My simple solution with reduce and pattern matching:
defmodule AdventOfCode.Day02 do
def part1(input) do
{hor, dep} = input |> parse_input() |> Enum.reduce({0, 0}, &move/2)
hor * dep
end
def part2(input) do
{hor, dep, _aim} = input |> parse_input() |> Enum.reduce({0, 0, 0}, &move_2/2)
hor * dep
end
def move({:up, x}, {hor, dep}), do: {hor, dep - x}
def move({:down, x}, {hor, dep}), do: {hor, dep + x}
def move({:forward, x}, {hor, dep}), do: {hor + x, dep}
def move_2({:down, x}, {hor, dep, aim}), do: {hor, dep, aim + x}
def move_2({:up, x}, {hor, dep, aim}), do: {hor, dep, aim - x}
def move_2({:forward, x}, {hor, dep, aim}), do: {hor + x, dep + aim * x, aim}
def parse_input(input) do
input
|> String.split("\n", trim: true)
|> Enum.map(&String.split/1)
|> Enum.map(fn [d, x] -> {String.to_atom(d), String.to_integer(x)} end)
end
end
It’s time for Livebook again
