Rou_bi's stats

-- aaden

print("Input current board")

local h = io.read()

local s = ""

local count = {
    ["."] = 0,
    ["x"] = 0,
    ["o"] = 0,
}

for i in string.gmatch(h, "([%.xo])") do
    s = s..i
    count[i] = count[i] + 1
end

function entry(board)
    local function format(string)
        return string.sub(string, 1, 3).."\n"..string.sub(string, 4, 6).."\n"..string.sub(string, 7, 9)
    end
    local function tile(x, y)
        return string.sub(board, x + ((y - 1) * 3), x + ((y - 1) * 3))
    end
    -- checking for valid horizontal wins
    for i=1, 3 do
        local period = 0
        for j=1, 3 do
            local slot = tile(j, i)
            if slot == "o" then
                period = -1
                break
            elseif slot == "." then
                period = period + 1
            end
        end

        if period == 1 then
            return format(string.sub(board, 0, (i - 1) * 3).."xxx"..string.sub(board, ((i + 1) * 3) + 1, -1))
        end
    end
    -- checking for valid vertical wins
    for i=1, 3 do
        local period = 0
        for j=1, 3 do
            local slot = tile(i, j)
            if slot == "o" then
                period = -1
                break
            elseif slot == "." then
                period = period + 1
            end
        end

        if period == 1 then
            return format(string.sub(board, 0, i - 1).."x"..string.sub(board, i + 1, i + 2).."x"..string.sub(board, i + 4, i + 5).."x"..string.sub(board, i + 7, -1))
        end
    end
    -- diagonal 1
    local period = 0
    for i=1, 3 do
        local slot = tile(4 - i, i)
        if slot == "o" then
            break
        elseif slot == "." then
            period = period + 1
        end

        if i == 3 and period == 1 then
            return format(string.sub(board, 1, 2).."x"..string.sub(board, 4, 4).."x"..string.sub(board, 6, 6).."x"..string.sub(board, 8, 9))
        end
    end
    -- diagonal 2
    period = 0
    for i=1, 3 do
        local slot = tile(i, i)
        if slot == "o" then
            break
        elseif slot == "." then
            period = period + 1
        end

        if i == 3 and period == 1 then
            return format("x"..string.sub(board, 2, 4).."x"..string.sub(board, 6, 8).."x")
        end
    end
    -- doing the same for player O so player X can prevent it
    -- checking for valid horizontal wins
    for i=1, 3 do
        local period = 0
        local periodpos = {0, 0}
        for j=1, 3 do
            local slot = tile(j, i)
            if slot == "x" then
                period = -1
                break
            elseif slot == "." then
                period = period + 1
                periodpos = {j, i}
            end
        end

        if period == 1 then
            return format(string.sub(board, 0, (periodpos[1] - 1) + ((periodpos[2] - 1) * 3)).."x"..string.sub(board, (periodpos[1] + 1) + ((periodpos[2] - 1) * 3), -1))
        end
    end
    -- checking for valid vertical wins
    for i=1, 3 do
        local period = 0
        local periodpos = {0, 0}
        for j=1, 3 do
            local slot = tile(i, j)
            if slot == "x" then
                period = -1
                break
            elseif slot == "." then
                period = period + 1
                periodpos = {i, j}
            end
        end

        if period == 1 then
            return format(string.sub(board, 0, (periodpos[1] - 1) + ((periodpos[2] - 1) * 3)).."x"..string.sub(board, (periodpos[1] + 1) + ((periodpos[2] - 1) * 3), -1))
        end
    end
    -- diagonal 1
    period = 0
    local periodpos = {0, 0}
    for i=1, 3 do
        local slot = tile(4 - i, i)
        if slot == "x" then
            break
        elseif slot == "." then
            period = period + 1
            periodpos = {4 - i, i}
        end

        if i == 3 and period == 1 then
            return format(string.sub(board, 0, (periodpos[1] - 1) + ((periodpos[2] - 1) * 3)).."x"..string.sub(board, (periodpos[1] + 1) + ((periodpos[2] - 1) * 3), -1))
        end
    end
    -- diagonal 2
    period = 0
    periodpos = {0, 0}
    for i=1, 3 do
        local slot = tile(i, i)
        if slot == "x" then
            break
        elseif slot == "." then
            period = period + 1
            periodpos = {i, i}
        end

        if i == 3 and period == 1 then
            return format(string.sub(board, 0, (periodpos[1] - 1) + ((periodpos[2] - 1) * 3)).."x"..string.sub(board, (periodpos[1] + 1) + ((periodpos[2] - 1) * 3), -1))
        end
    end

    -- method 1
    if tile(3, 1) == "." and tile(3, 2) == "." and tile(1, 3) ~= "o" and tile(1, 2) ~= "o" and tile(2, 2) ~= "o" then
        if tile(1, 3) == "." then
            return format(string.sub(board, 1, 6).."x"..string.sub(board, 8, 9))
        elseif tile(1, 2) == "." then
            return format(string.sub(board, 1, 3).."x"..string.sub(board, 5, 9))
        elseif tile(2, 2) == "." then
            return format(string.sub(board, 1, 4).."x"..string.sub(board, 6, 9))
        end
    end
    -- method 2
    if tile(2, 2) == "o" then
        if tile(3, 1) == "." then
            return format(string.sub(board, 1, 2).."x"..string.sub(board, 4, 9))
        elseif tile(1, 1) == "." then
            return format("x"..string.sub(board, 2, 9))
        elseif tile(3, 3) == "." then
            return format(string.sub(board, 1, 8).."x")
        elseif tile(1, 3) == "." then
            return format(string.sub(board, 1, 6).."x"..string.sub(board, 8, 9))
        end
    end

    local candidates = {}

    for i=1, 9 do
        if string.sub(board, i, i) == "." then
            candidates[#candidates+1] = i
        end
    end

    if #candidates > 0 then
        local chosen = candidates[math.random(1, #candidates)]

        return format(string.sub(board, 0, chosen - 1).."x"..string.sub(board, chosen + 1, 9))
    else
        return "Nothing to do..."
    end
end

print(entry(s))