By duckladydinh, history, 3 years ago, ,

Hello,

I am working on this problem on Kattis. I have been constantly thinking about it for the last 3 hours, but it seems that I am totally hopeless on this problem. Can someone give me some hints?

(I know 3 hours is too short :(. Normally I would only give up if it lasted for a few days, but I am in my urgent self-training period before an NWERC, so I change my plan to solve problems that I am totally hopeless instead of those that are hard but still somehow solvable and I use all this time just to make sure that it is really impossible for me)

Thank you. Happy Coding

• 0

 » 3 years ago, # | ← Rev. 2 →   +3 The answer is sum of the three sub-problems: No of inversions among known characters No of inversions among ? For each ?, no of inversions created against known characters To give you an example: 01?01? 0101: 1 inversion x 2^k -> 4 ?? -> 00, 01, 10, 11 -> 1 Number of inversions created by the first ? (consider both 0 and 1 cases) + Number of inversions created by the second ?.
•  » » 3 years ago, # ^ | ← Rev. 3 →   0 Thank you I have completed it and also understood it completely :)) You are a big help
•  » » » 3 years ago, # ^ |   -8 hi, I have some detailed question about problem. when k is a big number, will 2^k be overwhelming? how did you figure out the subproblem2? I used a math formula to do that. long case2 =0; for (int i=1; i
•  » » 3 years ago, # ^ |   0 I'm probably just doing something wrong but could you explain how this would work with ?0?
•  » » 5 weeks ago, # ^ |   0 Can you describe it in more easy way.I can't understand it. THANKS