32 lines
1.1 KiB
Elixir
32 lines
1.1 KiB
Elixir
defmodule AllYourBase do
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@doc """
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Given a number in input base, represented as a sequence of digits, converts it to output base,
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or returns an error tuple if either of the bases are less than 2
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"""
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@spec convert(list, integer, integer) :: {:ok, list} | {:error, String.t()}
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def convert(_digits, input_base, _output_base) when input_base < 2,
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do: {:error, "input base must be >= 2"}
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def convert(_digits, _input_base, output_base) when output_base < 2,
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do: {:error, "output base must be >= 2"}
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def convert([0 | digits], input_base, output_base), do: convert(digits, input_base, output_base)
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def convert(digits, input_base, output_base) do
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unless Enum.all?(digits, &valid_digit?(&1, input_base)) do
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{:error, "all digits must be >= 0 and < input base"}
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else
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result =
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digits
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|> Integer.undigits(input_base)
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|> Integer.digits(output_base)
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{:ok, result}
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end
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end
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defp valid_digit?(digit, base) when digit >= 0 and digit < base, do: true
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defp valid_digit?(_digit, _base), do: false
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end
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