# Solved problems

Problems removed from the open catalog after a complete resolution.

- [Red-blue cut in digraphs](red-blue-cut.md): NP-complete, even for simple loopless digraphs with equal red and blue budgets.
- [Seating couples with fewest swaps](couples-seating-swaps.md): NP-complete and W[1]-hard parameterized by the number of unpaired people.