That algorithm doesn’t count steps of a stair, it counts the number of steps you take to go up (or down) a staircase.

Those are different if you follow this nerd’s way, which, by the way, has benefits other than making it easier to count stairs. It’s a fairly easy way to get some strength training. I think everybody who can should take stairs two steps at a time. That gives you some cushion in old age, as you’ll be able to go back to one step at a time, and postpones the day where taking a stair becomes impossible.

If two steps is easy, you can make going up harder (I don’t advise that going down stairs) by sitting deeper, with your thighs horizontally, or by taking three steps at a time (four steps is out of reach for most)