Advent of code 2020 Day 15

aoc_2020_day_15.rb

@input = [0,12,6,13,20,1,17]
@numbers = {}

@input.each_with_index do |input, index|
  @numbers[input] = { count: 1, last_spoken_on: index + 1, last_spoken_before_on: nil }
end

@last_number_spoken = @input.last
@turn_count = @input.length + 1

while(@turn_count <= 30000000) do
  if @numbers[@last_number_spoken][:count] == 1
    @spoken_number = 0
  elsif @numbers[@last_number_spoken][:count] > 1
    @spoken_number = @numbers[@last_number_spoken][:last_spoken_on] - @numbers[@spoken_number][:last_spoken_before_on]
  else
    @spoken_number = 0
  end

  @numbers[@spoken_number] ||= {count: 0, last_spoken_on: nil, last_spoken_before_on: nil}
  @numbers[@spoken_number][:last_spoken_before_on] = @numbers[@spoken_number][:last_spoken_on]
  @numbers[@spoken_number][:last_spoken_on] = @turn_count
  @numbers[@spoken_number][:count] += 1

  @last_number_spoken = @spoken_number
  @turn_count += 1
end

puts @spoken_number.inspect