FPTAS for barrier covering problem with equal touching circles in 2D

In this paper, we consider a problem of optimal covering a barrier in the form of a line segment with equal circles distributed in a plane by moving their centers onto the segment or the line containing a segment. We require the neighboring circles in the cover to touch each other. The objective is to minimize the total traveled by circles Euclidian distance. The complexity status of the problem is not known. We propose an O(tAP(n)ε2)–time FPTAS for the problem, where n is the number of circles and t_AP(n) is the time complexity of solving an assignment problem which is at most O(n³).