cactus.lua

local l,w = ...
for i=1,3 do turtle.up() end
local b=true
local s=0
local function rotate()
    if b then
        turtle.turnRight()
        turtle.forward()
        turtle.turnRight()
        s=1
    else
        turtle.turnLeft()
        turtle.forward()
        turtle.turnLeft()
        s=2
    end
    b=not b
end

for i=1,w do
    local dl
    if s==1 then dl=l-1 else dl=l end
    for i=1,dl do
    if s==0 then
        turtle.forward()
        turtle.forward()
    elseif s==1 then
        turtle.forward()
    else
        turtle.back()
    end

    turtle.digDown()
    turtle.down()
    turtle.digDown()
    turtle.up()
    s=0
    end
    rotate()
end