floor place

local selectedSlot = 1
local first = true

while true do
    if not first then
        local forward = turtle.detect()
        local down = turtle.detectDown()

        if turtle.getItemCount(selectedSlot) == 0 then
            selectedSlot = selectedSlot + 1
        end

        if down then
            turtle.back()
            turtle.turnRight()
            turtle.forward()
        end
        elseif forward then turtle.turnRight()
        elseif not forward and not down then
            turtle.placeDown()
            turtle.forward()
        end
    else first = false
    end
end