The paper focuses on the Range-LIS problem and its generalizations, where the goal is to efficiently compute the longest increasing subsequence (LIS) within a given range of a sequence.
Key highlights:
1D-Range-LIS: The authors present a randomized algorithm that solves the 1D-Range-LIS problem in O(√n(m + n)(log n)^3 + k) time, where n is the length of the input sequence, m is the number of queries, and k is the cumulative length of the output subsequences. This breaks the quadratic barrier when m = Ω(√n).
2D-Range-LIS: The authors extend the 1D-Range-LIS problem to 2D, where the queries are axis-aligned rectangles in the 2D plane. They provide a randomized algorithm that solves the 2D-Range-LIS problem in O(√n(m + n)(log n)^5 + k) time.
Colored Variants: The authors also study the colored versions of the Range-LIS problem, where each element in the sequence is assigned a color. They provide efficient algorithms for the Colored-1D-Range-LIS and Colored-2D-Range-LIS problems.
Conditional Lower Bounds: The authors prove conditional lower bounds for the Colored-1D-Range-LIS problem, assuming the Combinatorial Boolean Matrix Multiplication Hypothesis, indicating that their algorithms might be near-optimal.
The authors combine several techniques, including dynamic programming, geometric data structures, random sampling, and classification of query ranges and colors, to achieve these results. The paper provides a comprehensive study of the Range-LIS problem and its variants, with potential applications in areas like time-series data analysis, social media usage trends, and genome sequence analysis.
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by Karthik C. S... lúc arxiv.org 04-09-2024
https://arxiv.org/pdf/2404.04795.pdfYêu cầu sâu hơn