Ah, but remember this post:
#3 was changed to 250 million 200 character strings, apparently the point was that loading all of it into memory wouldn't be feasible. We did get some solutions, a lot of brute force attempts but one guy in particular had some very interesting solutions for most of the problems.
I am not quite certain what cutting the problem up into discrete packages gives you, aside from the risk of never finding your duplicate.
Under the altered conditions, some measure must be taken to reduce memory usage. Portej's solution requires, in a pessimistic case, 9.87*10^282 bytes of memory, if not more due to oerhead. This is at best impractical.
I would really like to see the winning solution, though.