#!/usr/bin/env ruby

require_relative '../common'

class Day03 < Day
  def self.priority(char)
    (("a".."z").to_a + ("A".."Z").to_a).index(char) + 1
  end

  def part1
    stdin.map(&:chars).map do |rucksack|
      self.class.priority((rucksack[0..(rucksack.size / 2) - 1] & rucksack[(rucksack.size / 2)..]).first)
    end.sum
  end

  def part2
    stdin.map(&:chars).each_slice(3).map do |group|
      self.class.priority group.inject { |res, g| res & g }.first
    end.sum
  end
end

Day03.run