You Do Need power plug adapter while traveling from Andorra to Switzerland.

Here is Why You Need An Adapter

The outlet and plug type used in Switzerland are C and J and in Andorra are C and F. This is how they look like.

Andorra

In Andorra, outlets of type C and F are in use.

Type C

Type F

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J