100 lines
2.6 KiB
Elixir
100 lines
2.6 KiB
Elixir
defmodule Day2 do
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def part1(input) do
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input
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|> Enum.map(fn
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{opponent, "X"} -> {opponent, :rock}
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{opponent, "Y"} -> {opponent, :paper}
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{opponent, "Z"} -> {opponent, :scissors}
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end)
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|> Enum.map(&play/1)
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|> Enum.sum()
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end
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@rock 1
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@paper 2
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@scissors 3
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@lose 0
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@draw 3
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@win 6
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defp play({:rock, :rock}), do: @rock + @draw
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defp play({:paper, :rock}), do: @rock + @lose
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defp play({:scissors, :rock}), do: @rock + @win
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defp play({:rock, :paper}), do: @paper + @win
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defp play({:paper, :paper}), do: @paper + @draw
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defp play({:scissors, :paper}), do: @paper + @lose
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defp play({:rock, :scissors}), do: @scissors + @lose
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defp play({:paper, :scissors}), do: @scissors + @win
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defp play({:scissors, :scissors}), do: @scissors + @draw
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def part2(input) do
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input
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|> Enum.map(fn
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{opponent, "X"} -> {opponent, :lose}
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{opponent, "Y"} -> {opponent, :draw}
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{opponent, "Z"} -> {opponent, :win}
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end)
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|> Enum.map(&play2/1)
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|> Enum.sum()
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end
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defp play2({:rock, :win}), do: @win + @paper
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defp play2({:paper, :win}), do: @win + @scissors
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defp play2({:scissors, :win}), do: @win + @rock
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defp play2({:rock, :draw}), do: @draw + @rock
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defp play2({:paper, :draw}), do: @draw + @paper
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defp play2({:scissors, :draw}), do: @draw + @scissors
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defp play2({:rock, :lose}), do: @lose + @scissors
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defp play2({:paper, :lose}), do: @lose + @rock
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defp play2({:scissors, :lose}), do: @lose + @paper
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def input do
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with [input_filename] <- System.argv(),
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{:ok, input} <- File.read(input_filename) do
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input
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|> String.split([" ", "\n"], trim: true)
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|> Enum.map(fn
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"A" -> :rock
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"B" -> :paper
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"C" -> :scissors
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me -> me
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end)
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|> Enum.chunk_every(2)
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|> Enum.map(&List.to_tuple/1)
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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 day2.exs input_filename")
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end
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end
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Day2.run()
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