Terrain Guarding Problem(TGP), which is known to be NP-complete, asks to find a smallest set of guard locations on a terrain T such that every point on T is visible by a guard. Here, we study this problem on 1.5D orthogonal terrains where the edges are bound to be horizontal or vertical. We propose a 2-approximation algorithm that runs in O(n log m) time, where n and m are the sizes of input and output, respectively. This is an improvement over the previous best algorithm, which is a 2-approximation with O(n 2 ) running time.
Lyu andÜngör REF formulated a 2-approximation algorithm for the orthogonal terrain guarding problem that runs in O(nlogm), where m is the output size.
A Fast 2-Approximation Algorithm for Guarding Orthogonal Terrains
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Computer Science Mathematics