Median-of-Three Pivot
Another pivot selection strategy that helps avoid worst-case scenarios is the median-of-three pivot. Instead of selecting the pivot arbitrarily or deterministically, this method chooses the pivot as the median of three elements: the first, middle, and last elements in the subarray.
Here’s how median-of-three pivot selection works:
- Calculate the middle index of the subarray.
- Compare the values of the first, middle, and last elements.
- Select the element that falls in the middle (median) of these three values as the pivot.
The median-of-three pivot strategy ensures a more balanced partitioning because it is less likely to select an extreme element as the pivot. As a result, QuickSort is less prone to worst-case scenarios, even when dealing with partially sorted input data.
How do you avoid a worst case algorithm for a quick sort?
QuickSort is a popular and efficient sorting algorithm that relies on a divide-and-conquer strategy to sort a list of elements. It is widely used in various computer science applications due to its average-case time complexity of O(n log n), making it one of the fastest sorting algorithms available. However, QuickSort’s performance can degrade to a worst-case time complexity of O(n^2) in certain situations.