In chapter eight of "An Introduction to the Analysis of Algorithms" by Sedgewick (1996 edition) the problem of the coupon collector on page 425 is presented.
My confusion is how can I identify the k collections. A k collection is defined as:
"a word consisting of k different letters, where the last letter of the word is the only time the letter occurs"
In Exercise 8.6 of the book, all 2 collections and 3 collections are found in Table 8.1. There the configurations of 4 balls are displayed in 3 urns
If I try, I would say a 3-collection from Table 8.1 is 2213, with the last letter (number 3) just ending, but I'm pretty sure I'm wrong.
Can anyone help provide an example of a k collection (2 or 3 collection) from Table 8.1? Many Thanks