Advent of Code 2021 - Day 18

bjorng · December 18, 2021, 7:06am

Here is my solution:

bjorng/advent-of-code-2021/blob/9a147ea3fb10fe6ae2eda8a567e06f11d779ab6f/day18/lib/day18.ex

defmodule Day18 do
  def part1(input) do
    parse(input)
    |> Enum.reduce(fn n, sum ->
      reduce([sum, n])
    end)
    |> magnitude
  end

  def part2(input) do
    numbers = parse(input)

    Enum.reduce(numbers, 0, fn n1, highest ->
      Enum.reduce(numbers -- [n1], highest, fn n2, highest ->
        max(highest, reduce([n1, n2]) |> magnitude)
      end)
    end)
  end

  @doc """

This file has been truncated. show original

UPDATE: I’ve also implemented a solution in Erlang with a different internal representation that simplifies the explode operation.