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1. Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

    const int kBoardLength = 3;
    const int kBoardSize = kBoardLength * kBoardLength;
   

2. Your test for unreachability is not complete. You verify that O has made no more moves than X, but you really need to check that the winner made the last move. If X won, then should have numberOfX = numberOfO + 1; if O won then should have numberOfO = numberOfX. It should be clear how to add these checks to your CheckTicTacToeBoard method.

3. A more overarching tension in this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

• Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

• Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 4-by-4 tic tac toe, the following state is unreachable, but not detected by your code:

        x x x x
        o o o o
        x x x x
        o o o o
  

1. Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

    const int kBoardLength = 3;
    const int kBoardSize = kBoardLength * kBoardLength;
   

2. Your test for unreachability is not complete. You verify that O has made no more moves than X, but you really need to check that the winner made the last move. If X won, then should have numberOfX = numberOfO + 1; if O won then should have numberOfO = numberOfX. It should be clear how to add these checks to your CheckTicTacToeBoard method.

3. A more overarching tension in this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

• Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

• Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 5-by-5 tic tac toe, the following state is unreachable, your code would return Xwins:

        x x x x x
        o . o . o
        x x x x x
        o . o . o
        o o x o o
  

1. Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

const int kBoardLength = 3;
const int kBoardSize = kBoardLength * kBoardLength;

2. Your test for unreachability is not complete. You verify that O has made no more moves than X, but you really need to check that the winner made the last move. If X won, then should have numberOfX = numberOfO + 1; if O won then should have numberOfO = numberOfX. It should be clear how to add these checks to your CheckTicTacToeBoard method.

3. A more overarching tension is this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

   i. Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

   ii. Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 4-by-4 tic tac toe, the following state is unreachable, but not detected by your code:

x x x x
o o o o
x x x x
o o o o

1. Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

    const int kBoardLength = 3;
    const int kBoardSize = kBoardLength * kBoardLength;
   

2. Your test for unreachability is not complete. You verify that O has made no more moves than X, but you really need to check that the winner made the last move. If X won, then should have numberOfX = numberOfO + 1; if O won then should have numberOfO = numberOfX. It should be clear how to add these checks to your CheckTicTacToeBoard method.

3. A more overarching tension in this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

• Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

• Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 4-by-4 tic tac toe, the following state is unreachable, but not detected by your code:

        x x x x
        o o o o
        x x x x
        o o o o
  

Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

const int kBoardLength = 3;
const int kBoardSize = kBoardLength * kBoardLength;

A more overarching tension is this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

1. Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

2. Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 4-by-4 tic tac toe, the following state is unreachable, but not detected by your code:

x x x x
o o o o
x x x x
o o o o

1. Computing a square-root is unnecessary; further, it only works when kBoardSize is a perfect square. Prefer

const int kBoardLength = 3;
const int kBoardSize = kBoardLength * kBoardLength;

2. Your test for unreachability is not complete. You verify that O has made no more moves than X, but you really need to check that the winner made the last move. If X won, then should have numberOfX = numberOfO + 1; if O won then should have numberOfO = numberOfX. It should be clear how to add these checks to your CheckTicTacToeBoard method.

3. A more overarching tension is this code is: should the board size really be a constant? The code is written so abstractly as to support any board size. But then the board size is fixed to a constant. I would choose one of the following directions to proceed in:

   i. Commit to a board size of 9. In this case, I would recommend hard-coding the win conditions in winDetection. There are only 8 ways to win, so the resulting code would be a lot cleaner.

   ii. Allow arbitrary board sizes. In this case, you should accept a boardLength argument. Further, you will have to refine the notion of an UnreachableState. For example, in 4-by-4 tic tac toe, the following state is unreachable, but not detected by your code:

x x x x
o o o o
x x x x
o o o o