## 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?