AOC Day One

aoc_day_1

# O(n)
def resulting_freq(collection, initial_value = 0)
  collection.inject(initial_value) do |final_value, line| 
    final_value += line.to_i 
  end
end

p resulting_freq([+1, +1, +1]) == 3
p resulting_freq([+1, +1, -2]) == 0
p resulting_freq([-1, -2, -3]) == -6

# collection = File.foreach('frequencies.txt')
# p resulting_freq(collection) == 518

def first_dup_freq(collection)
  cur = 0
  seen = { 0 => true }

  loop do
    collection.each do |line| 
      cur += line.to_i
      return cur if seen[cur]
      seen[cur] = true
    end
  end
  cur
end

p first_dup_freq([+1, -1]) == 0
p first_dup_freq([+3, +3, +4, -2, -4]) == 10
p first_dup_freq([-6, +3, +8, +5, -6]) == 5
p first_dup_freq([+7, +7, -2, -7, -4]) == 14

# collection = File.foreach('frequencies.txt')
# p first_dup_freq(collection) == 72889