2012年5月3日 · More recently other modifications to Quicksort have been invented (e.g., Introsort, PDQ Sort) which prevent that O(N 2) worst case. Introsort does so by keeping track of the current partitioning "level", and when/if it goes too deep, it'll switch to a heap sort, which is slower than Quicksort for typical inputs, but guarantees O(N log N ...

2017年7月26日 · By definition a sort is stable if, after the sort, the two elements that compare as if equal (the two 4s) appear in the same order afterwards as they did before. Suppose we choose 3 as the pivot. The two 4 elements will end up after it and the 1 and the 2 before it (there's a bit more to it than that, I've ignored moving the pivot since it's ...

2008年9月16日 · Quick sort is an in-place sorting algorithm, so its better suited for arrays. Merge sort on the other hand requires extra storage of O(N), and is more suitable for linked lists. Unlike arrays, in liked list we can insert items in the middle with O(1) space and O(1) time, therefore the merge operation in merge sort can be implemented without any ...

2011年4月26日 · C++ quick sort algorithm. Ask Question Asked 13 years, 9 months ago. Modified 11 months ago. Viewed 16k ...

This is the shortest implementation of Quick Sort algorithm (Without StackOverflowException)

Deterministic quicksort algorithms usually have the drawback that either (1) they run in worst-case time O(n log n), but with a high constant factor, or (2) they run in worst-case time O(n 2) and the sort of input that triggers this case is deterministic.

2016年9月23日 · The execution speed of the algorithm depends largely on how this mechanism is implemented, poor implementation can assume that the algorithm is run at a slow speed. The choice of pivot determines partitions the data list, therefore, this is the most critical part of the implementation of the Quicksort algorithm.

2012年9月17日 · Sure: for n items, the work done by quicksort is A.n.log(n) (in the expected case) while the work done by insertion sort is B.n^2, where A and B are the constant factors corresponding roughly to "cost of instructions executed per iteration".

To get the "full effect" of the median of three, it's also important to sort those three items, not just use the median as the pivot -- this doesn't affect what's chosen as the pivot in the current iteration, but can/will affect what's used as the pivot in the next recursive call, which helps to limit the bad behavior for a few initial ...

2019年3月19日 · Btw Wikipedia says: Quicksort (also known as "partition-exchange sort") is a comparison sort and, in efficient implementations, is not a stable sort. (edit: just saw that you also commented this on the OP's question ;)) –