What is the best thing you may possible do when having a eight hours train trip? Writing a blog post of course! That’s actually an interesting story by itself: Where I was and why it take that long to come back home! Anyway! Let’s say you’ve an array of integers, as usual from index 0 to […]

# datastructure

## Subsequences and Fenwick tree’s

Let’s say that we have a sequence A of 1<=n<=10^5 elements, and that this sequence may or may not be ordered but all the numbers {1…n} are present exactly once. And now given 1<=k<=10, you’re asked to find all the increasing sub-sequences of A with exactly k+1 elements. This is a problem I get from a competitive programming […]