I was going through a blog (https://cp-algorithms.com/data_structures/segment_tree.html )

It says something like -

The query function is also almost equivalent, only now the lower_bound function of the multiset function should be called instead (std::lower_bound only works in O(logn) time if used with random-access iterators).

I need some help, to clarify few doubts(might help others too) —

• How can I define multiset with random-access iterators in C++?
• Can we find the rank of an element using it?
• How is it different from "C++ STL: Policy based data structures"?