A Level Computer Science OCR Practice Exam

Which sorting algorithm utilizes a pivot element for partitioning?

1. Insertion Sort

2. Bubble Sort

3. Quick Sort

4. Merge Sort

The correct answer is: Quick Sort

The sorting algorithm that utilizes a pivot element for partitioning is Quick Sort. This algorithm works on the principle of divide and conquer. During its execution, Quick Sort selects a pivot element from the array and rearranges the other elements into two sub-arrays according to whether they are less than or greater than the pivot. This partitioning step is crucial as it effectively divides the array into smaller sections that can then be sorted independently. Once the elements are partitioned, Quick Sort is recursively applied to the sub-arrays. This repeated division and sorting process leads to efficient sorting of the entire array. The choice of pivot is important, as a good pivot can lead to better performance, while a poor choice can degrade it to the complexity of less efficient algorithms. In contrast to Quick Sort, Insertion Sort and Bubble Sort do not use a pivot for partitioning; instead, they build the sorted array incrementally. Merge Sort, while also effective, employs a different strategy of merging sorted sub-arrays rather than using a pivot to partition elements within the array.