Stability of quicksort partitioning approach

Question

Does the following Quicksort partitioning algorithm result in a stable sort (i.e. does it maintain the relative position of elements with equal values):

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Answer 1

Any sort can be converted to a stable sort if you're willing to add a second key. The second key should be something that indicates the original order, such as a sequence number. In your comparison function, if the first keys are equal, use the second key.