38 lines
1.0 KiB
Plaintext
38 lines
1.0 KiB
Plaintext
defmodule Digital do
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def mdroot(n), do: mdroot(n, 0)
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defp mdroot(n, persist) when n < 10, do: {n, persist}
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defp mdroot(n, persist), do: mdroot(product(n, 1), persist+1)
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defp product(0, prod), do: prod
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defp product(n, prod), do: product(div(n, 10), prod*rem(n, 10))
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def task1(data) do
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IO.puts "Number: MDR MP\n====== === =="
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Enum.each(data, fn n ->
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{mdr, persist} = mdroot(n)
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:io.format "~6w: ~w ~2w~n", [n, mdr, persist]
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end)
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end
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def task2(m \\ 5) do
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IO.puts "\nMDR: [n0..n#{m-1}]\n=== ========"
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map = add_map(0, m, Map.new)
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Enum.each(0..9, fn i ->
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first = map[i] |> Enum.reverse |> Enum.take(m)
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IO.puts " #{i}: #{inspect first}"
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end)
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end
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defp add_map(n, m, map) do
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{mdr, _persist} = mdroot(n)
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new_map = Map.update(map, mdr, [n], fn vals -> [n | vals] end)
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min_len = Map.values(new_map) |> Enum.map(&length(&1)) |> Enum.min
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if min_len < m, do: add_map(n+1, m, new_map),
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else: new_map
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end
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end
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Digital.task1([123321, 7739, 893, 899998])
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Digital.task2
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