Range mode and range median queries in constant time and sub-quadratic space |
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Authors: | Holger Petersen Szymon Grabowski |
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Affiliation: | a Universität Stuttgart, FMI, Universitätsstr. 38, D-70569 Stuttgart, Germany b Technical University of ?ód?, Computer Engineering Department, Al. Politechniki 11, 90-924 ?ód?, Poland |
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Abstract: | Given a list of n items and a function defined over sub-lists, we study the space required for computing the function for arbitrary sub-lists in constant time.For the function mode we improve the previously known space bound O(n2/logn) to O(n2loglogn/log2n) words.For median the space bound is improved to O(n2loglog2n/log2n) words from O(n2⋅log(k)n/logn), where k is an arbitrary constant and log(k) is the iterated logarithm. |
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Keywords: | Computational complexity Theory of computation Algorithms |
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