Potential energy of an electric dipole

[Samanko]

Homework Statement

When three electric dipoles are near each other, they each experience the electric field of the other two, and the three-dipole system has a certain potential energy. Figure shows two arrangenents in which three electric dipoles are side by side. Each dipole has the same magnitude of electric dipole moment, and the spacings between adjacent dipoles are identical. In which arrangrment is the potential energy of the three-dipole system greater?

Relevant Equations

U = - p • E

This is a problem from a textbook, and I can't solve it.
I know that the equation of Potential energy of electric dipole. Since the configuration is a little bit complicated. I'm confused applying which electric fields.

 

[BvU]

I'm confused applying which electric fields

Try the following: place the center dipole in its position, leave the other two at infinity (e.g. to left and right). Now bring those two closer until you have the final configuration. Which way does $\vec E$ point ? So which of (a) and (b) is easier (cheaper, lower energy) ?

 

[Samanko]

Try the following: place the center dipole in its position, leave the other two at infinity (e.g. to left and right). Now bring those two closer until you have the final configuration. Which way does $\vec E$ point ? So which of (a) and (b) is easier (cheaper, lower energy) ?

Thank you!