For Problem B, would the maximum $$$a_{i}$$$|$$$a_{j}$$$ = 2n-1 -> so f(n-1 , n) = n^2-n-k-2nk?

How would you solve f(i,n) > f(n-1,n) in that case?

Problem: 1554B - Cobb
Editorial : https://codeforces.net/blog/entry/93321