#### Overview of this book

Choosing the right data structure is pivotal to optimizing the performance and scalability of applications. This new edition of Hands-On Data Structures and Algorithms with Python will expand your understanding of key structures, including stacks, queues, and lists, and also show you how to apply priority queues and heaps in applications. You’ll learn how to analyze and compare Python algorithms, and understand which algorithms should be used for a problem based on running time and computational complexity. You will also become confident organizing your code in a manageable, consistent, and scalable way, which will boost your productivity as a Python developer. By the end of this Python book, you’ll be able to manipulate the most important data structures and algorithms to more efficiently store, organize, and access data in your applications.
Preface
Free Chapter
Python Data Types and Structures
Introduction to Algorithm Design
Algorithm Design Techniques and Strategies
Stacks and Queues
Trees
Heaps and Priority Queues
Hash Tables
Graphs and Algorithms
Searching
Sorting
Selection Algorithms
String Matching Algorithms
Other Books You May Enjoy
Index

# Selection by sorting

Items in a list may undergo statistical inquiries such as finding the mean, median, and mode values. Finding the mean and mode values does not require the list to be ordered. However, to find the median in a list of numbers, the list must first be ordered. Finding the median requires you to find the element in the middle position of the ordered list. In addition, this can be used when we want to find the `k`th smallest item in the list. To find the `k`th smallest number in an unordered list of items, an obvious method is to first sort the list, and after sorting, you can rest assured that the element at index 0 will hold the smallest element in the list. Likewise, the last element in the list will hold the largest element in the list.

For more information on how to order data items within a list, see Chapter 11, Sorting. However, in order to obtain a `k`th smallest element from the list, it is not a good solution to apply a sorting algorithm to a long list of elements...