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class Sensor
def initialize(sx, sy, bx, by)
@x = sx
@y = sy
@range = dist(bx, by)
end
attr_reader :x, :y, :range
def dist(x, y)
(@x - x).abs + (@y - y).abs
end
def cover?(x, y)
dist(x, y) <= @range
end
def edge
edges = []
at = [@x, @y - (@range + 1)]
until at[1] == @y
edges << at
at[0] += 1
at[1] += 1
end
until at[0] == @x
edges << at
at[0] -= 1
at[1] += 1
end
until at[1] == @y
edges << at
at[0] -= 1
at[1] -= 1
end
until at[0] == @x
edges << at
at[0] += 1
at[1] -= 1
end
edges
end
end
sensors = []
$stdin.readlines.each do |line|
c = line.scan(/x=(-?\d+), y=(-?\d+)/).flatten.map(&:to_i)
sensors << Sensor.new(*c)
end
max = 4_000_000
coord = sensors.map { |s|
s.edge.reject { |e|
e[0] < 0 || e[0] > max ||
e[1] < 0 || e[1] > max ||
sensors.any? { |s2| s2.cover?(*e) }
}
}.flatten(1).uniq[0]
puts coord[0] * 4_000_000 + coord[1]
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