We have studied a variety of classic algorithms which esentially do the same thing: searching or sorting.

Here is a visual of some sorting algorithms in action.

So how do computer scientists choose which algorithm to use for a given scenario?

One strategy is to use Big O notation.

Big O notation is a way to describe how efficiently a program runs.

• Time complexity tells us how the running time of a program changes as the size of the input grows.
• Space complexity tells us how the memory use of a program changes as the input grows.

In short, Big O helps us compare how fast or memory-efficient different algorithms are, especially when the input becomes very large.

Study Guide