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75 lines
1.4 KiB
75 lines
1.4 KiB
3 years ago
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require "strscan"
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input = ARGF.read.split("\n")
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class IllegalCharacter < StandardError
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attr_reader :char
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def initialize(char)
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@char = char
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end
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end
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def parse(line)
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ss = StringScanner.new(line)
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stack = []
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until ss.eos?
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case
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when ss.scan(/\(/)
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stack << ?(
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when ss.scan(/\[/)
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stack << ?[
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when ss.scan(/\{/)
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stack << ?{
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when ss.scan(/</)
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stack << ?<
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when ss.scan(/\)/)
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raise IllegalCharacter.new(?)) unless stack.pop == ?(
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when ss.scan(/\]/)
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raise IllegalCharacter.new(?]) unless stack.pop == ?[
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when ss.scan(/\}/)
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raise IllegalCharacter.new(?}) unless stack.pop == ?{
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when ss.scan(/>/)
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raise IllegalCharacter.new(?>) unless stack.pop == ?<
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else
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fail
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end
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end
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stack
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end
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# points = {
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# ?) => 3,
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# ?] => 57,
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# ?} => 1197,
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# ?> => 25137,
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# }
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# p input.sum {|line|
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# begin
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# parse(line)
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# 0
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# rescue IllegalCharacter => e
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# points.fetch(e.char)
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# end
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# }
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POINTS = ")]}>".chars.map.with_index.to_h.transform_values { _1 + 1 }
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def score(closing)
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total = 0
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closing.each do |char|
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total *= 5
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total += POINTS.fetch(char)
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end
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total
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end
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complements = "() [] {} <>".split(" ").map(&:chars).to_h
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scores = input
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.map { parse(_1) rescue [] }
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.reject(&:empty?)
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.map {|remaining| remaining.reverse.map { complements.fetch(_1) }}
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.map { score(_1) }
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p scores.sort.fetch(scores.length / 2)
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