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## Data Structure Questions and Answers-Quicksort

Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

QuickSort can be categorized into which of the following?

Brute Force technique | |

Divide and conquer | |

Greedy algorithm | |

Dynamic programming |

Question 1 Explanation:

First you divide(partition) the array based on the pivot element and sort accordingly.

Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

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, high |

What is the worst case complexity of QuickSort?

O(nlogn) | |

O(logn) | |

O(n) | |

O(n ^{2}) |

Question 3 Explanation:

When the input array is already sorted.

Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

What is a randomized QuickSort?

The leftmost element is chosen as the pivot | |

The rightmost element is chosen as the pivot | |

Any element in the array is chosen as the pivot | |

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 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

Which of the following code performs the partition operation in QuickSort?

private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left > | |

private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while | |

private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left <= ri | |

private static int partition(int[] arr, int low, int high) { int left, right, pivot....item = arr[low]; left = low; right = high; while(left > rig |

Question 5 Explanation:

The array is partitioned such that the elements left to the pivot are lesser than the pivot while the elements right of the pivot are greater than the pivot.

There are 5 questions to complete.