56 lines
1.1 KiB
Elixir
56 lines
1.1 KiB
Elixir
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defmodule Day4 do
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def part1 do
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158_126..624_574
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|> Enum.reduce(0, fn n, acc ->
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if test1(n) do
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IO.inspect(n)
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acc + 1
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else
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acc
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end
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end)
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end
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def part2 do
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158_126..624_574
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|> Enum.reduce(0, fn n, acc ->
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if test2(n) do
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IO.inspect(n)
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acc + 1
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else
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acc
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end
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end)
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end
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def test1(n) do
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cl = Integer.to_charlist(n)
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chunks = chunk_by_digits(cl)
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chunks == Enum.sort(chunks) && Enum.any?(chunks, &(length(&1) >= 2))
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end
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def test2(n) do
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cl = Integer.to_charlist(n)
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chunks = chunk_by_digits(cl)
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chunks == Enum.sort(chunks) && Enum.any?(chunks, &(length(&1) == 2))
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end
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def chunk_by_digits(cl, current_chunk \\ [], chunks \\ [])
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def chunk_by_digits([a, b | rest], current_chunk, chunks) do
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rest = [b | rest]
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if a == b do
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chunk_by_digits(rest, [a | current_chunk], chunks)
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else
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chunk_by_digits(rest, [], [Enum.reverse([a | current_chunk]) | chunks])
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end
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end
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def chunk_by_digits([a | []], current_chunk, chunks) do
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Enum.reverse([Enum.reverse([a | current_chunk]) | chunks])
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end
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end
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