Answer: Game playing

Question: What is the game tree for the following Connect-3 board?

  X..   ('.' represents an empty box)
  X..
  OOX

Answer:

          X..
          X..
     _____OOX_____
    /      1      \
   X..           X..
   XO.           X.O
  _OOX__         OOX_
 /  1   \       / 1  \
XX.    X..     X..  X.X
XO.    XOX     XXO  X.O
OOX    OOX     OOX  OOX
 1    /-1 \     1    1
 |    |    |         |
XX.  XO.  X.O       X.X
XOO  XOX  XOX       XOO
OOX  OOX  OOX       OOX
 1   -1   -1         1
 |                   |
XXX                 XXX
XOO                 XOO
OOX                 OOX
 1                   1