Hi everyone , I have a question which i faced a lot while implementing a problem and i usually handled it with segment tree but i think it must have an easier way
think that u have a set s
i want to find out number x position in this set
more formally i want s.find(x) — s.begin()
but c++ set can't handle this ! what should i do ? is there any way without using other structures to solve this ?
Auto comment: topic has been updated by _Ramtin_ (previous revision, new revision, compare).
http://stackoverflow.com/questions/13505562/getting-index-of-set-element-via-iterator
oh thanks man !
Be aware that
distancefunction wouldn't be constant-time while givenbidirectional iterators.If there are many such 'queries', then transform std::set into a vector. Vector supports upper_bound/lower_bound functions and by subtracting v.begin() you can get the index.
nope i needed an online sorted array for those problems and vector couldn't do that :)
Then you will have to write your own treap. I assume that distance works in linear time and is almost completely useless in your case.
There are ways to use g++ order statistic tree if you really need it.
read this http://codeforces.net/blog/entry/11080
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