24 lines
583 B
Ruby
24 lines
583 B
Ruby
# frozen_string_literal: true
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input = '' # TODO
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range = Range.new(*input.split('-').map(&:to_i))
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def pairwise(arr)
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arr[0...-1].zip(arr[1..])
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end
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count = range.count do |n|
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# 1. All numbers in this range are six digits
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# 2. All numbers in this range are in this range
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digits = n.digits.reverse
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# 3. Two adjacent digits are the same
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double = pairwise(digits).any? { |pair| pair.first == pair.last }
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# 4. Going from left to right, the digits *never decrease*
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monotonic = pairwise(digits).none? { |pair| pair.last < pair.first }
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double && monotonic
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end
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pp count
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