Which sorting algorithms are unstable?

What is a stable sorting algorithm?

A sorting algorithm is said to be stable if two objects with equal keys appear in the same order in sorted output as they appear in the input data set...

Do we care for simple arrays like the array of integers?

When equal elements are indistinguishable, such as with integers, or more generally, any data where the entire element is the key, stability is not an issue. Stability is also not an issue if all keys are different....

Where stable sorting algorithms are useful?

Consider the following dataset of Student Names and their respective class sections....

Which sorting algorithms are stable?

Some Sorting Algorithms are stable by nature, such as Bubble Sort, Insertion Sort, Merge Sort, Count Sort, etc. Comparison-based stable sorts such as Merge Sort and Insertion Sort maintain stability by ensuring that Element  comes before  if and only if , here i, j are indices, and . The relative order is preserved if  i.e.  comes before...

Which sorting algorithms are unstable?

Quick Sort, Heap Sort etc., can be made stable by also taking the position of the elements into consideration. This change may be done in a way that does not compromise a lot on the performance and takes some extra space, possibly ....

Can we make any sorting algorithm stable?

Any given sorting algorithm which is not stable can be modified to be stable. There can be algorithm-specific ways to make it stable, but in general, any comparison-based sorting algorithm which is not stable by nature can be modified to be stable by changing the key comparison operation so that the comparison of two keys considers position as a factor for objects with equal keys....