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