A method for routing of some embodiments defines global routes for nets in
an arbitrary region of a circuit layout in which each net has a set of
pins. The method uses a first set of lines of measure the length of the
global routes, a second set of lines to measure congestion of the global
routes, and a third set of lines to partition the arbitrary region into a
first set of sub-regions. For each net, the method identifies a global
route that connects a group of first-set sub-regions that contain the
net's set of pins.