n080w820-4-0-9-1-9-6-2 Solved！

It took us 23 days machine running to solve the problem by single threading.　The challenge lies in proving that it is optimal as well as discovering UB.

 n080w820-4-0-9-1-9-6-2: LB=4305 UB=4305

This instance was the hardest problem in INRC2, we believe. Since the solving time is not practical, we will make to reduce the solving time less than 8 hours using our improved CuPDLP with a low-cost GPU and multi-threading CPU. It will be the real challenge. 

There is now only one remaining unresolved instance for INRC2 on our side! 

n080w820-4-0-9-1-9-6-2