http://acm.timus.ru/problem.aspx?space=1&num=1513
It seems that those are the same problem.  In 1513,  just b=INF.
But that problem is of rating of 100, and Lemon Tale is of rating of around 500.

Yes,  Lemon Tale is just the same problem.  Even easier problem.

Problem rating lies heavily : 106 vs 400.

well it is true that this problem is harder in concept but that problem i think is just harder to implement in competition unless you use javabiginteger, but in c++ u must implement addition and diference with biginteger, and this problem is just done in about 10 lines of straight code

There exists four or five lines python solution using only python lists

1513 has tighter limits though
For this problem, you can implement a dp in O(n * (a + b)) but in Lemon Tale you can't

There are another similar problems, where rank lies. Say, 1285 is formally harder, then 1075. But if one have already solved 1075, then, probably, one may need to change just single dimensionality constant from 3 to 8 to get solution of 1285. Rate of ACs should be slightly less for harder, but latter problem, for sure.

Another factor is the optimistic one: people are getting smarter and smarter on an average. New problems are solved by less efforts. The technological singularity is coming!

Edited by author 18.01.2018 11:30