Who should be the winner? Part II

Andy has a winning strategy. He starts by placing an X in the center of the board, square (5, 5). After that, his moves are symmetric to Bob's move. Specifically, if Bob plays in square $(a, b)$ , then Andy will play in square $(10-a, 10-b)$ . It is clear that if Bob can make a move, then so can Andy, so this strategy can continue till the end.

Now, let's consider what the score of the board is. Ignoring the 5th row and the 5th column, then row K awards a point to Andy if and only if row 10-K awards a point to Bob. Hence, they will both get a total of 8 points from the non-center rows and columns.

For the center row/column, since Andy played square (5,5) and acts symmetrically, it is clear that he will have 5 X's in it, and hence will get the points.
Thus, Andy wins with a score of 10 - 8.

Hence, Andy has a winning strategy.

The key to problems like these is looking for symmetry: meaning that, after the first move, the first person sort of mimics whatever the first person does, in reverse. So you chooses a line of symmetry that they want to play with. Lets say they pick a center column. They can then place anywhere along the center column as their first move, and then do whatever move is the reflection of their opponents move on subsequent moves. In the case where the second player places in your center column, you simply respond by placing anywhere in your center column.

At the end of the game, you will have won the center column, both you and your opponent will have 4 of each of the side columns, and since you are mirroring your opponents moves, if you look at any of the rows, both you and your opponent will have exactly 4 X's and 4 O's and whatever is in the middle column, and since you will have 5 things in the middle column and your opponent will 4 things in the middle column, you will also win 5 of the 9 rows, so the score will be 10-8.