KD tree search

Given a set of points (x,y) on a 2D coord system, identify list of 2D coords that are of distance less than x units long.
Eg.
Let x = 1;
Given (0,0), (0,1), (1, 2), (4,6);
Return 1 -> (0,0), (0,1)
Build the kd tree, use the range where the radius is unit long originated from anyone point to search on the kd tree, get a subset of points. Do the iteratively search on the subset…