20 lines
567 B
Elixir
20 lines
567 B
Elixir
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defmodule PascalsTriangle do
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@doc """
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Calculates the rows of a pascal triangle
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with the given height
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"""
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@spec rows(integer) :: [[integer]]
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def rows(num) do
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1..num
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|> Enum.reduce([[]], fn _, triangle -> [next(hd(triangle)) | triangle] end)
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|> Enum.take(num)
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|> Enum.reverse
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end
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defp next(from, acc \\ [])
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defp next([], _acc), do: [1]
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defp next([1], _acc), do: [1, 1]
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defp next([one, two | []], acc), do: [1 | Enum.reverse([1, one + two | acc])]
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defp next([one, two | rest], acc), do: next([two | rest], [one + two | acc])
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end
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