Question

Given a list [11,5,23,45,36,99,64,4,2]. If we always select the middle element as the pivot. What is the resulting list after one round of quick partition using Hoare's method? Show steps after each swap.

Answer 1

After one round of quick partition using Hoare's method with the pivot as the middle element, the list [11, 5, 23, 45, 36, 99, 64, 4, 2] becomes [11, 5, 23, 2, 4, 99, 64, 45, 36].

Step-by-step explanation:

The question revolves around the quick sort algorithm, specifically the partitioning step using Hoare's method. The focus is on the result after one round of partitioning when always selecting the middle element as the pivot.

Here's a step-by-step breakdown:

1. Given list: [11, 5, 23, 45, 36, 99, 64, 4, 2]
2. Select the middle element as the pivot, which is 36 in this case.
3. Hoare's partitioning starts by initializing two indices - one at the start (left) and one at the end (right) of the list.
4. Move the left index to the right until an element larger than the pivot is found.
5. Move the right index to the left until an element smaller than the pivot is found.
6. Swap these two elements and continue the process until the indices cross.

The resulting list after one round of quick partition using Hoare's method is [11, 5, 23, 2, 4, 99, 64, 45, 36]. Swaps are made between elements when the left index finds a number larger than 36 and the right index finds a number smaller than 36.