turtle - build tower

local curLevel = 0
local backStep = 0
local x = 0
local turns = 0

local loop = true

function shouldPlaceBlock()
    if (curLevel == 4) then
        return true
    elseif (backStep == 1) then
        return true
    end
end

while (loop) do
    if ( shouldPlaceBlock() ) then
        turtle.place()
    end

    turtle.back()
    backStep = backStep + 1

    if ( shouldPlaceBlock() ) then
        turtle.place()
    end

    if (turns >= 3) then
        turtle.up()
        curLevel = curLevel + 1
        turns = 0
    end
    if (curLevel > 4) then
        curLevel = 0
    end

    if (x == 0 and backStep == 15) then
        x = 1
        turtle.turnLeft()
        backStep = 0
        turns = turns + 1
    elseif (x == 1 and backStep == 22) then
        x = 0
        turtle.turnLeft()
        backStep = 0
        turns = turns + 1
    end
end