In ECET 2026 CSE, Data Structures (DS) is a very scoring subject. Sorting algorithms are a frequent part of the exam. One of the simplest and most expected is Insertion Sort. Understanding its working and comparison count will help you solve both theory-based MCQs and coding questions.
📘 Concept Notes
🔹 Insertion Sort
- Insertion Sort builds the final sorted array one element at a time.
- Works similar to arranging playing cards in hand.
- At each step, it picks the next element and inserts it into the correct position in the already sorted part.
- Best for small data sets.
🔹 Properties
- Stable Sort: Maintains relative order of equal keys.
- In-place Algorithm: Requires only a constant amount of extra space.
- Time Complexity:
- Best Case (Already Sorted): O(n)
- Worst Case (Reverse Sorted): O(n²)
- Average Case: O(n²)
⚙️ Formulas
🔟 10 Most Expected MCQs – Insertion Sort
Q1. Insertion Sort works similar to:
A) Ticket queue
B) Arranging cards
C) Binary Search
D) Tree Traversal
Q2. Best case time complexity of Insertion Sort is:
A) O(1)
B) O(n)
C) O(n log n)
D) O(n²)
Q3. Worst case of Insertion Sort occurs when:
A) Array already sorted
B) Array reverse sorted
C) Random order
D) All equal elements
Q4. Insertion Sort is:
A) Not stable
B) Stable
C) Requires extra array
D) Uses Divide & Conquer
Q5. Number of comparisons in worst case:
A) n
B) n log n
C) n²
D) n(n-1)/2
Q6. Insertion Sort is best suited for:
A) Large datasets
B) Small datasets
C) Linked lists only
D) External sorting
Q7. Which of the following is not true about Insertion Sort?
A) Stable sort
B) In-place algorithm
C) O(n log n) in all cases
D) Works like card arrangement
Q8. Average case complexity of Insertion Sort is:
A) O(n)
B) O(n log n)
C) O(n²)
D) O(log n)
Q9. Insertion Sort is an example of:
A) Divide & Conquer
B) Incremental Approach
C) Greedy Algorithm
D) Dynamic Programming
Q10. For n=5, maximum comparisons in Insertion Sort = ?
A) 5
B) 10
C) 15
D) 20
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | B |
| Q2 | B |
| Q3 | B |
| Q4 | B |
| Q5 | D |
| Q6 | B |
| Q7 | C |
| Q8 | C |
| Q9 | B |
| Q10 | B |
🧠 Explanations
- Q1 → B: Works like arranging cards in hand.
- Q2 → B: Best case = O(n).
- Q3 → B: Reverse sorted array → Worst case.
- Q4 → B: Insertion Sort is stable.
- Q5 → D: Comparisons = n(n–1)/2.
- Q6 → B: Good for small datasets.
- Q7 → C: O(n log n) is false, Insertion Sort is O(n²).
- Q8 → C: Average case O(n²).
- Q9 → B: Insertion Sort uses incremental approach.
- Q10 → B: For n=5 → 5(5–1)/2 = 10.
🎯 Why Practice Matters
- Sorting questions are repeated every year in ECET.
- Insertion Sort is easy, yet examiners test both theory & formula-based questions.
- Understanding comparisons helps in analyzing algorithm efficiency.
💪 Motivation Talk
Don’t underestimate small topics!
Remember 👉 Big success comes from mastering small, sure-shot areas.
Practice regularly, success will follow 🚀
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