I am having problem understanding how we are utilising Binary Indexed tree to solve the problem.The DFS part is clear as well as the notion of levels. But i am unable to understand how BIT is used. http://mirror.codeforces.com/contest/383/problem/C link.
Here is the editorial http://mirror.codeforces.com/blog/entry/10476
Sir i had already read the editorial and then i made the comment.Please provide any other valuable resources.
I would like to suggest you to read these resources for understanding BIT : http://zobayer.blogspot.in/2013/11/various-usage-of-bit.html http://community.topcoder.com/tc?module=Static&d1=tutorials&d2=binaryIndexedTrees http://mirror.codeforces.com/blog/entry/619
I do not have problem with BIT.It would be better if you could explain how it is used in this question