I made this poster after seeing (and retweeting) this from @CompSciFact, whom you should be following:
‘Fancy algorithms are slow when n is small, and n is usually small.’ — Rob Pike
— Computer Science (@CompSciFact) December 2, 2014
It’s the most amusing of Rob Pike’s 5 Rules of Programming, which are listed below:
- You can’t tell where a program is going to spend its time. Bottlenecks occur in surprising places, so don’t try to second guess and put in a speed hack until you’ve proven that’s where the bottleneck is.
- Measure. Don’t tune for speed until you’ve measured, and even then don’t unless one part of the code overwhelms the rest.
- Fancy algorithms are slow when n is small, and n is usually small. Fancy algorithms have big constants. Until you know that n is frequently going to be big, don’t get fancy. (Even if n does get big, use Rule 2 first.)
- Fancy algorithms are buggier than simple ones, and they’re much harder to implement. Use simple algorithms as well as simple data structures.
- Data dominates. If you’ve chosen the right data structures and organized things well, the algorithms will almost always be self-evident. Data structures, not algorithms, are central to programming.
It’s a good set of general rules to keep in mind.