Table of Contents
Why quick sort is not stable?
Quick sort is not a stable algorithm because the swapping of elements is done according to pivot’s position (without considering their original positions). A sorting algorithm is said to be stable if it maintains the relative order of records in the case of equality of keys.
What is the condition for Quicksort?
It occurs when the pivot element picked is either the greatest or the smallest element. This condition leads to the case in which the pivot element lies in an extreme end of the sorted array. One sub-array is always empty and another sub-array contains n – 1 elements. Thus, quicksort is called only on this sub-array.
How do I quick sort manually?
Quick Sort Algorithm
- Step 1 – Consider the first element of the list as pivot (i.e., Element at first position in the list).
- Step 2 – Define two variables i and j.
- Step 3 – Increment i until list[i] > pivot then stop.
- Step 4 – Decrement j until list[j] < pivot then stop.
What is the minimum number of elements required for quick sort?
The base cases are subarrays of fewer than two elements, just as in merge sort. In merge sort, you never see a subarray with no elements, but you can in quicksort, if the other elements in the subarray are all less than the pivot or all greater than the pivot.
What is QuickSort worst case?
n^2
Quicksort/Worst complexity
Answer: The worst case of quicksort O(N^2) can be easily avoided with a high probability by choosing the right pivot. Obtaining an average-case behavior by choosing the right pivot element makes the performance better and as efficient as merge sort.
Why is QuickSort worst case N 2?
The worst case time complexity of a typical implementation of QuickSort is O(n2). The worst case occurs when the picked pivot is always an extreme (smallest or largest) element. This happens when input array is sorted or reverse sorted and either first or last element is picked as pivot.
Why is quicksort O N 2?