This week we're going to dive into the course programming project. In the first lesson you'll learn about Strings and Regular Expressions, and in the programming assignment this week you'll apply that knowledge to adding functionality to your text editor so that it can measure the "readability" of text by calculating something called the "Flesch Readability Score". This course is focused on building code that not only does interesting things, but also finishes them quickly. So, let's get started building some code!

Welcome to week 3! The text-editor application you worked with last week does something, but it doesn't do it particularly fast. This week we'll start talking about efficiency. We'll introduce the concept of "Big-O" notation, which sounds a little silly, but is really a powerful (and extremely common) way of analyzing a program's efficiency, independent of the system that it's running on and the exact details of how it's implemented. Then we'll go the other direction and dive into the details, talking about how to measure the actual running time of a piece of code to get an idea of how it really performs in practice.

This week we'll start talking about some of the basic concepts that one expects to find in a data structures course: the idea of data abstraction, and a data structure called a Linked List. Even though Linked Lists are not very efficient structures (for the most part), they do hit home the idea of "linking" pieces of data together in your computer's memory, rather than storing the data in one contiguous region. This linking idea will be central to many of the more advanced data structures, namely trees and graphs, that are coming up later in this course and in the next course in this specialization. In this module you'll also learn tools and procedures for unit testing your code, which is a way to make sure that what you've written is correct, and a staple practice of any sophisticated software developer.

Welcome to week 4! We know you've been working hard. We hope you tried that optional Markov Text Generation programming assignment last week, but if not, no worries. You can always go back and do it later (spoiler alert: it's pretty amazing that such a simple algorithm can produce such realistic text). This week there's more fun (and hard work) as we learn about trees. Trees rely on the same linked structure idea as Linked Lists, only they're MUCH faster (usually...). In the project this week you'll add auto-complete to your text editor. Believe us when we say it's so cool when you get it working! You'll see... and we bet you can't wait for the programming assignment now. :)

You made it to the last week! Congratulations on getting this far! In this last week we'll be looking at a fundamental data structure called a Hash Table. If you thought trees were fast, just wait until you see what Hash Tables can do! Your last programming assignment will add spelling correction suggestions to your text editor, and there's an optional assignment that builds on the same ideas as the main assignment too, if you have the time and energy.