43 lines
806 B
Elixir
43 lines
806 B
Elixir
defmodule Primes do
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defp sieve([], acc, _) do
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Enum.reverse(acc)
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end
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defp sieve([h | t], acc, n) do
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if h * h > n do
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Enum.reverse(acc) ++ [h | t]
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else
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sieve(
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Enum.filter(t, fn x -> rem(x, h) != 0 end),
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[h | acc],
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n)
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end
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end
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def primes(n) do
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l = Enum.to_list(2..n)
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sieve(l, [], n)
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end
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defp largest_permutation_set(p) do
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p |> Enum.group_by(fn x -> x
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|> Integer.to_string()
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|> String.to_charlist()
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|> Enum.sort() end)
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|> Map.values()
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|> Enum.max_by(&length/1)
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end
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def run(n, d) do
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p = primes(n)
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p = Enum.filter(p, fn x ->
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String.length(Integer.to_string(x)) >= d
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end)
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IO.puts(length(p))
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IO.puts(length(largest_permutation_set(p)))
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end
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end
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Primes.run(1_000_000, 6);
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