共查询到19条相似文献,搜索用时 94 毫秒
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B-树是一种平衡的多路查找树,在文件系统中有着很好的应用。该文分析了在B-树中删除一个关键词的几种情形,给出了B-树删除算法的具体实现,有助于对《数据结构》课程中B-树操作的更好理解。 相似文献
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唐自立 《计算机工程与应用》2007,43(5):45-48
Foster的删除HB(k)树的结点的算法的主要思想是先删除结点再自下而上处理某些子树,涉及自下而上的后退。提出一种新的删除HB(k)树的结点的算法,其主要思想是先自上而下处理某些子树再删除结点,不涉及自下而上的后退。举例说明新算法的执行过程。证明新算法是正确的。与Foster的删除HB(k)树的结点的算法相比,新算法不涉及辅助栈的使用。设n是HB(k)树的结点的个数。新算法的时间复杂性是O(log2n),与Foster的删除HB(k)树的结点的算法的相同。实验结果表明新算法的平均执行时间比Foster的删除HB(k)树的结点的算法短。新算法的空间复杂性是O(1),比Foster的删除HB(k)树的结点的算法低。 相似文献
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唐自立 《计算机工程与应用》2007,43(5)
Foster的删除HB(κ)树的结点的算法的主要思想是先删除结点再自下而上处理某些子树,涉及自下而上的后退.提出一种新的删除HB(κ)树的结点的算法,其主要思想是先自上而下处理某些子树再删除结点,不涉及自下而上的后退.举例说明新算法的执行过程.证明新算法是正确的.与Foster的删除HB(κ)树的结点的算法相比,新算法不涉及辅助栈的使用.设n是HB(κ)树的结点的个数.新算法的时间复杂性是0(log2n),与Foster的删除HB(κ)树的结点的算法的相同.实验结果表明新算法的平均执行对间比Foster的删除HB(κ)树的结点的算法短.新算法的空间复杂性是O(1),比Foster的删除HB(κ)树的结点的算法低. 相似文献
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一种新的删除AVL树的结点的算法 总被引:4,自引:1,他引:3
唐自立 《计算机应用与软件》2005,22(4):107-109
所有传统的删除AVL树的结点的算法的主要思想都是先删除结点再自下而上处理某些子树,涉及自下而上的后退。提出一种新的删除AVL树的结点的算法,其主要思想是先自上而下处理某些子树再删除结点,不涉及自下而上的后退。举例说明新算法的执行过程。证明新算法是正确的。与目前通常采用的Foster的算法相比,新算法不涉及辅助栈的使用。设n是AVL树的结点的个数。新算法的时间复杂性是O(log2n),与Foster的算法相同。实验结果表明新算法的平均执行时间比Foster的算法的短。新算法的空间复杂性是O(1),比Foster的算法的低。 相似文献
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DNA分子特性使得DNA计算具有极大的存储密度和高度的计算并行性。不管何种计算模型,DNA分子的选择和DNA编码都十分重要。提出了DNA计算中的B-树的数据结构设计方法。首先给出了B-树定义及其操作的形式化描述,接着介绍了本计算模型采用的3D结构DNA分子——k-arms分子结构,详细给出了一棵m阶B-树的构造步骤,最后实现了其查找、插入和删除等操作。提出了DNA分子计算的3D结构和分治策略,具有一定的可扩展性和并行性,对DNA计算的其他模型有参考价值。 相似文献
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为了提高IPv6的路由查找效率,针对IPv6路由前缀分布不均匀的问题,提出了一种基于B-树和Bloom filter相结合的IPv6路由查找算法(BTBF)。BTBF分为B-树和Bloom filter查找两部分,利用B-树查找路由前缀的前16 bit值,然后通过B-树节点中位向量的映射,将下一步链接到Bloom filter,再利用Bloom filter位数组的值映射提取下一跳。实验结果表明,BTBF算法与其他树型和Bloom filter类算法相比有效减少了空间和时间占用,在路由表项数变化较大的情况下也能维持稳定的查找性能。 相似文献
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A node in a 2-3-tree or B-tree is safe (with respect to insertion) if it has less than the maximally allowable number of keys. It is a deepest safe node if it is the deepest among all safe nodes on an access path. In this paper we analyze the probabilities for a random insertion to have its deepest safe node above the leaf level and the father-of-leaves level of its access path, using the well-known average case results of Yao (1978) for random 2-3- and B-trees. The implications of these results on various solutions proposed to support concurrent operations in 2-3-trees and B-trees are also discussed. 相似文献
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This paper presents an approach to enhancing B-tree indexing performance by using a replication technique called persistent caching. A notable feature of the approach is its compatibility with ordinary B-trees; it exploits only the otherwise unused area of each B-tree page, and the basic behavior of B-trees need not be changed. This paper evaluates the performance of persistently cached B-trees by showing the result of mathematical analysis and of experimental investigations. 相似文献
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本文给出两种构造三阶B树的算法,证明算法的时间复杂性,并给出用三阶B权实现热力公司的数据管理实例。 相似文献
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B-trees are useful for the maintenance of very large indexes. In this paper a deterministic model for the computation of space utilization and access path length in B-trees is presented. The considerations include a general form of B-trees that provides underflow and overflow treatment. Results for utilization and path length for some typical B-tree situations are given. 相似文献
