I calculate all possible combinations of sums and then check if there is at least one sum that matches the test input of a row. For performance reasons, it may be better to first create a list of all possible combinations of operators. Then you could iterate over this list, calculate the result, and stop early if a sum matches the test input.
I improved my performance of part 2 by using a mathematical approach, too.
def concat_nums(a, b) do
a * Integer.pow(10, Integer.digits(b) |> length) + b
end
Edit: Updated my solution and improved performance
My source code:
https://github.com/Flo0807/adventofcode/blob/main/2024/07.livemd
