27 lines
811 B
Elixir
27 lines
811 B
Elixir
defmodule MoveToFront do
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@table Enum.to_list(?a..?z)
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def encode(text), do: encode(to_char_list(text), @table, [])
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defp encode([], _, output), do: Enum.reverse(output)
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defp encode([h|t], table, output) do
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i = Enum.find_index(table, &(&1 == h))
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encode(t, move2front(table, i), [i | output])
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end
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def decode(indices), do: decode(indices, @table, [])
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defp decode([], _, output), do: Enum.reverse(output) |> to_string
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defp decode([h|t], table, output) do
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decode(t, move2front(table, h), [Enum.at(table, h) | output])
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end
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def move2front(table, i), do: [Enum.at(table,i) | List.delete_at(table, i)]
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end
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Enum.each(["broood", "bananaaa", "hiphophiphop"], fn word ->
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IO.inspect word
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IO.inspect enc = MoveToFront.encode(word)
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IO.puts "#{word == MoveToFront.decode(enc)}\n"
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end)
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