Given obstacles and crossing areas together with two pairs of terminals on
the plane, our algorithm finds a pair of rectilinear paths which connect th
e pairs of terminals, neither pass through any obstacle nor cross each othe
r except in the crossing areas, and minimize the total length, where all ob
stacles and crossing areas are assumed to be axis-parallel rectangles. The
algorithm takes O(n log n) time and O(n) space, where n is the total number
of obstacles and crossing areas.