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arXiv 0809.2097cs.DS
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约束最优区间的定位算法

Algorithms for Locating Constrained Optimal Intervals

Hsiao-Fei Liu, Peng-An Chen, Kun-Mao Chao

摘要:

在这项工作中,我们获得了以下新结果。1.给定一个数对序列$D=((h_1,s_1), (h_2,s_2) ..., (h_n,s_n))$,其中$s_i>0$为所有$i$,和一个数$L_h$,我们提出了一个O(n)-时间算法来寻找一个索引间隔$[i,j]$,最大化$\frac{\sum_{k=i}^{j} h_k}{\sum_{k=i}^{j} s_k}$受$\sum_{k=i}^{j} h_k \geq L_h$。2.给定一个数对序列$D=((h_1,s_1), (h_2,s_2) ..., (h_n,s_n))$,其中$s_i=1$为所有$i$,和一个整数$L_s$与$1\leq L_s\leq n$,我们提出了一个$O(n\frac{T(L_s^{1/2})}{L_s^{1/2}})$ -时间算法,用于找到一个索引间隔$[i,j]$,最大化$\frac{\sum_{k=i}^{j} h_k}{\sqrt{\sum_{k=i}^{j} s_k}}$受到$\sum_{k=i}^{j} s_k \geq L_s$,其中$T(n')$是所需的时间来解决所有对最短路径问题的$n'$节点的图。由Chan的最新结果\cite{Chan},$T(n')=O(n'^3 \frac{(\log\log n')^3}{(\log n')^2})$,我们的算法运行在次二次时间$O(nL_s\frac{(\log\log L_s)^3}{(\log L_s)^2})$ .

英文摘要:

In this work, we obtain the following new results. 1. Given a sequence $D=((h_1,s_1), (h_2,s_2) ..., (h_n,s_n))$ of number pairs, where $s_i>0$ for all $i$, and a number $L_h$, we propose an O(n)-time algorithm for finding an index interval $[i,j]$ that maximizes $\frac{\sum_{k=i}^{j} h_k}{\sum_{k=i}^{j} s_k}$ subject to $\sum_{k=i}^{j} h_k \geq L_h$. 2. Given a sequence $D=((h_1,s_1), (h_2,s_2) ..., (h_n,s_n))$ of number pairs, where $s_i=1$ for all $i$, and an integer $L_s$ with $1\leq L_s\leq n$, we propose an $O(n\frac{T(L_s^{1/2})}{L_s^{1/2}})$-time algorithm for finding an index interval $[i,j]$ that maximizes $\frac{\sum_{k=i}^{j} h_k}{\sqrt{\sum_{k=i}^{j} s_k}}$ subject to $\sum_{k=i}^{j} s_k \geq L_s$, where $T(n')$ is the time required to solve the all-pairs shortest paths problem on a graph of $n'$ nodes. By the latest result of Chan \cite{Chan}, $T(n')=O(n'^3 \frac{(\log\log n')^3}{(\log n')^2})$, so our algorithm runs in subquadratic time $O(nL_s\frac{(\log\log L_s)^3}{(\log L_s)^2})$.

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。

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