Vox Codei - Episode 2: nodes direction

In this episode nodes are now moving! How to get nodes direction on start?
Thanks.

Observe the positions over several turns.
It is save to assume that

  • at the beginning all blocks are visible (no two blocks at the same location)
  • there is a unique way of moving (#@@# could be #→←# (swapping places) or #…# (both stationary), this case won’t occur)
  • you have enough turns to fully analyze the moment before placing the first bomb

Ok thanks eulerscheZahl.
Some test cases are hard to analyse (like #08: ‘indestructible nodes, 4 bombs’ where they all start in a same diagonal ans leave in different directions)