Just wondering if someone could explain why an “unstable sort” is considered bad? Basically I don’t see any situations where it would really matter. Could anyone care to provide one?
Just wondering if someone could explain why an unstable sort is considered bad? Basically
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If you have a GUI that allows people to sort on individual columns by clicking on that column, and you use a stable sort, then people who know can get a multi-column sort on columns A,B,C by clicking on columns C,B,A in that order. Because the sort is stable, when you click on B any records with equal keys under B will still be sorted by C so after clicking on B the records are sorted by B, C. Similarly, after you click on A, the records are sorted by A, B, C.
(Unfortunately, last time I tried this on some Microsoft product or other, it looked like it didn’t use a stable sort, so it’s not surprising this trick is not better known).