How can I check if the first row of a 2D array with no fixed dimension all have the same value?

Question

I'm making a tic tac toe game in Java with a customizable dimension feature (user can choose to play 3x3, 4x4, 5x5, etc.) and was working on the logic regarding finding a winner. Currently I'm trying to figure out checking for wins horizontally.

I've had the idea to make a nested for-loop to check the 2d array that hosts the board, but am not sure how to execute this. The problem with this code:

for (int i = 0; i < dimension; i++) {
        if (board[i][0] == board[i][1] && board[i][1] == board[i][2] && board[i][0] != '-') {
                // you won!
        }
}

...Is that its logic is fixed for a 3x3 game, not for any other dimensions. I only know how to add values into 2d arrays, so how can I check if these values are equal? Thank you in advance.

Answer 1

I'm not sure about the rules for winning tic tac toe in higher dimensions, so let's say you have to fill the whole row/column to win.

Divide the if in two parts: The check for the first chararacter and the comparisons. Then use a second for-loop for the comparisons, like this:

for (int i = 0; i < dimension; i++) { // iterate rows
    // check for first character
    if (board[i][0] == '-') {    // if wrong character...
        continue;                // ... check next row
    }

    boolean won = true;

    for (int j = 0; j < dimension - 1; j++) { // iterate columns
        if (board[i][j] != board[i][j+1]) {   // if other character...
            won = false;                      // ...not winnable with this column and...
            break;                            // ...stop iteration of columns
        }
    }

    if (won) {
        // you won!
    }
}

If you win with less crosses 'X' in all dimensions, you would have to add a third loop to go through the possible start points or you could count the amount of crosses in the column and reset the number if there is an 'O'.