A Common-Sense Guide to Data Structures and Algorithms, Second Edition, 2nd Edition

Sets: How a Single Rule Can Affect Efficiency

Let’s explore another data structure: the set. A set is a data structure that does not allow duplicate values to be contained within it.

There are different types of sets, but for this discussion, I’ll talk about an array-based set. This set is just like an array—it is a simple list of values. The only difference between this set and a classic array is that the set never allows duplicate values to be inserted into it.

For example, if you had the set ["a", "b", "c"] and tried to add another "b", the computer just wouldn’t allow it, since a "b" already exists within the set.

Sets are useful when you need to ensure that you don’t have duplicate data.

For instance, if you’re creating an online phone ...