Advent of Code, day 14

day14.rb

class Raindeer

  attr_reader :name

  def initialize(name:, speed:, sprint_time:, rest_time:)
    @name = name  
    @speed = speed
    @sprint_time = sprint_time
    @rest_time = rest_time
  end

  def distance_after(time)
    cycle_number, seconds_into_cycle = time.divmod(cycle_time)
    distance_for_full_cycles = cycle_number * distance_per_full_cycle
    flight_time_for_current_cycle = [seconds_into_cycle, @sprint_time].min
    distance_for_current_cycle = flight_time_for_current_cycle * @speed
    distance_for_full_cycles + distance_for_current_cycle
  end

  private

  def cycle_time
    @sprint_time + @rest_time
  end

  def distance_per_full_cycle
    @sprint_time * @speed
  end
   
end

def parse(file)
  file.each_line.map do |line|
    raise unless line =~ /^(\w+)\D+(\d+)\D+(\d+)\D+(\d+)/
    Raindeer.new(
      name: $1,
      speed: Integer($2),
      sprint_time: Integer($3),
      rest_time: Integer($4),
    )
  end
end

def best_distance_after(time)
  @raindeers.map do |raindeer|   
    raindeer.distance_after(time)
  end.max
end

RACE_TIME = 2503
@raindeers = File.open("input", "r") { |file| parse(file) }

# part 1
puts best_distance_after(RACE_TIME)

# part 2   
scores = {}
(1..RACE_TIME).each do |time|
  best_distance = best_distance_after(time)
  @raindeers.each do |raindeer|
    if raindeer.distance_after(time) == best_distance
      scores[raindeer.name] ||= 0
      scores[raindeer.name] += 1
    end
  end
end
puts scores.values.max