37 lines
925 B
Ruby
37 lines
925 B
Ruby
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class Room
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attr_reader :name, :sector_id, :checksum
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def initialize(string)
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@name = string.split("-")[..-2].join("-")
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@sector_id = string.split("-")[-1].split("[")[0].to_i
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@checksum = string.split("[")[1][..-2]
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end
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def calculated_checksum
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letter_counts.sort_by { |k, v| [-v, -k] }.map(&:first)[0...5].join
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end
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def real?
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calculated_checksum == checksum
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end
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def letter_counts
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(name.chars - ["-"]).group_by(&:itself).to_h { |k, v| [k, v.count] }
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end
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def rotated_name
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1.upto(sector_id % 26).reduce(name) { |n, _| n.codepoints.map{ |c| ((((c + 1) - 97) % 26) + 97).chr }.join("") }
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end
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end
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input = STDIN.read.chomp
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room_lines = input.split("\n")
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rooms = room_lines.map { |line| Room.new line }
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part_1 = rooms.select(&:real?).sum(&:sector_id)
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puts "Part 1: #{part_1}"
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part_2 = rooms.find { |room| room.rotated_name.include? "northpole" }.sector_id
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puts "Part 2: #{part_2}"
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