platprog_mc

function refuel()
    if turtle.getFuelLevel() == 0 then
        turtle.select(1)
        turtle.refuel(1)
        if turtle.getFuelLevel() == 0 then
            error("Out of fuel.")
        end
    end
end

function selectFirstFullSlot()
    for i = 2, 16 do
        if turtle.getItemCount(i) > 0 then
            turtle.select(i)
            return
        end
    end
end

function placeFirstAvailableBlock()
    selectFirstFullSlot()
    refuel()
    turtle.placeDown()
end

-- Program that builds a platform of size w by h
-- and then returns to the starting position.

print("Enter width and height:")
local w = 10
local h = 10

-- Read the width and height.
w = tonumber(io.read())
h = tonumber(io.read())

-- Build the platform.
for i = 1, w do
    for j = 1, h do
        placeFirstAvailableBlock()
        turtle.forward()
    end
    for j = 1, h do
        turtle.back()
    end
    if i < w then
        turtle.turnRight()
        turtle.forward()
        turtle.turnLeft()
    end
end

-- Return to the starting position.
turtle.turnLeft()
for i = 1, w do
    turtle.forward()
end
turtle.turnLeft()