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Alan Balkany1-Apr-09 3:46
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cp98761-Apr-09 20:10
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QuestionStable Quicksort algorithm Pin
Member 419459331-Mar-09 6:04
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Lutosław31-Mar-09 12:39
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Stephen Hewitt31-Mar-09 17:11
Stephen Hewitt31-Mar-09 17:11 
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Member 41945931-Apr-09 17:16
Member 41945931-Apr-09 17:16 
Steve,

Thank you for the reference. Turns out that StableSort is a merge sort. Of course it is stable. You are always comparing elements before you select one or the other to output. My contention, having read many of the Articles on quicksort and seen their algorithms, is that they attempt to be stable once the pivot and an element is compared, but totally ignore whatever has not been seen (between i and j) when swapping i and j elements to satisfy the sort conditions i < pivot, j >= pivot. Note that you have only compared i and pivot and j and pivot, (by the algorithm, i < j), but you know nothing about what lies between i and j. Swapping these two elements may cause an unstable sort as I demonstrated in my initial post.

My attempt is to build a stable quicksort which should be faster, and not require the additional mergesort memory (see The Knuth reference, last paragraph on page 161 (Volume 3, copyright 1973). I would quote it, but cannot due to copyright restriction.

Dave.
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supercat93-Apr-09 6:22
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QuestionVector orientation Question. Pin
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QuestionHow To Scramble Numbers On These Tables? [modified] Pin
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