an:07051770
Zbl 1421.68029
Hu, Xiaocheng; Sheng, Cheng; Tao, Yufei
Building an optimal point-location structure in \(O(\operatorname{sort}(n))\) I/Os
EN
Algorithmica 81, No. 5, 1921-1937 (2019).
00432384
2019
j
68P05 68U05
point location queries; bulkloading; external memory; computational geometry
Summary: We revisit the problem of constructing an external memory data structure on a planar subdivision formed by \(n\) segments to answer point location queries optimally in \(O(\log _B n)\) I/Os. The objective is to achieve the I/O cost of \(\operatorname{sort}(n) = O(\frac{n}{B} \log _{M/B} \frac{n}{B})\), where \(B\) is the number of words in a disk block, and \(M\) being the number of words in memory. The previous algorithms are able to achieve this either in expectation or under the tall cache assumption of \(M \ge B^2\). We present the first algorithm that solves the problem deterministically for all values of \(M\) and \(B\) satisfying \(M \ge 2B\).