The ACM contests aren't the best guage; they only reflect a few individuals' talents. That's why you get schools that aren't even Top 20 by U.S. News in comp sci getting placed near the top; they have a few extremely bright students.
Also, for the one who requested the U.S. News rankings, no one ranks undergrad comp sci programs, only grad. But if you want to use grad rankings, then the following are among the top 20 off the top of my head:
Harvard
Cornell
MIT
Caltech
UTexas
UIUC
Berkeley
Princeton
Rice
UMich
CMU
Stanford
Brown
A lot of the above teach theoretical CS quite well, and a lot of them use Scheme for starters (MIT, Rice, Caltech, etc.; Rice developed Dr. Scheme, which is the compiler used in most places, and MIT actually developed the Scheme language).
Anyway, go get a book or talk to people. Rankings don't mean as much as actual reputaiton and job placements, if that's what you're concerned about. For instance, Harvard isn't ranked very highly, but I'm sure a CS degree from harvard is worth a good bit. Rice isn't ranked as high as some of the state schools, but in the south they're among the most respected (because of program rigor). Places like Columbia aren't ranked that high (not top 20, even), but it's in NYC, so internship and job placement opps are top-notch. I chose my school based on overall undergrad quality, prestige and student body, not strength of a specific undergrad program. And I'm quite satisfied (I was accepted to 2 schools in the top 10 comp sci, turned them both down to do physics at a different school).
It depends on preference. Good luck!