# Data Structure Questions and Answers-Quicksort

## Data Structure Questions and Answers-Quicksort

 Question 1
QuickSort can be categorized into which of the following?
 A Brute Force technique B Divide and conquer C Greedy algorithm D Dynamic programming
Question 1 Explanation:
First you divide(partition) the array based on the pivot element and sort accordingly.

 Question 2
Select the appropriate recursive call for QuickSort.(arr is the array, low is the starting index and high is the ending index of the array, partition returns the pivot element, we will see the code for partition very soon)
public static void quickSort(int[] arr, int low, int high)
{
int pivot;
if(high>low)
{
pivot = partition(arr, low, high);
quickSort(arr, low, pivot-1);
quickSort(arr, pivot+1, 
public static void quickSort(int[] arr, int low, int high) { int pivot; if(high
public static void quickSort(int[] arr, int low, int high) { int pivot; if(high>low) { pivot = partition(arr, low, high); quickSort(arr, low, pivot); quickSort(arr, pivot, high); } }class="hk1....style-wrap2">
public static void quickSort(int[] arr, int low, int high) { 	int pivot; 	if(high>low) 	{ 		pivot = partition(arr, low, highUPSC test Questions answers Question 2 Explanation:   Based on the pivot returned by the call to partition, recursive calls to quickSort sort the given array.
 Question 3
What is the worst case complexity of QuickSort?
 A O(nlogn) B O(logn) C O(n) D O(n2)
Question 3 Explanation:
When the input array is already sorted.

 Question 4
What is a randomized QuickSort?
 A The leftmost element is chosen as the pivot B The rightmost element is chosen as the pivot C Any element in the array is chosen as the pivot D A random number is generated which is used as the pivot
Question 4 Explanation:
QuickSort is randomized by placing the input data in the randomized fashion in the array or by choosing a random element in the array as a pivot.

 Question 5
Which of the following code performs the partition operation in QuickSort?
 A private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left >  B private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while C private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left <= ri D private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left > rig