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针对局域世界网络演化模型对于真实网络的描述过于简化的现象,提出局域世界删除演化网络模型。在网络的演化过程中既考虑了增加节点适应度对网络结构的影响,又对节点的删除和边的删除进行了探讨。研究表明增加节点的适应度可以使新节点加入时对已有网络节点的选择不只与已有网络节点的度有关;无论是删除节点还是删除边都会增加网络中度为1及度为2节点的比例,增加网络的平均路径长度,减小网络的聚类系数;随着局域世界的增大,kmax及网络的聚类系数都会增加。因此增大局域世界能够补偿删除所带来的影响。 相似文献
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This paper evaluates the use of standard database indexes and query processing as a way to do metric indexing in the LAESA approach. By utilizing B-trees and R-trees as pivot-based indexes, we may use well-known optimization techniques from the database field within metric indexing and search. The novelty of this paper is that we use a cost-based approach to dynamically evaluate which and how many pivots to use in the evaluation of each query. By a series of measurements using our database prototype we are able to evaluate the performance of this approach. Compared to using all available pivots for filtering, the optimized approach gives half the response times for main memory data, but much more varied results for disk resident data. However, by use of the cost model we are able to dynamically determine when to bypass the indexes and simply perform a sequential scan of the base data. The conclusion of this evaluation is that it is beneficial to create many pivots, but to use only the most selective ones during evaluation of each query. R-trees give better performance than B-trees when utilizing all pivots, but when being able to dynamically select the best pivots, B-trees often provide better performance. 相似文献
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《国际计算机数学杂志》2012,89(7):803-812
We present a Markov chain model for the analysis of the behaviour of binary search trees (BSTs) under the dynamic conditions of insertions and deletions. The model is based on a data structure called a lineage tree, which provides a compact representation of different BST structures while still retaining enough information to model the effect of insertions and deletions and to compute average path length and tree height. Different lineages in the lineage tree correspond to states in the Markov chain. Transition probabilities are based on the number of BST structures corresponding to each lineage. The model is based on a similar lineage tree model developed for B-trees. The BST model is not intended for practical computations, but rather as a demonstration of the generalizability of the lineage tree approach for modeling data structures such as B-trees, B*-trees, B+-trees, BSTs, etc. 相似文献
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Linda Pagli 《Information Systems》1979,4(3):227-234
A typical class of structures to organize ordered files is multiway trees, among which the most widely used is the perfectly balanced B-tree. In this paper we present the new family of BMT multiway trees, which are kept balanced in height, similarly to the classical binary height balanced trees used in central memory. The height of a BMT, that is the maximum search length for a key, is shown to be a logarithmic function of the number of keys in the worst case. Updating a BMT by key insertion is studied, and a technique to keep the tree balanced is presented. A comparison between the performance of BMTs and B-trees leads to the conclusion that the two structures are roughly comparable as to search length for a key, while BMTs require less memory space than B-trees for small node sizes. The real difference between BMTs and B-tree is in rebalancing operation, which requires a work proportional to the node size in the BMTs and to the tree height in the B-tree. 相似文献