QuickSort

Quick Sort.

A divide-and-conquer algorithm that selects a pivot element and partitions the array around it, recursively sorting each partition.

Pivot selection uses median-of-three to reduce the probability of hitting the O(n²) worst case on already-sorted or reversed input.

Time complexity : O(n log n) average, O(n²) worst case Space complexity: O(log n) stack space

The partition methods are internal so that IntroSort can reuse them directly rather than duplicating the logic.