COP 4531: Lecture 9

Learning objectives

After this class, you should be able to:

1. Given an array A and a pivot x, show how the partitioning algorithm in the text will partition A with pivot x.
2. Given an array, show the steps taken by quicksort to sort the array.
3. Given a positive integer n, give an input of size n on which quicksort performs best.
4. Given a positive integer n, give an input of size n on which quicksort performs worst.

Reading assignment

1. CLR: Sections 7.1 - 7.2.
2. CLR: Chapter 2, section 7.3.

Exercises and review questions

• Questions on current lecture's material
  1. Show how quicksort will sort the array given in exercise 7.1-1.
  2. Exercise 7.2-1.
  3. Exercise 7.2-2.

• Questions on next lecture's material
  1. How does randomized quicksort differ from the one discussed in section 7.1?