Top MCQs on RadixSort Algorithm with Answers

Question 1

Given an array where numbers are in range from 1 to n⁶, which sorting algorithm can be used to sort these number in linear time?

• A. Not possible to sort in linear time
• B. Radix Sort
• C. Counting Sort
• D. Quick Sort

Answer: (B)

See Radix Sort for explanation.

Question 2

If we use Radix Sort to sort n integers in the range (n^k/2,n^k], for some k>0 which is independent of n, the time taken would be?

• A. Θ(n)
• B. Θ(kn)
• C. Θ(nlogn)
• D. Θ(n²)

Answer: (C)

Radix sort time complexity = O(w*n)
for n keys of word size = w 
=>w = log(n^k) 
O(w*n) = O(k*log(n).n) 
=> kO(n*log(n))

Question 3

If there are n integers to sort, each integer has d digits, and each digit is in the set {1, 2, ..., k}, radix sort can sort the numbers in:

• A. O (k (n + d))
• B. O (d (n + k))
• C. O ((n + k) lg d)
• D. O ((n + d) lg k)

Answer: (B)

If there are n integers to sort, each integer has d digits, and each digit is in the set {1, 2, ..., k}, radix sort can sort the numbers in O(d (n + k)). For more information Refer:Radix Sort Option (B) is correct.

Question 4

If there are n integers to sort, each integer has d digits and each digit is in the set {1, 2, ..., k}, radix sort can sort the numbers in :

• A. O(d n k)
• B. O(d n^k)
• C. O((d +n) k)
• D. O(d (n + k))

Answer: (D)

Question 5

The maximum number of comparisons needed to sort 9 items using radix sort is (assume each item is 5 digit octal number):

• A. 45
• B. 72
• C. 360
• D. 450

Answer: (D)