I couldn't find a discussion blog for this contest so here's one.

Does anyone know how to solve Ex?

How do you count the number of balanced binary search trees with N nodes? Balanced as in the left subtree size and the right subtree size differ by at most 1.

Thanks!

Round 649(Div 2) was rated for Yuki726 even though his rating was already above 2100? MikeMirzayanov is this some bug in the rating system?

How do I solve the interval scheduling problem but instead with k machines, meaning I can put the intervals in K different sets such that in each of the sets none of the intervals overlap and I want the maximum total interval, in O(nlogn) time or less.

Thanks!

Given a tree with n<=2e5 nodes how do you find the nodes that are on the diameter of the tree?

Thanks!

Given n<=1000000 and k<=n*(n-1)/2 construct a sequence of length n that has exactly k inversions. How do I solve this? Thanks!

Is there a discussion page? If not here is one.

Given a weighted undirected graph, you have multiple queries asking for the minimum possible maximum edge between two points. How do you solve this?

N<=100000 Q<=100000

Can someone provide an unofficial editorial for the Digit Sequence Problems? THANKS

Can someone please recommend a way to debug a code that passes the sample test cases but fails the main tests. Thanks

What will happen if you get hacked while your problem is locked, will is still be locked? I mean that is someone else hacks you will you get to change your solution?