Suppose (ideally… again, ideally) that you have created different algorithms to solve a particular problem. Now, suppose that you have determined the order for those algorithms using Big-O notation. Which algorithm performs better?

This ABC goes like this:

**O(1) < O(log N) < O(N) < O(N log N) < O(N^2) < O(2^N) < O(N!) < O(N^N)**

*Constant*running time is the best… then

*logarithmic*,

*linear*,

*linearithmic*,

*quadratic*,

*exponential*,

*factorial*and I leave the name of the last one to you :-)

Having

*constant*,*logarithmic*and*linear*algorithms should be you goal, although this might be difficult to achieve. In real world problems, if your solution algorithm is higher than*quadratic*, I would advise you to drop it…I have seen lots of people get frozen with a simple question: which function grows faster? Remember the correlation above…it’s easy.

Notice: Having a

**O(1)**,**O(log N)**or**O(N)**algorithm doesn’t guarantee that your code is well written or optimized. Even with those orders there might be place for improvements and refactoring.
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