Coding classes in Northamptonshire

The learner builds an invented 30-floor building with one lift. Floors are 3.5 metres apart and the lift moves at 7 metres per second, the top speed the Northampton tower was built to test, so each floor takes half a second, and every stop costs 12 seconds for doors and people. Three hundred calls arrive at random times, a third of them from the ground floor. The program then tries three rules. First come, first served answers calls strictly in order. Nearest first always goes to the closest waiting call. The LOOK rule, often called the elevator algorithm, keeps travelling in one direction while anyone ahead is waiting, then turns round.

Nearest first looks efficient: it travels only 616 floors, well under half the distance of first come, first served, and its average wait is a little lower. But its longest wait is 734.5 seconds, more than twelve minutes, because while calls keep appearing near the lift, someone at the far end is never the closest. Computer scientists call this starvation. LOOK travels almost as little, has the lowest average wait of the three, and keeps the longest wait to 337.4 seconds, because a lift that sweeps up and down must reach every floor eventually.

In a quiet period, with a call every 30 seconds, the three rules are much closer: averages of 16.7, 14.1 and 14.0 seconds. Rules only really show their character when the system is under pressure. That is the second lesson: test a design at its busiest, and judge it by the unluckiest user as well as the average one.

So a young person in Northamptonshire should learn to code in 2026 to check who a clever system leaves waiting. The longer argument is in why teenagers should still learn to code in 2026.