It is dynamic programming on the digits of a number. It involves problems like this one Codeforces problem 489C.
Also, this might be useful : http://stackoverflow.com/questions/22394257/how-to-count-integers-between-large-a-and-b-with-a-certain-property/22394258#22394258
My class 9 grades are very low. Do they make a big difference in the admission decision? What happened in your case?
According to the official IOI Syllabus, HLD and matrix operations are excluded. But I've seen a lot of -OI styled problems on these topics. Is it recommended to know them for IOI/IOITC?
Make a set with all co-ordinates of cultivated areas.
Then do a BFS/DFS and every time you encounter a new vertex, erase it from the set and add its number of empty neighbours to the current ans.
Keep doing BFSes till the set is empty.
Print the max of all such ans's found from BFSes
Can I get hints for this problem? My greedy solution gets 80 points on the grader though. I am unable to think of a DP solution for it.
