flerda/sumset — comment on commit d2245920f98518520cb60fe7ad3682645017fe1d
File: SumSet/Main.cs line 42
By flerda:

This is similar to what I had in mind.
See a4891895918abee3f99d482fa0e9bfc19cde2f67 for an implementation of what I had in mind.

This works fine, and in fact is probably slightly faster.
The only drawback is that it has a side-effect: it modifies one of its inputs, namely listOfSets.
This is frowned upon by some, because it makes your code harder to understand unless it very uber-clear what is going on.