Array Patterns

Now we need to check columns and diagonals too.

Column Layout:

Column 0: positions 0, 3, 6
Column 1: positions 1, 4, 7
Column 2: positions 2, 5, 8

Pattern: board[i], board[i+3], board[i+6]

Diagonal Layout:

Top-left to bottom-right: positions 0, 4, 8

Top-right to bottom-left: positions 2, 4, 6

Your Task:

Add three more checks to your checkWin function:

1. Loop through 3 columns (same pattern as rows, but with i, i+3, i+6)

2. Check diagonal 0, 4, 8

3. Check diagonal 2, 4, 6

Keep all the existing row checking code and add the column and diagonal checks after it.

Add column and diagonal checks

14%

Requirements:

Has column checking loop

Checks column positions

Checks column cell not Empty

Checks diagonal 0, 4, 8

Checks diagonal 2, 4, 6

Returns true for column match

Returns true for diagonal matches

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract TicTacToe {
    address public playerX;
    address public playerO;

    enum Cell { Empty, X, O }

    Cell[9] public board;

    bool public xTurn;

    function startGame(address _opponent) public {
        playerX = msg.sender;
        playerO = _opponent;
        xTurn = true;
    }

    function makeMove(uint _position) public {
        require(_position < 9, "Invalid position");
        require(board[_position] == Cell.Empty, "Cell already taken");
        require(xTurn ? msg.sender == playerX : msg.sender == playerO, "Not your turn");

        Cell piece = xTurn ? Cell.X : Cell.O;
        board[_position] = piece;

        xTurn = !xTurn;
    }

    function checkWin() private view returns (bool) {
        // Check rows
        for (uint i = 0; i < 3; i++) {
            if (board[i*3] != Cell.Empty &&
                board[i*3] == board[i*3+1] &&
                board[i*3] == board[i*3+2]) {
                return true;
            }
        }

        // Add column checks here

        // Add diagonal checks here

        return false;
    }

    function checkDraw() private view returns (bool) {
        for (uint i = 0; i < 9; i++) {
            if (board[i] == Cell.Empty) {
                return false;
            }
        }
        return true;
    }
}