97 lines
2.2 KiB
Elixir
97 lines
2.2 KiB
Elixir
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defmodule Aoc.Solution.Day06 do
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@name "Day 6: Probably a Fire Hazard"
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@behaviour Solution
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@impl Solution
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def get_name, do: @name
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@impl Solution
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def parse!(raw) do
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r = ~r/ ?(\S+) (\d+),(\d+) through (\d+),(\d+)/
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raw
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|> String.split("\n")
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|> Enum.map(fn row ->
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[_, verb, x1, y1, x2, y2] = Regex.run(r, row)
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{verb, String.to_integer(x1)..String.to_integer(x2), String.to_integer(y1)..String.to_integer(y2)}
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end)
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end
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@impl Solution
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def solve_first_part(input) do
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lit = MapSet.new()
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change_state(lit, input) |> MapSet.size()
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end
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@impl Solution
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def solve_second_part(input) do
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lit = Map.new()
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adjust_brightness(lit, input)
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end
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defp change_state(lit, []) do
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lit
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end
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defp change_state(lit, [ {verb, xset, yset} | remaining]) do
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change = for x <- xset do
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for y <- yset do
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{x, y}
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end
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end |> List.flatten() |> MapSet.new()
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case verb do
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"on" ->
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change_state(MapSet.union(lit, change), remaining)
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"off" ->
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change_state(MapSet.difference(lit, change), remaining)
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"toggle" ->
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to_lit = MapSet.difference(change, lit)
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to_unlit = MapSet.difference(lit, change)
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change_state(MapSet.union(to_lit, to_unlit), remaining)
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end
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end
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defp adjust_brightness(lit, []) do
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Map.values(lit) |> Enum.sum
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end
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defp adjust_brightness(lit, [ {verb, xset, yset} | remaining]) do
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change = for x <- xset do
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for y <- yset do
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{x, y}
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end
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end |> List.flatten()
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updated = case verb do
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"on" ->
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Enum.reduce(change, lit, fn xy, acc ->
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if Map.has_key?(acc, xy) do
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%{acc | xy => Map.get(acc, xy) + 1}
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else
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Map.put(acc, xy, 1)
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end
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end)
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"off" ->
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Enum.reduce(change, lit, fn xy, acc ->
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if Map.has_key?(acc, xy) do
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%{acc | xy => max(Map.get(acc, xy) - 1, 0)}
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else
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acc
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end
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end)
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"toggle" ->
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Enum.reduce(change, lit, fn xy, acc ->
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if Map.has_key?(acc, xy) do
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%{acc | xy => Map.get(acc, xy) + 2}
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else
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Map.put(acc, xy, 2)
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end
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end)
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end
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adjust_brightness(updated, remaining)
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end
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end
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