Introsort or introspective sort is a hybrid sorting algorithm that provides both fast average performance and (asymptotically) optimal worst-case performance. It begins with quicksort, it switches to heapsort when the recursion depth exceeds a level based on (the logarithm of) the number of elements being sorted and it switches to insertion sort when the number of elements is below some threshold. This combines the good parts of the three algorithms, with practical performance comparable to quicksort on typical data sets and worst-case O(n log n) runtime due to the heap sort. Since the three algorithms it uses are comparison sorts, it is also a comparison sort.
Introsort was invented by David Musser in Musser (1997), in which he also introduced introselect, a hybrid selection algorithm based on quickselect (a variant of quicksort), which falls back to median of medians and thus provides worst-case linear complexity, which is optimal. Both algorithms were introduced with the purpose of providing generic algorithms for the C++ Standard Library which had both fast average performance and optimal worst-case performance, thus allowing the performance requirements to be tightened.[1] Introsort is in-place and a non-stable algorithm.
Introsort or introspective sort is a hybrid sorting algorithm that provides both fast average performance and (asymptotically) optimal worst-case performance...
performance and optimal worst-case performance. Introselect is related to the introsort sorting algorithm: these are analogous refinements of the basic quickselect...
insertion sort, and additional logic), used in Android, Java, and Python, and introsort (quicksort and heapsort), used (in variant forms) in some C++ sort implementations...
required to avoid bad pivot choices and the resultant O(n2) performance. Introsort is a variant of quicksort which solves this problem by switching to heapsort...
Library (STL). In Musser (1997), he developed the sorting algorithm called introsort (also known as introspective sort), and the related selection algorithm...
complexity. Heapsort, O ( n log n ) {\displaystyle O(n\log n)} , merge sort, introsort, binary tree sort, smoothsort, patience sorting, etc. in the worst case...
complexity. Another example of hybrid algorithms for performance reasons are introsort and introselect, which combine one algorithm for fast average performance...
makes their implementation far more complex, and implementations such as introsort and pattern-defeating quicksort use heapsort as a last-resort fallback...
Humorous or ineffective Bogosort Slowsort Stooge sort Hybrid Flashsort Introsort: begin with quicksort and switch to heapsort when the recursion depth...
performance of spreadsort is O(n log n) for small data sets, as it uses introsort as a fallback. In the case of distributions where the size of the key...
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