Boxi Learn › Computing › Stage 4 · Systems and Argument
Halve it: how search gets fast
CS-1 Break a big job into small stepsCS-2 Hand repeated work to a loopX-2 Evidence outweighs opinion
What many people think
A faster computer always beats a better algorithm.
The idea
Halving a sorted list each time finds one item among a million in about 20 looks.
Explain it
A friend says “just buy a faster computer, the method doesn’t matter.” Use the numbers for a list of a million to explain why halving still wins, and say when your friend is right.
Try at home
Ask someone to think of a number from 1 to 100 and answer only “higher” or “lower”. Play once guessing freely and once always guessing the middle; count the guesses. Then find a word in a paper dictionary by opening it in the middle and halving.