Top Interview Questions and Answers on Selection Sort

Selection sort is a simple and efficient sorting algorithm that works by repeatedly selecting the smallest (or largest) element from the unsorted portion of the list and moving it to the sorted portion of the list.

In our article “Top Interview Questions and Answers on Selection Sort”, we present a collection of questions focused on Selection Sort. These problems will help you sharpen your problem-solving skills and prepare effectively for interviews. By tackling these challenges, you can enhance your understanding of Selection Sort and boost your confidence in interviews. Let’s begin and master Selection Sort by solving Top Selection Sort Problems!

Selection Sort Interview Questions and Answers:

Question 1. What is the Selection Sort?

Answer: Selection Sort is a simple sorting algorithm that repeatedly selects the minimum (or maximum) element from the unsorted portion of the array and places it at the beginning (or end) of the sorted portion.

Question 2. Explain the algorithm of Selection Sort.

Answer: The algorithm divides the input array into two parts: the sorted and the unsorted subarray. It iterates through the unsorted subarray, finds the minimum element, and swaps it with the first element of the unsorted subarray. This process continues until the entire array is sorted.

Question 3. What is the Time and Space Complexity of Selection Sort?

Answer: The Selection sort algorithm has a time complexity of O(n²) and a space complexity of O(1) since it does not require any additional memory space apart from a temporary variable used for swapping.

Question 4. How is Selection Sort different from other sorting algorithms like Bubble Sort and Insertion Sort?

Answer: Selection Sort continuously selects the smallest (or largest) element and swaps it with the first unsorted element. Bubble Sort compares adjacent elements and swaps them if they are in the wrong order, and Insertion Sort builds the final sorted array one element at a time by repeatedly taking the next element and inserting it into the correct position.

Question 5. Can Selection Sort be considered stable or unstable?

Answer: Selection Sort is generally considered unstable because it does not preserve the relative order of equal elements.

Question 6. Is Selection Sort adaptive?

Answer: No, Selection Sort is not adaptive because it does not take into account the existing order of elements in the array.

Question 7. What happens if there are duplicate elements in the array during Selection Sort?

Answer: Selection Sort does not maintain the relative order of duplicate elements. They might get swapped during the sorting process.

Question 8. Can Selection Sort be used for large datasets?

Answer: Selection Sort is not efficient for large datasets due to its time complexity of O(n²), especially when compared to more efficient sorting algorithms like Merge Sort or Quick Sort.

Question 9. Can you optimize Selection Sort?

Answer: One optimization is to minimize the number of swaps by only swapping elements if necessary, rather than at each iteration.

Question 10. Can Selection Sort be implemented recursively?

Answer: Yes, Selection Sort can be implemented recursively, but it’s not commonly done due to the overhead of function calls and the potential risk of stack overflow for large datasets.

Question 11. Does Selection Sort work well with nearly sorted arrays?

Answer: No, Selection Sort has a fixed behavior regardless of the initial order of elements, so it does not perform particularly well with nearly sorted arrays.

Question 12. What is the best-case time complexity of Selection Sort?

Answer: The best-case time complexity of Selection Sort is Ω(N * N).

Question 13. Can Selection Sort be used for sorting linked lists?

Answer: Yes, Selection Sort can be adapted for sorting linked lists by rearranging the pointers instead of swapping elements.

Question 14. Is Selection Sort stable if implemented carefully?

Answer: It is possible to implement Selection Sort in a stable manner by modifying the swapping process to ensure that the relative order of equal elements is preserved. However, this would increase the complexity of the algorithm and might not be practical compared to other stable sorting algorithms like Merge Sort or Insertion Sort.

Question 15. Why is it called Selection Sort?

Answer: Selection Sort is so named because of the way it selects the smallest (or largest, depending on the sorting order) element from the unsorted portion of the array and swaps it with the element at the beginning of the unsorted portion. This process is repeated until the entire array is sorted.

Question 16. Is Selection Sort efficient?

Answer: Selection sort also performs well on small datasets. However, selection sort’s main limitation is its efficiency for large datasets due to its quadratic time complexity.

Question 17: What are the properties of Selection Sort?

Answer: The properties of Selection Sort are: Unstable, not adaptive, In-place, O(N*N) comparisons, O(N) swaps and O(1) extra space.

Question 18: How can Selection Sort be improved?

Answer: The Selection sort can be improved by selecting both the minimum and the maximum value simultaneously and placing them in their respective positions in a single pass. The time complexity would still be O(N*N), therefore it is not a major optimization.

Question 19: Is Selection Sort a greedy algorithm?

Answer: Yes, Selection Sort is a greedy algorithm as it takes the smallest (or largest) element in each iteration and places it at its correct position.

Question 20: How many swaps are there in Selection Sort?

Answer: In the worst case, Selection Sort makes O(N) swaps to sort the array.