A sorting algorithm is an algorithm that puts elements of a list into an order. Here are the important Questions for Interviews on Sorting Algorithms to understand, if you are going for interview where Sorting Algorithms questions will be asked then you can read these questions and get answers. Get Important Interview questions on Sorting Algorithms here…
Interview Questions on Sorting Algorithms
What is Sorting?
Sorting means arranging data in a specific order – either ascending or descending. It helps in searching faster and organizing data better.
Why is Sorting important in interviews?
Sorting is often the first step before applying other algorithms like binary search, and it’s a great way to check logic, optimization, and implementation skills.
What are the different types of Sorting Algorithms?
- Bubble Sort
- Selection Sort
- Insertion Sort
- Merge Sort
- Quick Sort
- Heap Sort
- Counting Sort
- Radix Sort
What is Bubble Sort?
It compares adjacent elements and swaps them if they’re in the wrong order. It “bubbles” the largest to the end.
Time Complexity: O(n²)
What is Selection Sort?
It selects the smallest element from the unsorted part and puts it in the correct position.
Time Complexity: O(n²)
What is Insertion Sort?
It builds the final sorted array one item at a time. Works like sorting playing cards in your hand.
Time Complexity: O(n²)
What is Merge Sort?
It divides the array into halves, sorts each half, and then merges them.
Time Complexity: O(n log n)
It’s a stable sort and great for large datasets.
What is Quick Sort?
It picks a pivot, partitions the array around the pivot, and recursively sorts.
Time Complexity: Best/Average: O(n log n), Worst: O(n²)
It’s faster than merge sort in practice but not stable.
What is Heap Sort?
It uses a binary heap data structure. It’s efficient and doesn’t need extra space.
Time Complexity: O(n log n)
What is the difference between Stable and Unstable Sorting?
Stable Sort: Keeps original order of equal elements (like Merge Sort).
Unstable Sort: Doesn’t guarantee order (like Quick Sort).
Which Sorting Algorithms are used in real life or libraries?
Python uses Timsort (a mix of Merge and Insertion Sort).
Java uses Merge Sort for objects.
C++ STL uses IntroSort (Hybrid of Quick + Heap + Insertion).
