Maze marker

local steps = 0

function placeCheckPoint()
  turtle.select(1)
  turtle.digDown()
  turtle.down()
  turtle.select(2)
  turtle.digDown()
  turtle.down()
  turtle.select(3)
  turtle.digDown()
  turtle.down()
  turtle.down()
  turtle.placeDown()
  turtle.up()
  turtle.up()
  turtle.up()
  turtle.select(2)
  turtle.placeDown()
  turtle.up()
  turtle.select(1)
  turtle.placeDown()
  turtle.digUp()
  turtle.select(5)
  turtle.placeUp()
end

function step()
  if tryForward() or tryLeft() or tryRight() then
    steps = steps + 1
    if steps > 18 then
      placeCheckPoint()
      steps = 0
    end
  else
    print('Path: '..steps.." steps length")
    exit()
  end
end

function isWay()
  turtle.detectUp()
end

function tryForward()
  if turtle.forward() then
    if turtle.detectUp() then
      return true
    else
      turtle.back()
      return false
    end
  else
    return false
  end
end

function tryLeft()
  turtle.turnLeft()
  if tryForward() then
    return true
  else
    turtle.turnRight()
    return false
  end
end

function tryRight()
  turtle.turnRight()
  if tryForward() then
    return true
  else
    turtle.turnLeft()
    return false
  end
end

while true do
  step()
end