gwd-6-22 不明白, 还有哪有排列组合题可以练练

看过仅有的一个讨论, 还是不明白. 另外哪有排列组合题, 我最怕这个了.

Q22:A certain company assigns employees to offices in such a way that

some of the offices can be empty and more than one employee can be

assigned to an office. In how many ways can the company assign 3

employees to 2 different offices?

A. 5

B. 6

C. 7

D. 8

E. 9

我的理解:

每人都可以选任一办公室,所以C(2,1)*C(2,1)*C(2,1)=8.

設有ABC三人，可assign 到兩個不同辦公室的組合如下:

1. 0; ABC

2. A; BC

3. AB; C

4. AC; B

5. B; CA

6. BC; A

7. C; AB

8. ABC; 0