tic-tac-toe.jl

#############################
# Tic-tac-toe game in Julia #
#############################


wins = [[[1, 1], [1, 2], [1, 3]],
        [[2, 1], [2, 2], [2, 3]],
        [[3, 1], [3, 2], [3, 3]],
        [[1, 1], [2, 1], [3, 1]],
        [[1, 2], [2, 2], [3, 2]],
        [[1, 3], [2, 3], [3, 3]],
        [[1, 1], [2, 2], [3, 3]],
        [[1, 3], [2, 2], [3, 1]]]


function print_board(board)
    println(" _ " ^ 3)
    for i in 1 : 3
        println(board[i])
    end
end


function display_board(moves_a, moves_b)
    display = []
    for i in 1 : 3
        display_row = ""
        for j in 1 : 3
            if [i, j] in moves_a
                display_row *= "|$player_a|"
            elseif [i, j] in moves_b
                display_row *= "|$player_b|"
            else
                display_row *= "|_|"
            end
        end
        push!(display, display_row)
    end
    print_board(display)
end


function evaluate(moves_a, moves_b)
    status, a_b = check_win(moves_a, moves_b)
    if status
        if a_b == player_b
            return 10
        else
            return -10
        end
    end
    return 0
end


function minmax(moves_a, moves_b, depth, ismax)
    scr = evaluate(moves_a, moves_b)
    if scr == 10
        return scr
    end
    if scr == -10
        return scr
    end
    if length(moves_a) + length(moves_b) >= 9
        return 0
    end
    if ismax
        best = -1000
        for i in 1 : 3, j in 1 : 3
            if !([i, j] in moves_a) &&
               !([i, j] in moves_b)
               push!(moves_b, [i, j])
               best = max(best, minmax(moves_a, moves_b,
                                       depth + 1, !ismax))
               pop!(moves_b)
            end
        end
        return best
    else
        best = 1000
        for i in 1 : 3, j in 1 : 3
            if !([i, j] in moves_a) &&
               !([i, j] in moves_b)
               push!(moves_a, [i, j])
               best = min(best, minmax(moves_a, moves_b,
                                       depth + 1, !ismax))
               pop!(moves_a)
            end
        end
        return best
    end
end


function move_comp(moves_a, moves_b)
    best_val = -1000
    best_move = [-1, -1]
    for i in 1 : 3, j in 1 : 3
        if !([i, j] in moves_a) &&
           !([i, j] in moves_b)
           push!(moves_b, [i, j])
           mval = minmax(moves_a, moves_b, 0, false)
           pop!(moves_b)
           if mval > best_val
               best_move = [i, j]
               best_val = mval
           end
       end
   end
   return best_move
end

function check_win(moves_a, moves_b)
    if any(x -> (all(y -> y in moves_a, x)), wins)
        return true, player_a
    end
    if any(x -> (all(y -> y in moves_b, x)), wins)
        return true, player_b
    end
    return false, player_a
end

function play()
    println("Select Player:\n1. X\n2. O")
    char = 1
    try
        char = parse(Int64, readline(stdin))
    catch
        println("Invalid choice.")
        exit(0)
    end
    if char != 1 && char != 2
        println("Invalid choice.")
        exit(0)
    end
    global char_dict = Dict(1 => 'X', 2 => 'O')
    global player_a = char_dict[char]
    global player_b = (player_a == 'X') ? 'O' : 'X'
    println("Player $player_b:\n1. Human\n2. Computer")
    opponent = 1
    try
        opponent = parse(Int64, readline(stdin))
    catch
        println("Invalid choice.")
        exit(0)
    end
    if opponent != 1 && opponent != 2
        println("Invalid choice.")
        exit(0)
    end
    moves_a = []
    moves_b = []
    cnt = 0

    while length(moves_a) + length(moves_b) < 9
        display_board(moves_a, moves_b)
        player = (cnt % 2 == 0) ? 'X' : 'O'
        if player != player_a && opponent == 2
            comp_move = move_comp(moves_a, moves_b)
            push!(moves_b, comp_move)
            println("Computer made the following move: $comp_move")
            cnt += 1
            continue
        end
        print("Player $player Enter your move in `row col` format: ")
        move_x, move_y = 0, 0
        try
            moves = split(readline(stdin), ' ')
            move_x = parse(Int64, moves[1])
            move_y = parse(Int64, moves[2])
        catch
            println("Invalid syntax.")
        end
        if move_x < 1 || move_x > 3 ||
           move_y < 1 || move_y > 3
           println("Invalid move.")
           continue
       end
       if player == player_a
           if !([move_x, move_y] in moves_a) &&
              !([move_x, move_y] in moves_b)
               push!(moves_a, [move_x, move_y])
               cnt += 1
           else
               println("Move already made. Try again.")
               continue
           end
       else
           if !([move_x, move_y] in moves_a) &&
              !([move_x, move_y] in moves_b)
               push!(moves_b, [move_x, move_y])
               cnt += 1
           else
               println("Move already made. Try again.")
               continue
           end
       end
       status, a_b = check_win(moves_a, moves_b)
       if status
           display_board(moves_a, moves_b)
           println("\n***Player $a_b has won!***")
           exit(0)
       end
    end
    println("\n***This is a draw.***")
end

play()