Abstract
We consider range queries that search for low-frequency elements (least frequent elements and α-minorities) in arrays. An α-minority of a query range has multiplicity no greater than an α fraction of the elements in the range. Our data structure for the least frequent element range query problem requires O(n) space, O(n3/2) preprocessing time, and O(n) query time. A reduction from boolean matrix multiplication to this problem shows the hardness of simultaneous improvements in both preprocessing time and query time. Our data structure for the α-minority range query problem requires O(n) space, supports queries in O(1/α) time, and allows α to be specified at query time.
Original language | English (US) |
---|---|
Pages (from-to) | 901-913 |
Number of pages | 13 |
Journal | Algorithmica |
Volume | 72 |
Issue number | 4 |
DOIs | |
State | Published - Aug 19 2015 |
Externally published | Yes |
Keywords
- Data structures
- Least frequent element
- Minority
- Range queries
ASJC Scopus subject areas
- General Computer Science
- Computer Science Applications
- Applied Mathematics