AdventOfCode-2018/day1.cr

changes = File.read("day1_input").split("\n")
  .select { |it| !it.empty? } 
  .map(&.to_i)

puts "Final frequency: #{changes.sum}"

count = { 0 => 1 }
acc = 0

changes.cycle do |i|
  acc += i
  old_count = count[acc]? || 0
  new_count = old_count + 1
  count[acc] = new_count

  if new_count == 2
    puts acc
    exit
  end
end