Quicksort with Python. In real life, we should always use the builtin sort provided by Python. However, understanding the quicksort algorithm is instructive. My goal here is to break down the subject such that it is easily understood and replicable by the reader without having to return to reference materials.

I had to implement the QuickSort algorithm for a homework in a language of my choice and I chose Python. During the lectures, we've been told that QuickSort is memory efficient because it works in-place; i.e., it has no additional copies of parts of the input array for recursions.

Mar 30, 2021 · You aren't doing anything with the returned values in the recursive calls quicksort(a[:index]) and quicksort(a[index+1:])-- hence those calls have no effect. You also might want to replace return a by return a[:] since your code seems to be striving to return a new, sorted array rather than an in-place sort of the given array.

Jul 26, 2021 · Another possibility is to use heapsort, which doesn't require recursion or a stack. It's also an O(n*log(n)) sort algorithm. Its average case performance is a little worse than quicksort, but it worst-case performance is still O(n*log(n)), unlike quicksort which can be worse than O(n*log(n)) in the worst case. –

Dec 19, 2012 · Early versions of Python used a hybrid of samplesort (a variant of quicksort with large sample size) and binary insertion sort as the built-in sorting algorithm. This proved to be somewhat unstable. S0, from python 2.3 onward uses adaptive mergesort algorithm. Order of mergesort (average) = O(nlogn). Order of mergesort (worst) = O(nlogn). But ...

Jun 21, 2018 · I'm trying to change this quicksort code to work with a pivot that takes a "median of three" instead. def quickSort(L, ascending = True): quicksorthelp(L, 0, len(L), ascending) def quicksorth...

Apr 8, 2019 · I am working on a homework question on creating a quick sort algorithm using a helper function called partition and using recursion. My code is raising a RecursionError, but I cannot seem to figur...

Jun 3, 2021 · I study Python alone, but I don't know this problem. What should I add? condition. Generalize and modify the quizzical alignment code so that it can be sorted by the desired criteria. The method must be handled in the same way as the key parameters utilized by the sort or min or max functions in the Python 3 standard library.

Dec 2, 2021 · I've written "maybe" quicksort algorithm, as I've noticed here the time complexity of partition was O(n) because of the for loop, Also the complexity in quicksort seems to be at least O(n). The question: how is it possible for the entire code to have total time complexity of O(nlogn).

Nov 8, 2019 · But when you are appending by iterating over all existing elements you are killing the efficiency of quicksort. Adding an element costs you O(n) and therefore splitting the list into your smaller and other list costs you already O(n^2). For (linked) lists merge sort is a much better sorting algorithm that also runs O(n*log(n)) just like quicksort.