Pattern-Defeating Quicksort

Pattern-Defeating Quicksort (pdqsort) is an advanced hybrid sorting algorithm based on Quicksort that detects and defeats input patterns which would cause bad performance. It combines adaptive partitioning, branchless comparisons, and a fallback to Heapsort to guarantee O(n log n) worst-case complexity. It is used in modern standard libraries such as C++ std::sort implementations.