28 lines
827 B
Elixir
28 lines
827 B
Elixir
defmodule Part2 do
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def mark_seen(change, {prev_freq, seen}) do
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freq = prev_freq + change
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marked_freq = {freq, MapSet.member?(seen, freq)}
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acc = {freq, MapSet.put(seen, freq)}
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{[marked_freq], acc}
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end
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def run do
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File.stream!("input")
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|> Stream.map(&String.trim/1)
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# Trying to work out why can't cycle over the stream
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# Can't reproduce with this
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# Stream.cycle([1]) |> Stream.transform(0, fn one, prev -> {[prev + one], prev + one} end) |> Enum.find(fn x -> x == 25 end)
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# So maybe it's because a combination of the accumulator in the stream and Enum.find
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|> Stream.map(&String.to_integer/1)
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|> Stream.cycle()
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|> Stream.transform({0, MapSet.new([0])}, &mark_seen/2)
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|> Enum.find(fn {_freq, seen} -> seen end)
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|> elem(0)
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|> IO.puts()
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end
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end
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Part2.run()
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