Test if a curve is within another curve

I have a collection of closed curves. Some of these closed curves are contained within another curve. I simply want to sort my list of curves into 2 separate list.

1) Curves that are not contained within another curve

2) Curves that are contained within another curve

The reason why I want to do this is because I am offsetting all my curves to make a roof edge and I want the curves in the contained list to offset outwards, and the not contained curves to offset inwards. Right now I am sorting my curves manually, but that's cheating and I don't like cheating ;)