ใช้ 2SAT(2-Satisfiability) และ Optimize ด้วย SCC(StronglyConnectedComponent)
O(N+M)
- 2SAT https://www.youtube.com/watch?v=Ku-jJ0G4tIc
- 2SAT read https://cp-algorithms.com/graph/2SAT.html
- 2SAT codeforce https://codeforces.com/blog/entry/16205
- Tarjan SCC https://www.youtube.com/watch?v=wUgWX0nc4NY