problems, results, top 5 on the left, parallel round results, top 5 on the right, analysis stream, analysis). Everything went pretty well for me in this round, I got the solution ideas quickly and only had to do heavy debugging once, in problem G. However, Um_nik chose a superior strategy and went for problem H in the end which gave him much more points, and won the round. Well done!
The hardest problem H was a pretty nice example of DP optimization. You have a tape that is infinite in both directions and is split into cells. You're going to write a given random permutation of size n<=15000 onto this tape in the following manner: you write the first number somewhere, then you either stay in the same cell or move one cell to the left or to the right, then write the second number there, then again either stay or move to an adjacent cell, write the third number there, and so on. Whenever you write a number into a cell that already has a number, the old number is overwritten and therefore discarded. After all n numbers have been written, we look at the resulting sequence written on the tape from left to right. What is the maximum possible size of an increasing subsequence of this sequence? Note that the given permutation is guaranteed to have been picked uniformly at random from all permutations of size n (which conveniently makes preparing the testcases for this problem so much easier!)
Thanks for reading, and check back next week!