41 lines
1.1 KiB
Elixir
41 lines
1.1 KiB
Elixir
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defmodule Two do
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def bool_int(true), do: 1
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def bool_int(false), do: 0
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def part1(id_list) do
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id_list
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|> Stream.map(fn id ->
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id
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|> String.codepoints()
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|> Enum.reduce(%{}, fn l, acc -> Map.update(acc, l, 1, &(&1 + 1)) end)
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|> Map.values()
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|> MapSet.new()
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end)
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|> Enum.to_list()
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|> Enum.reduce([0, 0], fn s, [x, y] ->
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[x + bool_int(2 in s), y + bool_int(3 in s)]
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end)
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|> Enum.reduce(1, fn i, a -> a * i end)
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end
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def part2(id_list) do
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id_list
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|> Stream.map(&String.trim_trailing/1)
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|> Enum.to_list()
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|> permute_all_pairs()
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|> List.flatten()
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|> Enum.reduce_while("", fn {id1, id2}, _ ->
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case String.myers_difference(id1, id2) do
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[eq: p1, del: <<_x::size(8)>>, ins: <<_y::size(8)>>, eq: p2] -> {:halt, p1 <> p2}
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_ -> {:cont, ""}
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end
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end)
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end
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def permute_all_pairs([]), do: []
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def permute_all_pairs(list), do: [permute_pairs(list) | permute_all_pairs(tl(list))]
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def permute_pairs([]), do: []
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def permute_pairs([cur | rest]), do: Enum.map(rest, &{cur, &1})
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end
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