require "set"

class Santa
  attr_reader :visited_houses, :directions, :x, :y

  def initialize(directions, vh=Set.new)
    @directions = directions
    @visited_houses = vh
    @x = 0
    @y = 0
  end

  def self.for(string)
    new string.split("")
  end

  def handle_direction!(direction)
    case direction
    when "^"
      @y -= 1
    when "v"
      @y += 1
    when "<"
      @x -= 1
    when ">"
      @x += 1
    end
    @visited_houses.add [x, y]
  end

  def run!
    @visited_houses.add [x, y]

    directions.each do |direction|
      handle_direction! direction
    end
  end

  class Squad
    attr_reader :directions, :santas, :visited_houses
    def initialize(directions, count)
      @directions = directions
      @visited_houses = Set.new
      @santas = 1.upto(count).map { Santa.new nil, @visited_houses }
    end

    def self.for(string, count)
      new string.split(""), count
    end

    def run!
      directions.each_with_index do |direction, index|
        santas[index % 2].handle_direction! direction
      end
    end
  end
end