"Flipping" Dimes and Pennies

[bonanova 81]

Place two dimes and two pennies in a line with a space between them like this:

 P P   D D
 _ _ _ _ _

Using a sequence of moves, switch the two groups of coins to achieve this position:

 D D   P P
 _ _ _ _ _

Moves are of two types:

1. slide a coin to an (adjacent) empty space.
2. jump a coin over another coin into an empty space.

Type (1) move:

 P P D   D
 _ _ _ _ _

Type (2) move:

 P   D P D
 _ _ _ _ _

The underlines show the (only) five legal locations for the coins to occupy.

What is the smallest number of moves needed?

[CaptainEd 21]

I can do it in 8

PP_DD

PPD_D

P_DPD

_PDPD

DP_PD

DPDP_

DPD_P

D_DPP

DD_PP

[Wilson 14]

Agree, best I  can do is 8.