Given this tic-tac-toe position, as played by two expert players, who went first and where? Also, which was the last "move"?
X | O | O
---+---+---
| | X
---+---+---
| X | O
(An expert player is a player who would never play in such a way that would allow his opponent to win, and who would also try to get the possible best result.)
First, if it was X's turn, he could play middle left, and win -- since all matches should be draws, then it follows that it must be O's turn, and O played first.
If O had played at a corner, X would have had to answer in the center -- or otherwise O could have forced a win. So the first question is completely answered thus: "O started, playing top middle."
X couldn't have answered middle right, for O would won playing center. However, X playing top left or bottom middle do not allow for wins.
I found out more than a possible sequence, but they all end with X playing middle right, so that's the second answer.
Starting to work...
