Doubt in Persistent Segment trees

Revision en2, by bhargav104, 2017-01-17 11:37:37

Why do we always break down a query into prefix query when the problem involves Persistent Segment tree is it not possible to directly query a range [L,R]? For example consider this problem and the editorial — http://www.codechef.com/SNCKEL16/problems/SEGSUMQ

If we sort the vectors by the angle and then insert into the persistent segment tree in that order when we get a query <C,D> we can just query that segment tree in which all the vectors in it have lesser angle.

Am i missing something here? Could use some help. Thanks :)

Tags persistent segment tree, snackdown2016

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en3 English bhargav104 2017-01-17 11:38:11 0 (published)
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en1 English bhargav104 2017-01-17 11:36:59 568 Initial revision (published)