51 lines
1.2 KiB
Elixir
51 lines
1.2 KiB
Elixir
defmodule Day4 do
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def part1(input), do: mine(input, 1, "00000")
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def mine(input, nonce, prefix) do
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hash = :crypto.hash(:md5, input <> Integer.to_string(nonce)) |> Base.encode16()
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if String.starts_with?(hash, prefix), do: nonce, else: mine(input, nonce + 1, prefix)
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end
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def part2(input), do: mine(input, 1, "000000")
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def input do
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with [input] <- System.argv() do
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input
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else
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_ -> :error
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end
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end
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#######################
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# HERE BE BOILERPLATE #
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#######################
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def run do
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case input() do
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:error -> print_usage()
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input -> run_parts_with_timer(input)
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end
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end
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defp run_parts_with_timer(input) do
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run_with_timer(1, fn -> part1(input) end)
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run_with_timer(2, fn -> part2(input) end)
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end
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defp run_with_timer(part, fun) do
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{time, result} = :timer.tc(fun)
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IO.puts("Part #{part} (completed in #{format_time(time)}):\n")
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IO.puts("#{result}\n")
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end
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defp format_time(μsec) when μsec < 1_000, do: "#{μsec}μs"
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defp format_time(μsec) when μsec < 1_000_000, do: "#{μsec / 1000}ms"
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defp format_time(μsec), do: "#{μsec / 1_000_000}s"
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defp print_usage do
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IO.puts("Usage: elixir day4.exs input")
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end
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end
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Day4.run()
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