the closest-pair problem can be posted in the 3-dimensional space, in which the euclidean distance between two points p1(x1, y1, z1) and p2(x2, y2, z2) is defined as d = √(x1−x2)^2+(y1−y2)^2+(z1−z2)^2...

the closest-pair problem can be posted in the 3-dimensional space, in which the euclidean distance between two points p1(x1, y1, z1) and p2(x2, y2, z2) is defined as d = √(x1−x2)^2+(y1−y2)^2+(z1−z2)^2 what is the time-efficiency class of the brute-force algorithm for the 3-dimensional closest-pair problem?