Advent of Code 2024 - Day 24

liamcmitchell · December 25, 2024, 8:55pm

I think that’s how I’ve solved it.

Part 1 example (2.8ms): 2024
Part 1 input (5.0ms): 56620966442854
Part 2 input (96.2ms): "chv,jpj,kgj,rts,vvw,z07,z12,z26"

I make graphs of logic and input wires only, no intermediate names. This lets you easily test if a node is logically equal. I look up the intermediate names from a map when needed.

github.com

liamcmitchell/advent-of-code/blob/4abc416e21ee88001295d4452b7a62fe25c90856/2024/24/1.exs#L112-L150


      
          def part(2, file) do
            map = file |> parse()
          
            map
            |> Map.keys()
            |> Enum.filter(fn wire -> wire |> String.starts_with?("z") end)
            |> Enum.sort()
            |> Enum.reduce({[], map}, fn wire, {swapped, map} ->
              bit = wire |> String.slice(1, 2) |> String.to_integer()
              expected = adder(bit)
              actual = resolve_tree(map, wire)
          
              if expected != actual do
                wires =
                  map
                  |> Map.keys()
                  |> Enum.map(fn wire -> {resolve_tree(map, wire), wire} end)
                  |> Map.new()
          
                case find_swap(wires, expected, actual) do

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