Cycle Sort Interview Questions and Answers

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Cycle Sort is a comparison-based, in-place, and unstable sorting technique. We prefer to use this algorithm when the given numbers range from 1 to n. This range of questions covers the most important and popular questions of the cycle sort. The following are the most asked interview questions on the cycle sort algorithm.

There are two approaches to performing a cycle sort. Both approaches are given below:

Cycle Sort Interview Questions Approach 1

This approach is the preferable method when given numbers ranging from 1 to n; then, we are sorting elements by the use of one loop. The following are method 1 interview questions:

1. What is the method of cycle sort?

Cycle sort is the in-place sorting technique used to sort the array in one go. We use this algorithm for less usage of memory, which will be helpful in efficient sorting.

2. What is the time complexity of the cycle sort algorithm?

• Best Case: When the array is already sorted, the time complexity is O(n).
• Average Case: When each element has to move at least once per cycle, the time complexity is O(n).
• Worst Case: When the array is nearly sorted or reverse sorted, then the time complexity is O(n).

3. Why do we use cycle sort over the other sorting algorithms?

When we have less memory space to use and we have to perform the whole functionality of the algorithm in one loop, then we use a cycle sort.

4. How does cycle sort determine the correct position of each element?

Cycle sort counts how many items in the array are smaller than the current element. If 3 elements are smaller than the current element, it belongs in position 3 (using 0-based indexing).

5. Describe the basic steps of the cycle sort algorithm.

1. Select a starting element from the given list.
2. Check whether it is in the correct position or not by using the index method.
3. Swap it into the correct position with the help of the index of an array.
4. Continue this process until your first position is checked
5. Move to the next unsorted element and repeat until all elements are sorted.

6. How many swaps does a cycle sort perform in the best case?

Cycle sort takes n-1 swaps for n elements. Swapping needs each element except one needs to move exactly once.

7. Difference between cycle sort and selection sort.

The time complexity of both algorithms is slow O(n). Cycle Sort takes less memory space. Selection sort is moving everything one by one to its place, while cycle sort creates efficient chains of movements.

8. How does cycle sort perform on already sorted arrays?

When the elements are sorted, then it is the best case. It takes time complexity of O(n). It takes no additional memory writes because everything is already in place.

Cycle Sort Interview Questions Approach 2

We use this approach when numbers are given in the range of 1 to n; then, we compare each element with all other elements of an array. In this, numbers are given randomly. Method 2 explanations are given below:

1. What is the method of cycle sort?

Cycle sort is the in-place sorting technique used to sort the array by comparing two elements. If one element is more than the second, then its position will be maintained otherwise, it will be swapped. We use this algorithm for less usage of memory, which will be helpful in efficient sorting.

2. What is the time complexity of the cycle sort algorithm?

• Best Case: When the array is already sorted, the time complexity is O(n).
• Average Case: When each element has to move at least once per cycle, the time complexity is O(n).
• Worst Case: When the array is nearly sorted or reverse sorted, then the time complexity is O(n).

3. How does cycle sort determine the correct position of each element?

Cycle sort counts how many items in the array are smaller than the current element. If 3 elements are smaller than the current element, it belongs in position 3 (using 0-based indexing).

4. Describe the basic steps of the cycle sort algorithm.

• It selects the first element of an unsorted array
• It will compare this element with all other elements
• If it finds that n elements are smaller than this element, then it will place this element in the n position of the array
• It repeats this process until the whole array is sorted.

5. How many swaps does a cycle sort perform in the best case?

Cycle sort takes n-1 swaps for n elements. Swapping needs each element except one, which needs to move exactly once.

6. How does cycle sort perform on already sorted arrays?

Cycle sort takes O(n) time because it checks every element of an array. But it makes no additional memory writes because everything is already in place.

Cycle Sort Interview Questions for Both Approaches

Some questions are common in both the approaches that are given below:

1. What is the space complexity of the cycle sort algorithm?

The space complexity of the cycle sort is O(1). It takes only auxiliary space, and it is also an in-place algorithm.

2. Why is the cycle sort considered inefficient for practical use except for minimizing memory writes?

Cycle sort takes less memory, but it needs too many comparisons. For example, saving petrol but taking the longest route possible with the overall trip is still slow.

3. Why is cycle sort not a stable sorting algorithm?

Cycle Sort is not a stable algorithm because when duplicate elements appear, it changes their original order. It doesn't take care of maintaining the sequence of identical values.

4. What happens when the cycle sort encounters duplicate elements?

It places them one after another. If it sees multiple 5s, it puts them in consecutive positions after figuring out how many elements are smaller than 5.

5. What is the response of Cycle sort when an element is already in its correct position?

Firstly, we check if an element is already in its correct position before starting a new cycle. If it is, then we move to the next element without performing any writes. This type of case helps to maintain the algorithm's efficiency and minimum memory writes.

6. What is a "cycle" in a cycle sort?

A cycle is like a game of musical chairs. Element A goes to its correct spot, displacing element B, which goes to its spot, displacing element C, and so on, until an element lands in A's original position, completing the cycle.

7. What is the process of sorting in descending order?

Cycle sort will sort in descending order when we count larger elements to determine position instead of counting smaller elements.

8. What is the worst-case scenario for cycle sort in terms of writes?

If we talk about the writes, n-1 is the best case. This consistency in writing is Cycle Sort's main strength.

9. How is a cycle sort different from an insertion sort?

Insertion sort is used to sort the whole array by sorting one element at a time by repeatedly inserting and shifting elements. Cycle sort finds the exact final position of each element before placing it there.

10. Is the cycle sort adaptive or not?

Cycle sort is not adaptive because it can't work faster on partially sorted arrays and always performs the same number of comparisons.

11. What optimization can improve the cycle sort's performance?

Use binary search instead of counting one by one to find where elements belong, reducing comparison time.

12. Can we use a cycle sort with linked lists?

We can't use cycle sort with linked lists because it needs to pick an element non-contagiously around the array. Linked lists don't support quick random access like a cycle sort.