foo6.cr

def max_index(enum : Enumerable(Int32)) : Int32?
  max = Int32::MIN
  index = nil
  
  enum.each_with_index do |el, idx|
    if el > max
      max = el
      index = idx
    end
  end

  index
end

def part1(banks = [] of Int32)
  seen = Set(Array(Int32)).new{ banks }
  cycles = (0..Int32::MAX).find do |cycles|
    break cycles if seen.includes? banks

    idx_bank = max_index(banks).not_nil!
    blocks = banks[idx_bank]
    banks[idx_bank] = 0

    blocks.downto(1) do |offset|
      banks[idx_bank - offset] += 1
    end

    seen << banks.dup
    nil
  end

  { cycles.not_nil!, banks, seen }
end