Finding Shadows among Disks
نویسندگان
چکیده
Given a set of n non-overlapping unit disks in the plane, a line ` is called blocked if it intersects at least one of the disks and a point p is called a shadow point if all lines containing p are blocked. In addition, a maximal closed set of shadow points is called a shadow region. We derive properties of shadow regions, and present an O(n) algorithm that outputs all shadow regions. We prove that the number of shadow regions is Ω(n) for some instances, which implies that the worst-case time complexity of the presented algorithm is optimal.
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