127 lines
2.3 KiB
Ruby
127 lines
2.3 KiB
Ruby
# frozen_string_literal: true
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require 'set'
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require_relative 'intcode'
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Point = Struct.new(:x, :y) do
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def to_s
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"(#{x}, #{y})"
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end
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end
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class Hull
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def initialize
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@panels = Hash.new { |hash, key| hash[key] = :black }
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@painted = Set.new
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end
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def color_at(point)
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@panels[point]
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end
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def paint(point, color)
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@painted << point
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@panels[point] = color
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end
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def painted
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@painted.count
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end
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end
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class DoneExecuting < StandardError; end
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class Robot
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def initialize(program, hull)
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@computer = Intcode::Computer.new(program.as_memory) { on_input }
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@hull = hull
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@facing = :up
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@position = Point.new(0, 0)
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end
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def step
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color_output = nil
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direction_output = nil
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color_output = tick until color_output
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direction_output = tick until direction_output
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@hull.paint(@position, color(color_output))
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@facing = turn(@facing, direction_output)
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@position = move(@position, @facing)
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end
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def tick
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ret = @computer.tick
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raise DoneExecuting if ret == :done_executing
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ret
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end
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def on_input
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color = @hull.color_at(@position)
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case color
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when :black
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0
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when :white
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1
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else
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raise ArgumentError, "unexpected color: #{color}"
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end
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end
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def color(code)
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case code
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when 0
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:black
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when 1
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:white
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else
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raise ArgumentError, "unexpected color code: #{code}"
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end
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end
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DIRECTIONS = %i[up right down left].freeze
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def turn(facing, direction_code)
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idx = DIRECTIONS.index(facing)
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case direction_code
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when 0
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# left 90 degrees (ccw)
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next_idx = (idx - 1) % DIRECTIONS.length
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when 1
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# right 90 degrees (cw)
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next_idx = (idx + 1) % DIRECTIONS.length
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else
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raise ArgumentError, "unexpected direction code: #{direction_code}"
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end
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DIRECTIONS.fetch(next_idx)
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end
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def move(pos, direction)
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case direction
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when :up
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Point.new(pos.x, pos.y - 1)
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when :down
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Point.new(pos.x, pos.y + 1)
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when :left
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Point.new(pos.x - 1, pos.y)
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when :right
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Point.new(pos.x + 1, pos.y)
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else
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raise ArgumentError, "unexpected direction: #{direction}"
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end
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end
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end
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program = Intcode.read(File.join(__dir__, 'input'))
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hull = Hull.new
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robot = Robot.new(program, hull)
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loop do
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robot.step
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rescue DoneExecuting
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break
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end
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puts hull.painted
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