this is the part where the challenges start to get hard. implementing
the naive solution for part 1 did not take much time. used a hashset
since it's easier than using arrays, but slightly less performant. I
expected the naive solution would not work for part 2 due to the size of
the problem but it still worked, although it did take a few seconds to
finish. the solution i would have used if part 2 took too long would be
to trace some 45* rays from the end points of horizontal beams and
subtract the area inside from the largest sand triangle.
