45 lines
762 B
Elixir
45 lines
762 B
Elixir
defmodule Day15 do
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defp read_input do
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Path.expand('input', Path.dirname(__ENV__.file))
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|> File.read!()
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end
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defp test_input do
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"""
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0,3,6
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"""
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end
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defp parse_numbers(text) do
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text
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|> String.trim()
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|> String.split(",")
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|> Enum.map(&String.to_integer/1)
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end
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defp next([previous | rest]) do
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{_, idx} =
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rest
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|> Enum.with_index()
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|> Enum.find({previous, -1}, fn {num, idx} -> num == previous end)
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idx + 1
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end
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defp run(log, limit) do
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if Enum.count(log) == limit do
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Enum.at(log, 0)
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else
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run([next(log) | log], limit)
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end
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end
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def part1 do
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read_input()
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|> parse_numbers()
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|> Enum.reverse()
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|> run(2020)
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end
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end
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Day15.part1() |> IO.inspect()
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