#### Overview of this book

Data structures and algorithms are more than just theoretical concepts. They help you become familiar with computational methods for solving problems and writing logical code. Equipped with this knowledge, you can write efficient programs that run faster and use less memory. Hands-On Data Structures and Algorithms with Kotlin book starts with the basics of algorithms and data structures, helping you get to grips with the fundamentals and measure complexity. You'll then move on to exploring the basics of functional programming while getting used to thinking recursively. Packed with plenty of examples along the way, this book will help you grasp each concept easily. In addition to this, you'll get a clear understanding of how the data structures in Kotlin's collection framework work internally. By the end of this book, you will be able to apply the theory of data structures and algorithms to work out real-world problems.
Preface
Free Chapter
Section 1: Getting Started with Data Structures
A Walk Through - Data Structures and Algorithms
Arrays - First Step to Grouping Data
Section 2: Efficient Grouping of Data with Various Data Structures
Understanding Stacks and Queues
Maps - Working with Key-Value Pairs
Section 3: Algorithms and Efficiency
Deep-Dive into Searching Algorithms
Understanding Sorting Algorithms
Section 4: Modern and Advanced Data Structures
Collections and Data Operations in Kotlin
Introduction to Functional Programming
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Assessments

# Understanding quick sort

Like merge sort, quick sort also sorts using the principle of divide and conquer—It also takes O(n log n) to do its job, but in the extreme worst case, it can take O(n2) to sort n elements (which is very rare). We can do this in place, so the memory used in quick sort is less.

# How the quick sort algorithm works

The following gives a brief idea about how quick sort works:

1. It chooses an element called the pivot element
2. It divides the input collection into two sub-collections based on the pivot element
3. The division happens in a way that all elements in the left sub-collection are smaller than the pivot element, and all elements in the right sub-collection are larger than the pivot element
4. Now...