83 lines
1.7 KiB
Elixir
83 lines
1.7 KiB
Elixir
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defmodule AOC.Day7 do
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use AOC.Day, day: 7
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def parse_input(lines) do
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Enum.map(lines, fn
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"$ cd " <> arg ->
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{:cd, arg}
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"$ ls" ->
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:ls
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"dir " <> arg ->
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{:dir, arg}
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line ->
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[size, file] = String.split(line)
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{:file, String.to_integer(size), file}
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end)
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end
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def part1(input) do
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input
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|> get_file_sizes()
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|> get_directory_sizes()
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|> Enum.map(fn {_, size} -> size end)
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|> Enum.filter(&(&1 <= 100_000))
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|> Enum.sum()
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end
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def part2(input) do
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file_sizes = get_file_sizes(input)
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total_size =
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file_sizes
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|> Enum.map(&elem(&1, 1))
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|> Enum.sum()
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size_needed = total_size - 40_000_000
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file_sizes
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|> get_directory_sizes()
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|> Enum.map(&elem(&1, 1))
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|> Enum.filter(fn size -> size >= size_needed end)
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|> Enum.min()
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end
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def get_file_sizes(input) do
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Enum.reduce(input, {[], []}, fn
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{:cd, "/"}, {_, sizes} ->
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{["/"], sizes}
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{:cd, ".."}, {[_ | path], sizes} ->
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{path, sizes}
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{:cd, dir}, {path, sizes} ->
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{[dir | path], sizes}
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{:file, size, file}, {path, sizes} ->
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{path, [{[file | path], size} | sizes]}
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_, acc ->
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acc
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end)
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|> elem(1)
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end
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def get_directory_sizes(file_sizes) do
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file_sizes
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|> Enum.reduce(%{}, fn {[_ | path], size}, acc ->
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path = Enum.reverse(path)
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update_directory_size(acc, size, path)
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end)
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end
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def update_directory_size(sizes, file_size, file_path) do
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Enum.reduce(file_path, {sizes, []}, fn dir, {sizes, cur_path} ->
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cur_path = [dir | cur_path]
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{Map.update(sizes, cur_path, file_size, &(&1 + file_size)), cur_path}
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end)
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|> elem(0)
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end
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end
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