There is no O(logn) approach

#1

i complete 2 hour video for a problem but not get ,
most optimized solution that is O(logn).
why this approach is not have ?
please add this one also

#2

hey @Vipin_coder
this is part of competitive programming,
https://codeforces.com/blog/entry/14516
you can see this

#3

i completed 2 hours video , only for O(logn) solution, i already know all other solutions.