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input = ARGF.read
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def hash(label)
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label.chars.inject(0) {|n,c|
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(n + c.ord) * 17 % 256
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}
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end
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# part one
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p input.split(?,).sum { hash(_1) }
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# part two
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boxes = Hash.new {|h,k| h[k] = {} }
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input.scan(/(\w+)([-=])(\d+)?/).each do |label, op, focal_length|
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box = boxes[hash(label)]
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case op
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when ?-
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box.delete(label)
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when ?=
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box[label] = focal_length.to_i
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else
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fail
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end
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end
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p boxes.flat_map {|box_i, box|
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box.map.with_index {|(label, focal_length), lens_i|
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[1 + box_i, 1 + lens_i, focal_length].inject(:*)
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}
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}.sum
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