heapsort

Why not use heap sort always [duplicate]

天大地大妈咪最大 提交于 2019-11-28 03:05:43
This question already has an answer here: Quicksort vs heapsort 11 answers Quicksort superiority over Heap Sort 5 answers The Heap Sort sorting algorithm seems to have a worst case complexity of O(nlogn), and uses O(1) space for the sorting operation. This seems better than most sorting algorithms. Then, why wouldn't one use Heap Sort always as a sorting algorithm (and why do folks use sorting mechanisms like Merge sort or Quick sort)? Also, I have seen people use the term 'instability' with Heap sort. What does that imply? A stable sort maintains the relative order of items that have the same

Quicksort vs heapsort

谁说胖子不能爱 提交于 2019-11-27 02:39:43
Both quicksort and heapsort do in-place sorting. Which is better? What are the applications and cases in which either is preferred? DVK This paper has some analysis. Also, from Wikipedia: The most direct competitor of quicksort is heapsort. Heapsort is typically somewhat slower than quicksort, but the worst-case running time is always Θ(nlogn). Quicksort is usually faster, though there remains the chance of worst case performance except in the introsort variant, which switches to heapsort when a bad case is detected. If it is known in advance that heapsort is going to be necessary, using it

Lower bound on heapsort?

旧巷老猫 提交于 2019-11-27 01:38:14
问题 It's well-known that the worst-case runtime for heapsort is Ω(n lg n), but I'm having trouble seeing why this is. In particular, the first step of heapsort (making a max-heap) takes time Θ(n). This is then followed by n heap deletions. I understand why each heap deletion takes time O(lg n); rebalancing the heap involves a bubble-down operation that takes time O(h) in the height of the heap, and h = O(lg n). However, what I don't see is why this second step should take Ω(n lg n). It seems like

Quicksort superiority over Heap Sort

时光怂恿深爱的人放手 提交于 2019-11-27 00:27:30
Heap Sort has a worst case complexity of O(nlogn) while Quicksort has O(n^2) . But emperical evidences say quicksort is superior. Why is that? One of the major factors is that quicksort has better locality of reference -- the next thing to be accessed is usually close in memory to the thing you just looked at. By contrast, heapsort jumps around significantly more. Since things that are close together will likely be cached together, quicksort tends to be faster. However, quicksort's worst-case performance is significantly worse than heapsort's is. Because some critical applications will require

Why not use heap sort always [duplicate]

元气小坏坏 提交于 2019-11-26 23:55:52
问题 This question already has answers here : Quicksort vs heapsort (11 answers) Quicksort superiority over Heap Sort (5 answers) Closed 5 years ago . The Heap Sort sorting algorithm seems to have a worst case complexity of O(nlogn), and uses O(1) space for the sorting operation. This seems better than most sorting algorithms. Then, why wouldn't one use Heap Sort always as a sorting algorithm (and why do folks use sorting mechanisms like Merge sort or Quick sort)? Also, I have seen people use the