minmax tic-tac-toe full code in matlab

main.m
function [score, depth] = minmax(board, player, level)
    % MINMAX is a recursive function that uses the minmax algorithm to find
    % the optimal move for the player given the current board state
    
    % Initialize the score and depth
    score = 0;
    depth = level;
    
    % Check if the game is over or if the maximum depth level is reached
    if check_game_over(board) || level == 0
        score = evaluate_board(board, player);
        return
    end
    
    % If the player is X (maximizer), get the maximum possible score
    if player == 'X'
        for i = 1:3
            for j = 1:3
                if board(i,j) == ' '
                    tmp_board = board;
                    tmp_board(i,j) = 'X';
                    [~, tmp_depth] = minmax(tmp_board, 'O', level-1);
                    if tmp_depth < depth
                        depth = tmp_depth;
                    end
                    if score < evaluate_board(tmp_board, 'X')
                        score = evaluate_board(tmp_board, 'X');
                    end
                end
            end
        end
    % If the player is O (minimizer), get the minimum possible score
    else
        for i = 1:3
            for j = 1:3
                if board(i,j) == ' '
                    tmp_board = board;
                    tmp_board(i,j) = 'O';
                    [~, tmp_depth] = minmax(tmp_board, 'X', level-1);
                    if tmp_depth < depth
                        depth = tmp_depth;
                    end
                    if score > evaluate_board(tmp_board, 'O')
                        score = evaluate_board(tmp_board, 'O');
                    end
                end
            end
        end
    end
end

function [result] = check_game_over(board)
    % CHECK_GAME_OVER checks if the game is over and returns the result
    
    result = false;
    
    % Check for three in a row
    for i = 1:3
        if board(i,1) == board(i,2) && board(i,2) == board(i,3) && board(i,1) ~= ' '
            result = true;
            return
        end
    end
    
    % Check for three in a column
    for i = 1:3
        if board(1,i) == board(2,i) && board(2,i) == board(3,i) && board(1,i) ~= ' '
            result = true;
            return
        end
    end
    
    % Check for three in a diagonal
    if board(1,1) == board(2,2) && board(2,2) == board(3,3) && board(1,1) ~= ' '
        result = true;
        return
    end
    if board(1,3) == board(2,2) && board(2,2) == board(3,1) && board(1,3) ~= ' '
        result = true;
        return
    end
    
    % Check if the board is full
    if sum(sum(board == ' ')) == 0
        result = true;
        return
    end
end

function [score] = evaluate_board(board, player)
    % EVALUATE_BOARD returns a score for the board given the player
    
    % Initialize the score to 0
    score = 0;
    
    % Check for three in a row, column, or diagonal
    for i = 1:3
        if board(i,1) == board(i,2) && board(i,2) == board(i,3) && board(i,1) == player
            score = 10;
            return
        end
        if board(1,i) == board(2,i) && board(2,i) == board(3,i) && board(1,i) == player
            score = 10;
            return
        end
    end
    if board(1,1) == board(2,2) && board(2,2) == board(3,3) && board(1,1) == player
        score = 10;
        return
    end
    if board(1,3) == board(2,2) && board(2,2) == board(3,1) && board(1,3) == player
        score = 10;
        return
    end
    
    % Check for two in a row, column, or diagonal
    for i = 1:3
        if board(i,1) == board(i,2) && board(i,1) == player && board(i,3) == ' '
            score = 5;
            return
        end
        if board(i,1) == board(i,3) && board(i,1) == player && board(i,2) == ' '
            score = 5;
            return
        end
        if board(i,2) == board(i,3) && board(i,2) == player && board(i,1) == ' '
            score = 5;
            return
        end
        if board(1,i) == board(2,i) && board(1,i) == player && board(3,i) == ' '
            score = 5;
            return
        end
        if board(1,i) == board(3,i) && board(1,i) == player && board(2,i) == ' '
            score = 5;
            return
        end
        if board(2,i) == board(3,i) && board(2,i) == player && board(1,i) == ' '
            score = 5;
            return
        end
    end
    if board(1,1) == board(2,2) && board(1,1) == player && board(3,3) == ' '
        score = 5;
        return
    end
    if board(1,1) == board(3,3) && board(1,1) == player && board(2,2) == ' '
        score = 5;
        return
    end
    if board(2,2) == board(3,3) && board(2,2) == player && board(1,1) == ' '
        score = 5;
        return
    end
    if board(1,3) == board(2,2) && board(1,3) == player && board(3,1) == ' '
        score = 5;
        return
    end
    if board(1,3) == board(3,1) && board(1,3) == player && board(2,2) == ' '
        score = 5;
        return
    end
    if board(2,2) == board(3,1) && board(2,2) == player && board(1,3) == ' '
        score = 5;
        return
    end
    
    % If no winning or blocking move, return score of 0
end

function [] = print_board(board)
    % PRINT_BOARD prints the current state of the board
    
    fprintf('\n');
    for i = 1:3
        fprintf(' %s | %s | %s ', board(i,:));
        if i ~= 3
            fprintf('\n---+---+---\n');
        else
            fprintf('\n');
        end
    end
end

function [] = tic_tac_toe()
    % TIC_TAC_TOE is the main function that controls the game play
    
    % Initialize the board
    board = repmat(' ', 3, 3);
    
    % Prompt user for X or O
    player = input('Would you like to play as X or O? ', 's');
    
    % Initialize scores
    score_x = 0;
    score_o = 0;
    
    % Start game loop
    while sum(sum(board == ' ')) > 0 && check_game_over(board) == false
        % Print the board
        print_board(board);
        
        % Let the user make a move (if they are playing as X)
        if player == 'X'
            valid_move = false;
            while valid_move == false
                row = input('Enter the row number (1-3): ');
                col = input('Enter the column number (1-3): ');
                if board(row,col) == ' '
                    board(row,col) = 'X';
                    valid_move = true;
                else
                    fprintf('That space is already taken. Try again.\n');
                end
            end
        end
        
        % Use minmax algorithm to find the optimal move for O
        [score, ~] = minmax(board, 'O', 5);
        [row, col] = find(board == ' ' & evaluate_board(board, 'O') == score, 1);
        if isempty(row) % if there is no winning move, use minimax to block X's winning move
            [score, ~] = minmax(board, 'X', 5);
            [row, col] = find(board == ' ' & evaluate_board(board, 'X') == score, 1);
        end
        board(row,col) = 'O';
        
        % Update scores
        score_x = evaluate_board(board, 'X');
        score_o = evaluate_board(board, 'O');
    end
    
    % Print the final board and scores
    print_board(board);
    if check_game_over(board) && score_x ~= 10 && score_o ~= 10
        fprintf('The game is a tie.\n');
    elseif player == 'X' && score_x == 10
        fprintf('You win!\n');
    elseif player == 'O' && score_o == 10
        fprintf('You win!\n');
    else
        fprintf('The computer wins!\n');
    end
end
7462 chars
244 lines