Introsort
Introsort (introspective sort) is a hybrid sorting algorithm that combines quicksort, heapsort, and insertion sort to achieve optimal worst-case and average-case performance. It starts with quicksort for fast average sorting, switches to heapsort when recursion depth becomes too high to avoid worst-case O(nĀ²) time, and uses insertion sort for small subarrays to improve efficiency. This makes it a robust, general-purpose sorting algorithm widely used in standard libraries like C++ STL's std::sort.
Developers should learn Introsort when implementing or optimizing sorting functions in performance-critical applications, as it guarantees O(n log n) worst-case time complexity while maintaining quicksort's speed in average cases. It is particularly useful in systems programming, data processing, and library development where reliable and efficient sorting is essential, such as in C++'s standard template library or custom sorting utilities for large datasets.