adevent of code problem 1.2

aoc_1.ex

defmodule Calibrate do
  def prob1(freqs), do: Enum.reduce(freqs, 0, &Kernel.+/2)

  def prob2(freqs), do: prob2(freqs, %{last: 0}, freqs)
  def prob2([], mem, freqs), do: prob2(freqs, mem, freqs)
  def prob2([h | t], %{last: last} = mem, freqs) do
    n = last + h
    case mem[n] do
      nil -> prob2(t, Map.merge(mem, %{:last => n, n => true}), freqs)
      true -> n
    end
  end
end

&Kernel.+/2

TIL 👍