84 lines
2.2 KiB
Elixir
84 lines
2.2 KiB
Elixir
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defmodule Day5 do
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def part1(input) do
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input
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|> Enum.reduce(_points = %{}, fn
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{{x, y1}, {x, y2}}, points ->
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for y <- y1..y2, reduce: points, do: (points -> plot(points, {x, y}))
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{{x1, y}, {x2, y}}, points ->
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for x <- x1..x2, reduce: points, do: (points -> plot(points, {x, y}))
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_point, points ->
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points
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end)
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|> Enum.count(fn {_point, count} -> count >= 2 end)
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end
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def part2(input) do
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input
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|> Enum.reduce(_points = %{}, fn
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{{x, y1}, {x, y2}}, points ->
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for y <- y1..y2, reduce: points, do: (points -> plot(points, {x, y}))
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{{x1, y}, {x2, y}}, points ->
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for x <- x1..x2, reduce: points, do: (points -> plot(points, {x, y}))
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{{x1, x1}, {x2, x2}}, points ->
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for x <- x1..x2, reduce: points, do: (points -> plot(points, {x, x}))
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{{x1, y1}, {x2, y2}}, points ->
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for point <- Enum.zip(x1..x2, y1..y2), reduce: points, do: (points -> plot(points, point))
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end)
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|> Enum.count(fn {_point, count} -> count >= 2 end)
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end
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defp plot(points, point) do
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Map.put(points, point, (points[point] || 0) + 1)
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end
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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(&String.to_integer/1)
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|> Enum.chunk_every(4)
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|> Enum.map(fn [x1, y1, x2, y2] -> {{x1, y1}, {x2, y2}} end)
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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 day5.exs input_filename")
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end
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end
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Day5.run()
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