How the O(lg N) complexity in current problem ?

because you are filtering the list to new list means all elements are visited hence O(N),

next you use binary search to find index in O(lgN) time ,

so total complexity is O(N) + O(lgN) ~ O(N)

Hi @dragon

The algorithm doesn’t filter the given array into a new array. It just makes this decision using an `if`

condition. It’s also evident from the code that it neither creates an extra array nor does it execute an extra loop. Therefore, the time complexity is *O(log(N))*.