52 lines
1.2 KiB
Elixir
52 lines
1.2 KiB
Elixir
defmodule Day8 do
|
|
import Kernel, except: [node: 1]
|
|
|
|
def list, do: File.read!("input") |> String.split() |> Enum.map(&String.to_integer/1)
|
|
|
|
def node([child_count, data_count | rest]) do
|
|
{children, rest} = children(child_count, [], rest)
|
|
{data, rest} = Enum.split(rest, data_count)
|
|
{{data, children}, rest}
|
|
end
|
|
|
|
def children(0, acc, list), do: {Enum.reverse(acc), list}
|
|
|
|
def children(count, acc, list) do
|
|
{child, rest} = node(list)
|
|
children(count - 1, [child | acc], rest)
|
|
end
|
|
|
|
def sum_node({items, children}, sum) do
|
|
Enum.sum(items) + Enum.reduce(children, sum, &sum_node/2)
|
|
end
|
|
|
|
def part1 do
|
|
{tree, _} = node(list())
|
|
sum_node(tree, 0)
|
|
end
|
|
|
|
def select(nodes, indices) do
|
|
node_map =
|
|
nodes
|
|
|> Enum.with_index(1)
|
|
|> Map.new(fn {node, index} -> {index, node} end)
|
|
|
|
indices
|
|
|> Enum.map(&Map.get(node_map, &1))
|
|
|> Enum.reject(&(&1 === nil))
|
|
end
|
|
|
|
def value_node({items, []}), do: Enum.sum(items)
|
|
|
|
def value_node({items, children}) do
|
|
children |> select(items) |> Enum.map(&value_node/1) |> Enum.sum()
|
|
end
|
|
|
|
def part2 do
|
|
{tree, _} = node(list())
|
|
value_node(tree)
|
|
end
|
|
end
|
|
|
|
IO.puts(Day8.part1())
|
|
IO.puts(Day8.part2())
|