#### Pattern-defeating Quicksort

##### Orson R. L. Peters

A new solution for the Dutch national flag problem is proposed, requiring no three-way comparisons, which gives quicksort a proper worst-case runtime of $O(nk)$ for inputs with $k$ distinct elements. This is used together with other known and novel techniques to construct a hybrid sort that is never significantly slower than regular quicksort while speeding up drastically for many input distributions.

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