hauleth.dev
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2025/day07.livemd
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2025/day07.livemd
···
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end)
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```
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<!-- livebook:{"branch_parent_index":0} -->
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## Part 2
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```elixir
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|> Enum.sum_by(&elem(&1, 1))
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```
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<!-- livebook:{"branch_parent_index":0} -->
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## Image
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```elixir
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height = length([start | rest])
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width = byte_size(start)
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{height, width}
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```
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```elixir
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Image.new!(width, height)
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|> Image.mutate(fn img ->
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Image.Draw.point!(img, start_col, 0, color: :yellow)
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splitters
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|> Enum.with_index(1)
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|> Enum.reduce(MapSet.new([start_col]), fn {splits, y}, beams ->
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import MapSet, only: [intersection: 2, difference: 2, union: 2]
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for x <- beams do
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Image.Draw.point!(img, x, y, color: :green)
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end
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for x <- splits do
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Image.Draw.point!(img, x, y, color: :red)
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end
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hits = intersection(beams, splits)
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new_beams = for hit <- hits, dx <- [-1, 1], into: MapSet.new(), do: hit + dx
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beams = beams |> difference(hits) |> union(new_beams)
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beams
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end)
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#for {row, y} <- Enum.with_index(splitters, 1),
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# x <- row,
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# do: Image.Draw.point!(img, x, y, color: :red)
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img
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end)
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|> then(fn {:ok, img} -> img end)
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|> Image.resize!(5, interpolate: :nearest)
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```
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