Archive for October, 2010

by the elevator

The instructions, by the way, are at http://phdchallenge.com, which got cut off.

different kind of coupon collector’s problem

The classic coupon collector’s problem asks for the number of samples it takes to collect all coupon types from a sequence of coupons in which each of the \(k\) types of coupons has an unlimited number of copies.

Here is a different kind of problem: if there are limited copies of each of the \(k\) coupon types (say, \(d\) copies), how many samples does it take to collect \(t\) coupon types?

(Read the article)

copycat sites

facebook
http://jeremy.zawodny.com/i/facebook-profile.jpg
xiaonei
http://soft.yesky.com/imagelist/2008/016/8t1dt736bw55.jpg
twitter
http://www.techxav.com/wp-content/uploads/external/farm4.static.flickr.com/3443/3391630305_6b5ae3f10f.jpg
fanfou
http://www.distilled.co.uk/blog/wp-content/uploads/2009/07/fanfou.jpg
digg
http://www.brentcsutoras.com/wp-content/uploads/2010/03/digg2-0.gif
chouti
http://img.cnbeta.com/newsimg/090116/09441831265372565.jpg

And some subtler ones:
(Read the article)