34 lines
887 B
Elixir
34 lines
887 B
Elixir
defmodule Day8Part1 do
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def run do
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File.read!("input")
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|> input_to_instrs()
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|> run_until_loop()
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|> IO.puts()
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end
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def input_to_instrs(input) do
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input
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|> String.split("\n", trim: true)
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|> Enum.map(&String.split/1)
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|> Enum.with_index()
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|> Map.new(fn {[op, arg], idx} -> {idx, {op, String.to_integer(arg)}} end)
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end
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def run_until_loop(instrs), do: run_until_loop(instrs, 0, 0, MapSet.new())
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def run_until_loop(instrs, idx, acc, seen) do
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if MapSet.member?(seen, idx) do
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acc
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else
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seen = MapSet.put(seen, idx)
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{idx, acc} = execute(instrs[idx], idx, acc)
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run_until_loop(instrs, idx, acc, seen)
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end
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end
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def execute({"nop", _arg}, idx, acc), do: {idx + 1, acc}
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def execute({"jmp", arg}, idx, acc), do: {idx + arg, acc}
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def execute({"acc", arg}, idx, acc), do: {idx + 1, acc + arg}
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end
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Day8Part1.run()
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