48 lines
1.0 KiB
Elixir
48 lines
1.0 KiB
Elixir
defmodule Day23Part1 do
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# @input "389125467"
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@input "137826495"
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def run do
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@input
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|> String.graphemes()
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|> Enum.map(&String.to_integer/1)
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|> play(100)
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|> cycle_to(1)
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|> Enum.drop(1)
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|> Enum.join()
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|> IO.puts()
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end
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def play(cups, 0), do: cups
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def play(cups, times), do: move(cups) |> play(times - 1)
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def move([current, a, b, c | rest]) do
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holding = [a, b, c]
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dest = find_dest(current, holding)
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insert(holding, dest, [current | rest])
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|> cycle_to(current, 1)
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end
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def find_dest(1, holding), do: find_dest(10, holding)
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def find_dest(current, holding) do
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dest = current - 1
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if dest in holding, do: find_dest(dest, holding), else: dest
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end
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def insert(holding, dest, circle) do
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[dest | rest] = cycle_to(circle, dest)
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[dest | holding] ++ rest
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end
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def cycle_to(circle, target, offset \\ 0) do
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circle
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|> Stream.cycle()
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|> Stream.drop_while(&(&1 != target))
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|> Stream.take(length(circle) + offset)
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|> Enum.drop(offset)
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end
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end
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Day23Part1.run()
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