quicksort

问题 In this question: https://www.quora.com/What-is-randomized-quicksort Alejo Hausner told in: Cost of quicksort, in the worst case , that Ironically, if you apply quicksort to an array that is already sorted, you will get probably get this costly behavior I cannot get it. Can someone explain it to me. https://www.quora.com/What-will-be-the-complexity-of-quick-sort-if-array-is-already-sorted may be answer to this, but that did not get me a complete response. 回答1: The Quicksort algorithm is this:

问题 I'm writing a quicksort algorithm to sort numbers with random pivot. How can I change my quicksort methods from recursive to iterative? I have one sort method which is recursive, but I need the iterative method. Is it possible to change from recursive to iterative in just the sort method or do I have to change the whole code? here is all my code public class Main { public static void main(String[] args) { long start = System.currentTimeMillis(); ArrayList time = new ArrayList(); for (int k =

问题 I'm writing a quicksort algorithm to sort numbers with random pivot. How can I change my quicksort methods from recursive to iterative? I have one sort method which is recursive, but I need the iterative method. Is it possible to change from recursive to iterative in just the sort method or do I have to change the whole code? here is all my code public class Main { public static void main(String[] args) { long start = System.currentTimeMillis(); ArrayList time = new ArrayList(); for (int k =

问题 I recently saw Quick Sort - Computerphile video on Youtube about how quicksort works (on paper) and I have a question. Imagine that we have an array that contains for example "27,6,19,2,15,9,10" . In first place I choose 10 as pivot and the array becomes like this: 9,2,6 |10| 27,19,15 . Then I choose 6 as pivot for the left unsorted array and it becomes 2 |6| 9 and for the right one I choose 19 as a pivot and the right unsorted array becomes 15 |19| 27 . The question is: Can I choose any

问题 In attempt to learn python by practicing, I am trying to implement and test out quick sort algorithm using python. The implementation itself was not difficult, however the result of the sort is somewhat puzzling: When I sort a list ['35', '-1', '-2', '-7', '-8', '-3', '-4', '20', '-6', '53'] the result gives me ['-1', '-2', '-3', '-4', '-6', '-7', '-8', '20', '35', '53'] So the list is sorted however the negative integers are sorted in reverse order. I suspect this may be the problem with the

问题 In attempt to learn python by practicing, I am trying to implement and test out quick sort algorithm using python. The implementation itself was not difficult, however the result of the sort is somewhat puzzling: When I sort a list ['35', '-1', '-2', '-7', '-8', '-3', '-4', '20', '-6', '53'] the result gives me ['-1', '-2', '-3', '-4', '-6', '-7', '-8', '20', '35', '53'] So the list is sorted however the negative integers are sorted in reverse order. I suspect this may be the problem with the

问题 I found many implementations of quick sort algorithm, but at the end I decided to stick to this one: public static void quickSort(int array[], int start, int end) { if(end <= start || start >= end) { } else { int pivot = array[start]; int temp = 0 ; int i = start+1; for(int j = 1; j <= end; j++) { if(pivot > array[j]) { temp = array[j]; array[j] = array[i]; array[i] = temp; i++; } } array[start] = array[i-1]; array[i-1] = pivot; quickSort(array, start, i-2); quickSort(array, i, end); }} There

问题 I found many implementations of quick sort algorithm, but at the end I decided to stick to this one: public static void quickSort(int array[], int start, int end) { if(end <= start || start >= end) { } else { int pivot = array[start]; int temp = 0 ; int i = start+1; for(int j = 1; j <= end; j++) { if(pivot > array[j]) { temp = array[j]; array[j] = array[i]; array[i] = temp; i++; } } array[start] = array[i-1]; array[i-1] = pivot; quickSort(array, start, i-2); quickSort(array, i, end); }} There

问题 I am trying to make quick sort concurrent by using threading . But when i run the code with my threading approach, it only runs the same thread for all the partitions recursively. Here is what I have tried. from threading import Thread import threading import time import thread def qsort(sets,left,right): i = left j = right pivot = sets[(left + right)/2] temp = 0 while(i <= j): while(pivot > sets[i]): i = i+1 while(pivot < sets[j]): j = j-1 if(i <= j): temp = sets[i] sets[i] = sets[j] sets[j]

问题 I am trying to make quick sort concurrent by using threading . But when i run the code with my threading approach, it only runs the same thread for all the partitions recursively. Here is what I have tried. from threading import Thread import threading import time import thread def qsort(sets,left,right): i = left j = right pivot = sets[(left + right)/2] temp = 0 while(i <= j): while(pivot > sets[i]): i = i+1 while(pivot < sets[j]): j = j-1 if(i <= j): temp = sets[i] sets[i] = sets[j] sets[j]