51 lines
1.3 KiB
Elixir
51 lines
1.3 KiB
Elixir
defmodule Day14Part1 do
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use Bitwise
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def run do
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File.read!("input")
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|> String.split("\n", trim: true)
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|> Enum.map(&parse_command/1)
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|> Enum.reduce({nil, %{}}, &execute/2)
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|> sum_memory()
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|> IO.inspect()
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end
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def execute({:mask, mask}, {_mask, mem}), do: {mask, mem}
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def execute({:mem, addr, value}, {mask, mem}) do
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masked_value = apply_mask(value, mask)
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{mask, Map.put(mem, addr, masked_value)}
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end
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def sum_memory({_mask, mem}), do: Map.values(mem) |> Enum.sum()
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def apply_mask(value, {andmask, ormask}), do: (value &&& andmask) ||| ormask
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def parse_command("mask = " <> mask), do: {:mask, decode_mask(mask)}
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def parse_command(mem_command) do
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[addr, value] =
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mem_command
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|> String.split(["mem[", "] = "], trim: true)
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|> Enum.map(&String.to_integer/1)
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{:mem, addr, value}
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end
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def decode_mask(mask) when byte_size(mask) == 36 do
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<<andmask::36>> = for <<bit::binary-1 <- mask>>, into: <<>>, do: andmask_bit(bit)
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<<ormask::36>> = for <<bit::binary-1 <- mask>>, into: <<>>, do: ormask_bit(bit)
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{andmask, ormask}
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end
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def andmask_bit("X"), do: <<1::1>>
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def andmask_bit("1"), do: <<1::1>>
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def andmask_bit("0"), do: <<0::1>>
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def ormask_bit("X"), do: <<0::1>>
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def ormask_bit("1"), do: <<1::1>>
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def ormask_bit("0"), do: <<0::1>>
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end
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Day14Part1.run()
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