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30 lines
480 B
30 lines
480 B
6 years ago
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input = ARGF.read.chomp
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REGEX = Regexp.new(
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(?a..?z)
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.map {|x| [x, x.upcase] }
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.flat_map(&:permutation)
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.flat_map(&:to_a)
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.map(&:join)
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.join(?|)
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)
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def react(polymer)
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last = nil
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until polymer == last
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last = polymer
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polymer = polymer.gsub(REGEX, "")
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end
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polymer
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end
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# Part One
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# p react(input).size
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# Part Two
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p (?a..?z)
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.map {|unit| input.gsub(/#{unit}/i, "") }
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.map {|polymer| react(polymer) }
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.map {|reacted| reacted.size }
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.min
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