class Integer
  def valid_part_1_password?
    has_two_adjacent_digits? and digits_never_decrease?
  end

  def valid_part_2_password?
    has_exactly_two_adjacent_digits? and digits_never_decrease?
  end

  def digits_never_decrease?
    digits.reverse == digits.sort
  end

  def has_two_adjacent_digits?
    digits[..-2].zip(digits[1..]).any? { |x, y| x == y }
  end

  def has_exactly_two_adjacent_digits?
    threes = digits[..-3].zip(digits[1..-2]).zip(digits[2..]).map{ |x| x.flatten(1) }
    triple_indices = threes.each_with_index.select{ |trip, index| trip[0] == trip[1] && trip[0] == trip[2] }.map(&:last)
    pairs = digits[..-2].zip(digits[1..])
    pair_indices = pairs.each_with_index.select{ |pair, index| pair[0] == pair[1]}.map(&:last)
    pair_indices.any? { |pair_index| !triple_indices.include?(pair_index) && !triple_indices.include?(pair_index - 1) }
  end
end