# LSD Radix Sort – Multiple Choice Questions and Answers (MCQs)

This set of Data Structures & Algorithms Multiple Choice Questions & Answers (MCQs) focuses on “LSD Radix Sort”.

1. LSD radix sort is faster than comparison sorts.
A) True
B) False

Explanation: When the word size is less than logn, LSD radix sort is quicker than comparison sort. For items with a larger word size and smaller radix, however, LSD radix sort takes longer.

2. Which of the following should be used to sort a huge database on a fixed-length key field?
A) Insertion sort
B) Merge sort
C) LSD radix sort
D) Quick sort

Explanation: To sort a fixed-length string, LSD radix needs only w passes, where w is the length of the strings. As a result, LSD radix sort is best for sorting a large database with a fixed-length key field.

3. Which of the following is a combination of LSD and MSD radix sorts?
A) Forward radix sort
B) 3-way radix quick sort
C) Trie base radix sort
D) Flash sort

Explanation: The advantages of LSD and MSD radix sort are combined in forward radix sort. Forward radix sort, like LSD radix sort, inspects a full horizontal strip at a time.

4. Which of the following is true for the LSD radix sort?
A) works best for variable length strings
B) accesses memory randomly
C) inner loop has less instructions
D) sorts the keys in left-to-right order

Explanation: Working with the Least Significant Digit first, the LSD radix sort sorts the keys in a right-to-left order. The inner loop contains a large number of instructions, and fixed-length strings are sorted using LSD radix sort.

5. LSD radix sort is in-place sorting algorithm.
A) False
B) True

Explanation: The LSD radix sorting algorithm is not an in-place sorting algorithm. To store the elements in the bucket, it requires additional memory, and its worst-case space complexity is O(w + R).

6. Which of the following is the distribution sort?
A) Heap sort
B) Smooth sort
C) Quick sort
D) LSD radix sort

Explanation: The input values are distributed to multiple intermediate structures in Distribution sort, which are then combined and placed on the output. LSD radix sort is a distribution sort that divides values into buckets based on the digits inside them.

7. What is the worst case time complexity of LSD radix sort?
A) O(nlogn)
B) O(wn)
C) O(n)
D) O(n + w)

Explanation: The length of time it takes to perform an LSD radix sort is determined by the word size and the number of objects. In the worst case, it takes O(wn) time, where w is the number of digits in the largest number and n is the number of inputted elements.

8. LSD radix sort requires _____ passes to sort N elements.
A) (w/logR)
B) N(w/logR)
C) (w/log(RN))
D) (wN/log(N))

Explanation: The N elements are sorted in (w/logR) passes by the LSD radix sort, where w is the number of digits in the largest number and R(radix) is the extra space needed for the sorting process.

9. Which of the following is false?
A) LSD radix sort is an integer sorting algorithm
B) LSD radix sort is a comparison sorting algorithm
C) LSD radix sort is a distribution sort
D) LSD radix sort uses bucket sort

Explanation: Bucket sort is used in LSD radix sort to group the keys based on the digits at that value. It’s an integer sorting algorithm since it groups the keys based on the digits at those values.

10. Which of the following sorting algorithm is stable?
A) Heap sort
B) Selection sort
C) In-place MSD radix sort
D) LSD radix sort

Explanation: After sorting, multiple items with the same key in LSD radix sort will be in the same order as they were in the input list. As a result, the LSD radix form is a secure sort.

Radix sort is a non-comparative sorting algorithm in computer science. By forming and distributing elements into buckets based on their radix, it prevents comparison. If an element has more than one significant digit, the bucketing process is repeated for each digit, keeping the previous step’s ordering, until all digits have been considered. As a result, radix sort is also known as bucket sort or digital sort. Radix sort can be used on any type of data that can be sorted lexicographically, including integers, terms, punch cards, playing cards, and mail. After sorting, multiple items with the same key in LSD radix sort will be in the same order as they were in the input list.