A problem suitable for BIT, the Binary Indexed Tree (Estimated Difficulty: above Senior, NOIP) "Sky Gate":http://www.luogu.org/problem/show?pid=1972#

More than two years ago, I thought it was an Ad Hoc problem and I had a try, but I failed. Now I've realized it is just a math problem with floyd! "Sky Gate":http://www.luogu.org/problem/show?pid=1037

An Ad Hoc problem? Maybe... It was two years ago that I know the problem for the first time, but I've just solved the problem RECENTLY! "Sky Gate":http://www.luogu.org/problem/show?pid=1033

An Ad Hoc problem? Maybe... It was five years ago that I know the problem for the first time, but I've just solved the problem RECENTLY! "Sky Gate":http://www.luogu.org/problem/show?pid=1058

A DP problem (Estimated Difficulty: Junior, NOIP) "Sky Gate":http://www.luogu.org/problem/show?pid=1156

Aug. 9th, 2015. My birthday today.~ I finally got 100 pts. in the "difficult" DP problem (I've already told you in advance that I am always a WEAK DISH!). "Sky Gate":http://www.luogu.org/problem/show?pid=1052