In today's lesson, we'll dive into the world of Python sets. We'll focus on leveraging this powerful data structure to solve two common interview problems. Sets' ability to handle unique elements can simplify and optimize our problem-solving process, making it more efficient. So, if you're ready to discover the power and nuances of using sets to solve problems, let's get started!

Our first problem revolves around identifying the first unique string from a list. Imagine you're working on a text analyzing tool that needs to identify the first unique word in a piece of text. This problem simulates such a real-world scenario.

At first glance, a naive approach would be to iterate over the list of words and, for each word, scan the entire list again to count its occurrences. This method of double-pass scanning the list results in an unsightly time complexity of $O(N^2)$ as each word incurs another full traverse. As the list grows in size, the time taken by this approach grows exponentially, making it impractical for larger datasets.