quicksort Questions

2

I'm doing an analysis for the quicksort (qsort from c++ STL) algorithm, the code is: #include <iostream> #include <fstream> #include <ctime> #include <bits/stdc++.h> #includ...
Sandrasandro asked 16/3, 2021 at 17:34

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In QuickSort, a lot of time is spent on the swap temp:=var[i]; var[i]:=var[j]; var[j]:=temp. When the vars are integer I time 140 msec for a large random array. When the vars are string, the time i...
Ulcerate asked 9/1, 2021 at 22:8

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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?
Inappreciative asked 5/12, 2009 at 19:38

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I have come across this question: Let 0<α<.5 be some constant (independent of the input array length n). Recall the Partition subroutine employed by the QuickSort algorithm, as explained in...
Alcides asked 25/8, 2014 at 0:53

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Haskell's website introduces a very attractive 5-line quicksort function, as seen below. quicksort [] = [] quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater) where lesser = filt...
Rube asked 10/10, 2011 at 19:32

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From what I understood in Wikipedia's explanation of quicksort's space complexity, quicksort's space complexity comes from its recursive nature. I'm curious as to whether it's possible to implement...
Ascendancy asked 12/7, 2012 at 15:27

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How can I implement a concurrent quicksort or mergesort algorithm for Java? We've had issues on a 16-(virtual)-cores Mac where only one core (!) was working using the default Java sorting algo and...
Misdeem asked 5/2, 2010 at 20:27

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I am comparing the performance between Julia and C++. Then I found quick sort is much faster in Julia (and even faster than C++), especially when the size of array is very big. Can anyone explain t...
Normalie asked 15/7, 2020 at 15:10

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I found quicksort algorithm from this book This is the algorithm QUICKSORT (A, p, r) if p < r q = PARTITION(A, p, r) QUICKSORT(A, p, q-1) QUICKSORT(A, q+1, r) PARTITION(A, p, r) x=A[r] i...
Counterclaim asked 30/11, 2012 at 15:34

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Sort the following array a using quicksort, [6, 11, 4, 9, 8, 2, 5, 8, 13, 7] The pivot should be chosen as the arithmetic mean of the first and the last element, i.e., (a[0] + a[size - 1]) / 2 (...
Cornwallis asked 24/5, 2011 at 14:8

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I was asked this question during an interview. They're both O(nlogn) and yet most people use Quicksort instead of Mergesort. Why is that?
Tradeswoman asked 16/9, 2008 at 8:37

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I tried to search on Web and in my algorithms book if the Lomuto's specific solution of QSort Partition is stable or not (I know that the Hoare's version is unstable) but i didn't find a precise an...
Kaz asked 10/7, 2011 at 12:30

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What is QuickSort with a 3-way partition?
Uneven asked 2/6, 2009 at 19:27

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Here is a quicksort algorithm for numbers written in Clojure. It is basically the quicksort algorithm found in "The Joy of Clojure", 2nd edition, page 133. I modified it slightly for (hopefully) be...
Sanskritic asked 16/7, 2019 at 8:55

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I've never seen dual pivot quick sort before. Is it an upgraded edition of quick sort? And what is the difference between dual pivot quick sort and quick sort?
Melamie asked 4/1, 2014 at 6:6

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I have got this seemingly trivial parallel quicksort implementation, the code is as follows: import System.Random import Control.Parallel import Data.List quicksort :: Ord a => [a] -> [a] q...
Confessional asked 3/11, 2013 at 12:32

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I have an algorithm for parallel sorting a list of a given length: import Control.Parallel (par, pseq) import Data.Time.Clock (diffUTCTime, getCurrentTime) import System.Environment (getArgs) impo...
Rampageous asked 23/4, 2019 at 12:0

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What is the median of three strategy to select the pivot value in quick sort? I am reading it on the web, but I couldn't figure it out what exactly it is? And also how it is better than the random...
Moulmein asked 26/9, 2011 at 18:34

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Java 6's Arrays.sort method uses Quicksort for arrays of primitives and merge sort for arrays of objects. I believe that most of time Quicksort is faster than merge sort and costs less memory. My e...
Gandhi asked 14/9, 2010 at 8:23

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Quicksort is not stable, since it exchanges nonadjacent elements. Please help me understanding this statement. I know how partitioning works, and what stability is. But I cant figure out what ...
Contorted asked 21/11, 2012 at 16:56

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A sorting algorithm is stable if it preserves the relative order of any two elements with equals keys. Under which conditions is quicksort stable? Quicksort is stable when no item is passed unless...
Maintenon asked 27/4, 2011 at 12:29

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Isn't Insertion sort O(n^2) > Quicksort O(n log n)...so for a small n, won't the relation be the same?
Pt asked 12/11, 2011 at 0:35

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I'm working on the program just needed in the following to understand it better. What is the worst case running time for Quicksort and what may cause this worse case performance? How can we modify...
Interplanetary asked 25/10, 2010 at 22:56

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I recently read about quicksort and was wondering whether it would be smart to build my own function to sort things with quicksort or if it would be inefficent. What do you think is the built in so...
Hyaloid asked 13/6, 2009 at 8:22

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I implemented the QuickSort-Algorithm 3 times and measured the time for sorting 50 million random numbers: sequential (took ~14 seconds) With Parallel.Invoke() in the same method as the sorting a...
Galore asked 13/4, 2018 at 13:20

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