放狗？为什么叫放狗？

belle1223

求问楼主“
a circuit has few conjunction points: A, B, C, D, E, and the connections from one to another is listed in a table:

A-E 3

E-D 2

A-B 1

B-D 2

so how many ways from A to D given that no points will be passed twice”
这道题什么意思啊……没太明白= =