Pacman: how do the eyes find their way back to the monster hole?

Question

I found a lot of references to the AI of the ghosts in Pacman, but none of them mentioned how the eyes find their way back to the central ghost hole after a ghost is eaten by Pa

Answer 1

Here's an analog and pseudocode to ammoQ's flood fill idea.

queue q
enqueue q, ghost_origin
set visited

while q has squares
   p <= dequeue q
   for each square s adjacent to p
      if ( s not in visited ) then
         add s to visited
         s.returndirection <= direction from s to p
         enqueue q, s
      end if
   next
 next

The idea is that it's a breadth-first search, so each time you encounter a new adjacent square s, the best path is through p. It's O(N) I do believe.