
# part one
row = 2_000_000
# row = 10
no_beacons = []
sensors_and_beacons.each_slice(2) do |sensor, beacon|
dist = sensor.zip(beacon).sum { (_1 - _2).abs }
dy = (row - sensor[1]).abs
next if dy > dist
dx = dist - dy
x_min, x_max = [sensor[0]-dx, sensor[0]+dx].sort
no_beacons << (x_min..x_max)
end
# remove covered ranges
no_beacons = no_beacons.reject {|x| (no_beacons - [x]).any? { _1.cover?(x) }}
# merge ranges
no_beacons = no_beacons.inject([no_beacons.shift]) {|no_beacons, range|
next no_beacons if no_beacons.any? { _1.cover?(range) }
if overlap = no_beacons.find { _1.cover?(range.begin) }
range = (overlap.end + 1..range.end)
end
if overlap = no_beacons.find { _1.cover?(range.end) }
range = (range.begin..overlap.begin-1)
end
no_beacons << range
}
p no_beacons.sum(&:size) - sensors_and_beacons.to_a.select { _2 == row }.uniq.size
# part two
find_sab = ->(x, y) {
sensors_and_beacons.each_slice(2).find {|sensor, beacon|
dist = sensor.zip(beacon).sum { (_1 - _2).abs }
dist >= sensor.zip([x, y]).sum { (_1 - _2).abs }
}
}
max = 4_000_000
# max = 20
x = 0
y = 0
loop do
p y if (y % 10_000).zero?
sensor, _ = find_sab.(x, y)
dx = sensor[0] - x
if dx >= max / 2
dy = sensor[1] - y
y += dy.positive? ? 2 * dy + 1 : 1
end
loop do
sensor, beacon = find_sab.(x, y)
if sensor.nil?
p 4_000_000 * x + y
exit
end
dist = sensor.zip(beacon).sum { (_1 - _2).abs }
dy = (sensor[1] - y).abs
dx = (dist - dy).abs
x = sensor[0] + dx + 1
if x > max
x = 0
break
end
end
y += 1
break if y > max
end
Loading…
Cancel
Save