Sciweavers

ICALP
2009
Springer

Towards Optimal Range Medians

14 years 11 months ago
Towards Optimal Range Medians
We consider the following problem: given an unsorted array of n elements, and a sequence of intervals in the array, compute the median in each of the subarrays defined by the intervals. We describe a simple algorithm which uses O(n) space and needs O(n log k + k log n) time to answer k such median queries. This improves previous algorithms by a logarithmic factor and matches a lower bound for k = O(n). Since, in contrast to previous approaches, the algorithm decomposes the range of element values rather than the array, it has natural generalizations to higher-dimensional problems ? it reduces a range median query to a logarithmic number of range counting queries.
Beat Gfeller, Peter Sanders
Added 03 Dec 2009
Updated 03 Dec 2009
Type Conference
Year 2009
Where ICALP
Authors Beat Gfeller, Peter Sanders
Comments (0)