Question

Question 4 1 pts Here is an array which has just been partitioned by the first step of quicksort: 3, 0, 2, 1, 7,. 15. 11, 20, 13 Which of these elements was the pivot? 0 7 0 1 o 20 O 15 Question 5 1 pts Running merge sort on an array of size n which is already sorted is O(n2) O O(n log n O Ollog n

Answer 1

Solution 4:

7

Explanation:

There are generally four ways of picking the pivot element in the quicksort sorting algorithm

1. Always pick first element as pivot.
2. Always pick last element as pivot
3. Pick median as pivot
4. Pick a random element as pivot.

if we choose first element then pivot would be 3 but 3 is not in options

if we choose last element then pivot would be 13 but 13 is not in options

if we choose median as pivot then 7 would be our choice and it satisfy our options

So 7 would be right answer.

Solution 5:

O(nlogn)

Because merge sort always divides the array in two parts and take linear time to merge them, so accordingly in all 3 cases (Best, Worst and Average) the time complexity will be O(nlogn).