Advent of Code 2024 - Day 24

bjorng · December 26, 2024, 10:22am

I managed to finally solve part 2 of the puzzle in Elixir, but not in a particular elegant way:

Inspired by Liam Mitchell’s elegant solution in the Elixir forum, I implemented this Erlang solution:

bjorng/advent-of-code/blob/main/2024/day24/day24.escript

#!/usr/bin/env escript

main(_) ->
    Input = get_input(),
    io:format("Part 1: ~p\n", [part1(Input)]),
    io:format("Part 2: ~p\n", [part2(Input)]).

part1({Inputs, Gates}) ->
    Map = maps:from_list(Inputs ++ Gates),
    ZWires = [Wire || {{z, _}=Wire, _} <- Gates],
    lists:sum([eval(Wire, Map) bsl Bit || {z,Bit}=Wire <- ZWires]).

eval({Op, [_,_]=Args}, Map) when is_atom(Op) ->
    [In1, In2] = [eval(Arg, Map) || Arg <- Args],
    case Op of
        'AND' -> In1 band In2;
        'OR' -> In1 bor In2;
        'XOR' -> In1 bxor In2
    end;
eval(Val, _Map) when is_integer(Val) ->

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