A Linear-Time Approximation Algorithm for the Orthogonal Terrain Guarding Problem

Wei-Yu Lai; Tien-Ruey Hsiang

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arXiv · 1804.11088

A Linear-Time Approximation Algorithm for the Orthogonal Terrain Guarding Problem

Wei-Yu Lai·Tien-Ruey Hsiang

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Abstract

In this paper, we consider the 1.5-dimensional orthogonal terrain guarding problem. In this problem, we assign an x-monotone chain T because each edge is either horizontal or vertical, and determine the minimal number of vertex guards for all vertices of T. A vertex vi sees a point p on T if the line segment connecting vi to p is on or above T. We provide an optimal algorithm with O(n) for a subproblem of the orthogonal terrain guarding problem. In this subproblem, we determine the minimal number of vertex guards for all right(left) convex verteices of T. Finally, we provide a 2-approximation algorithm that solves the 1.5-dimensional orthogonal terrain guarding problem in O(n).

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BibTeX RIS

Wei-Yu Lai, Tien-Ruey Hsiang. 2018-04-30. A Linear-Time Approximation Algorithm for the Orthogonal Terrain Guarding Problem. https://arxiv.org/abs/1804.11088

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