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79 lines
1.8 KiB
79 lines
1.8 KiB
1 year ago
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require "strscan"
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include Math
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map, path = ARGF.read.chomp.split("\n\n")
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map = map.split("\n").each.with_index.with_object({}) {|(row,y),map|
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row.chars.each.with_index do |tile,x|
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map[[y,x]] = tile if tile != " "
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end
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}
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max_y = map.keys.map(&:first).max
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max_x = map.keys.map(&:last).max
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start_x = map.keys.select { _1.first.zero? }.map(&:last).min
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current = [0, start_x]
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facing = 0
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ss = StringScanner.new(path)
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until ss.eos?
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case
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when n = ss.scan(/\d+/)
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n = n.to_i
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n.times do
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y, x = current.zip([-sin(facing),cos(facing)]).map { _1 + _2 }.map(&:to_i)
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next_tile = map[[y,x]]
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unless next_tile
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puts
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p [y,x, facing]
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y, x = case facing
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when 0 then [y, 0]
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when PI/2 then [max_y, x]
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when PI then [y, max_x]
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when 3*PI/2 then [0, x]
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else fail "unexpected facing: #{facing}"
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end
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next_tile = map[[y,x]]
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while next_tile.nil?
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y, x = [y, x].zip([-sin(facing),cos(facing)]).map { _1 + _2 }.map(&:to_i)
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next_tile = map[[y,x]]
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end
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p [y,x,next_tile]
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end
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case next_tile
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when ?.
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current = [y,x]
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when ?#
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break
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else
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fail "unexpected tile: #{next_tile}"
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end
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end
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when dir = ss.scan(/R|L/)
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facing += case dir
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when ?R then -PI/2
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when ?L then PI/2
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else fail "unexpected dir: #{dir}"
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end
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facing %= 2*PI
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else
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fail ss.rest
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end
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end
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row, col = current.map { _1 + 1 }
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facing = case facing
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when 0 then 0
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when PI/2 then 3
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when PI then 2
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when 3*PI/2 then 2
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else
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fail "unexpected facing: #{facing}"
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end
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p [1000, 4, 1].zip([row, col, facing]).sum { _1 * _2 }
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