Hunniksort

Hunniksort is a sorting algorithm that uses a binary heap to organize an unordered collection into non-decreasing order. The name, derived from the Dutch word for heap, is sometimes used in Dutch-language texts to refer to the standard, heap-based sorting method.

The typical procedure starts by transforming the input into a max-heap in place. Then, for i from n-1 down to 1, the first element (the current maximum) is swapped with the element at position i, the heap size is reduced by one, and a heapify-down operation is performed at the root to restore the heap property. After the loop completes, the array is sorted in ascending order.

In terms of complexity, hunniksort runs in O(n log n) time in the worst case: building the initial heap takes O(n) time, and each of the n−1 extractions costs O(log n). It uses O(1) auxiliary space because it sorts in place. The algorithm is not stable, meaning equal elements may not preserve their relative order.

Variants include sorting in descending order by using a min-heap or by adjusting the final output. In practice, hunniksort is essentially the in-place heapsort; implementations may differ in the heap-building step (for example, bottom-up versus alternative heapify strategies) but share the same core mechanism.

Origin and usage: the term hunnik means heap in Dutch, so hunniksort appears in some Dutch-language discussions as a direct reference to the heap-based sorting method. In broader computer science literature, the algorithm is most commonly known as heapsort, and hunniksort is not a distinct, widely recognized name.