Engineering Questions with Answers - Multiple Choice Questions
Quicksort MCQ’s – 1
1 - Question
Which of the following sorting algorithms is the fastest?
a) Merge sort
b) Quick sort
c) Insertion sort
d) Shell sort
View Answer
Answer: b
Explanation: Quick sort is the fastest known sorting algorithm because of its highly optimized inner loop.
2 - Question
Quick sort follows Divide-and-Conquer strategy.
a) True
b) False
View Answer
Answer: a
Explanation: In quick sort, the array is divided into sub-arrays and then it is sorted (divide-and-conquer strategy).
3 - Question
What is the worst case time complexity of a quick sort algorithm?
a) O(N)
b) O(N log N)
c) O(N2)
d) O(log N)
View Answer
Answer: c
Explanation: The worst case performance of a quick sort algorithm is mathematically found to be O(N2).
4 - Question
Which of the following methods is the most effective for picking the pivot element?
a) first element
b) last element
c) median-of-three partitioning
d) random element
View Answer
Answer: c
Explanation: Median-of-three partitioning is the best method for choosing an appropriate pivot element. Picking a first, last or random element as a pivot is not much effective.
5 - Question
Find the pivot element from the given input using median-of-three partitioning method.
8, 1, 4, 9, 6, 3, 5, 2, 7, 0.
a) 8
b) 7
c) 9
d) 6
View Answer
Answer: d
Explanation: Left element=8, right element=0,
Centre=[position(left+right)/2]=6.
6 - Question
Which is the safest method to choose a pivot element?
a) choosing a random element as pivot
b) choosing the first element as pivot
c) choosing the last element as pivot
d) median-of-three partitioning method
View Answer
Answer: a
Explanation: This is the safest method to choose the pivot element since it is very unlikely that a random pivot would consistently provide a poor partition.
7 - Question
What is the average running time of a quick sort algorithm?
a) O(N2)
b) O(N)
c) O(N log N)
d) O(log N)
View Answer
Answer: c
Explanation: The best case and average case analysis of a quick sort algorithm are mathematically found to be O(N log N).
8 - Question
Which of the following sorting algorithms is used along with quick sort to sort the sub arrays?
a) Merge sort
b) Shell sort
c) Insertion sort
d) Bubble sort
View Answer
Answer: c
Explanation: Insertion sort is used along with quick sort to sort the sub arrays.
It is used only at the end.
9 - Question
Quick sort uses join operation rather than merge operation.
a) true
b) false
View Answer
Answer: a
Explanation: Quick sort uses join operation since join is a faster operation than merge.
10 - Question
How many sub arrays does the quick sort algorithm divide the entire array into?
a) one
b) two
c) three
d) four
View Answer
Answer: b
Explanation: The entire array is divided into two partitions, 1st sub array containing elements less than the pivot element and 2nd sub array containing elements greater than the pivot element.
11 - Question
Which is the worst method of choosing a pivot element?
a) first element as pivot
b) last element as pivot
c) median-of-three partitioning
d) random element as pivot
View Answer
Answer: a
Explanation: Choosing the first element as pivot is the worst method because if the input is pre-sorted or in reverse order, then the pivot provides a poor partition.
12 - Question
Which among the following is the best cut-off range to perform insertion sort within a quick sort?
a) N=0-5
b) N=5-20
c) N=20-30
d) N>30
View Answer
Answer: b
Explanation: A good cut-off range is anywhere between N=5 and N=20 to avoid nasty degenerate cases.