special voronoi selection

i want to select points out of a voronoi grid without there adjacting cells. (as you can see in the picture)

i am using the pmadjactingfaces component from the pt plugin to get a list of all adjacting cells for each cell. then i want to start with cell number (0). i check for all neighbor cells. in my example a list of (9,11,19,28,29). i start with the smallest number (9) and check again their adjacting cells to compare both list and set the difference....(16)....

(0,16) are my first two selections....I continuing in the same way. As you can see in my gh definition it stops at cell number 12, because there a no possibilities left.

I am searching for a way, if the definition is out of possibilities to go back one step and choose the second instead of the smallest number of a list.

I am sure that there is an other complete different and better solution to solve this selection problem....because if i would chance the number of points i have to chance the definition itself.

somebody any idea? 

cheers