52 lines
959 B
Markdown
52 lines
959 B
Markdown
# AOC 2024 Day 5
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## Section
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```elixir
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input = """
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"""
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```
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```elixir
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[rules, updates] = input |> String.split("\n\n")
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```
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```elixir
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rules = for rule <- rules |> String.split("\n"),
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[a, b] = rule |> String.split("|"),
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a = String.to_integer(a),
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b = String.to_integer(b),
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reduce: %{}
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do
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acc ->
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Map.update(acc, a, MapSet.new([b]), fn c -> MapSet.put(c, b) end)
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end
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```
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```elixir
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updates = for update <- updates |> String.trim() |> String.split("\n"),
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update = update |> String.trim() |> String.split(",") do
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for page <- update,
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page = String.to_integer(page) do
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page
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end
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end
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```
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```elixir
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rule_sorter = fn a, b ->
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!(Map.get(rules, b, MapSet.new()) |> MapSet.member?(a))
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end
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```
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```elixir
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for update <- updates,
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sorted = Enum.sort(update, rule_sorter),
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sorted != update,
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reduce: 0 do
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acc ->
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len = sorted |> Enum.count
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mid_idx = floor(len / 2)
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acc + Enum.at(sorted, mid_idx)
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end
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```
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