arXivDaily arXiv每日学术速递 周一至周五更新
arXiv cs/0502032cs.DS
收藏

关于一维动态范围报告

On Dynamic Range Reporting in One Dimension

Christian Worm Mortensen, Rasmus Pagh, Mihai Patrascu

摘要:

我们考虑的问题,保持一个动态的整数集和回答查询的形式:报告一个点(相当于所有点)在一个给定的间隔。范围搜索是整数搜索的一种自然和基本变体,可以使用前导搜索来解决。然而,对于一个RAM的W位字,我们展示了如何执行更新在O(lg w)的时间和O(lglg w)的时间回答查询。更新时间与van Emde Boas结构相同,但查询时间以指数方式更快。现有的下限表明,实现我们的查询时间的前身搜索需要双指数较慢的更新。我们提出了一些论据来支持我们的解决方案是最佳的猜测。我们的解决方案是基于一个新的和有趣的递归的想法,这是“更极端”的范埃姆德博厄斯递归。van Emde Boas在trie中的每条路径上使用简单的递归(重复的减半),而我们在每条路径上使用非平凡的van Emde Boas式递归。尽管如此,我们的算法在从正确的角度看时非常干净。为了实现我们的数据结构的线性空间,我们解决了一个问题,这是独立的利益。我们开发了第一个需要次线性空间的动态完美散列方案。这给出了使用低空间的动态Bloomier滤波器(稀疏向量的近似存储方案)。我们加强以前的下界,以表明这些结果是最优的。

英文摘要:

We consider the problem of maintaining a dynamic set of integers and answering queries of the form: report a point (equivalently, all points) in a given interval. Range searching is a natural and fundamental variant of integer search, and can be solved using predecessor search. However, for a RAM with w-bit words, we show how to perform updates in O(lg w) time and answer queries in O(lglg w) time. The update time is identical to the van Emde Boas structure, but the query time is exponentially faster. Existing lower bounds show that achieving our query time for predecessor search requires doubly-exponentially slower updates. We present some arguments supporting the conjecture that our solution is optimal. Our solution is based on a new and interesting recursion idea which is "more extreme" that the van Emde Boas recursion. Whereas van Emde Boas uses a simple recursion (repeated halving) on each path in a trie, we use a nontrivial, van Emde Boas-like recursion on every such path. Despite this, our algorithm is quite clean when seen from the right angle. To achieve linear space for our data structure, we solve a problem which is of independent interest. We develop the first scheme for dynamic perfect hashing requiring sublinear space. This gives a dynamic Bloomier filter (an approximate storage scheme for sparse vectors) which uses low space. We strengthen previous lower bounds to show that these results are optimal.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