Collision Test

Suppose we have m urns and we throw n balls at random into those urns, where m is much greater than n. Most of the balls will land in urns that were previously empty, but if a ball falls into an urn that already contains at least one ball then a collision has occurred. The collision test counts the number of collisions, and a generator passes this test if it doesn't induce too many or too few collisions. The function returns a uniform random no. in [0,1]. The test is failed if the value less than 0.001 or larger than 0.999