Created
September 9, 2024 06:57
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| defmodule CeasarCipher do | |
| @lower Enum.to_list(?a..?z) | |
| @upper Enum.to_list(?A..?Z) | |
| defp map_within_range(c, range, shift) do | |
| if c in range do | |
| range | |
| |> Stream.cycle() | |
| |> Stream.drop(shift + (c - hd(range))) | |
| |> Stream.take(1) | |
| else | |
| [c] | |
| end | |
| end | |
| defp mapping(c, shift) when c in @lower, | |
| do: map_within_range(c, @lower, shift) | |
| defp mapping(c, shift) when c in @upper, | |
| do: map_within_range(c, @upper, shift) | |
| defp mapping(c, _shift), | |
| do: [c] | |
| def encode(string, shift) do | |
| string | |
| |> String.to_charlist() | |
| |> Stream.flat_map(&mapping(&1, shift)) | |
| |> Enum.to_list() | |
| |> to_string() | |
| end | |
| def decode(string, shift) do | |
| encode(string, length(@lower) - shift) | |
| end | |
| end | |
| string = "Hello World" | |
| target_shift = 10 | |
| string | |
| |> CeasarCipher.encode(target_shift) | |
| |> IO.inspect() | |
| |> CeasarCipher.decode(target_shift) | |
| |> IO.inspect() |
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