# Solution Review: Is Unique

This lesson contains the solution review to determine whether a string contains all unique characters or not.

## We'll cover the following

In this lesson, we will consider how to determine if a string has all unique characters. One approach to this problem may be to use an additional data structure, like a hash table. We will also consider how one may solve this problem without the use of such a data structure.

So, we’ll present a number of solutions to the problem posed in the previous challenge and give a rough time and space complexity analysis of each approach.

Let’s get started!

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