🔥 Searching Algorithms — Interview Questions with Answers 🔍💻

1️⃣ What is Linear Search?

Linear Search is a method where you check each element one by one until the target is found.

Example:
Find 5 in [2, 4, 5, 9]
→ check 2 → check 4 → check 5 ✅

It works on unsorted data, but is slower for large datasets.

2️⃣ What is Binary Search?

Binary Search is a technique where you divide the sorted array into halves to find the target efficiently.

Example:
Find 7 in [2, 4, 7, 10]
→ middle = 7 → found

It is much faster but requires sorted data.

3️⃣ What is the main difference between Linear Search and Binary Search?

Linear Search checks elements one by one, while Binary Search repeatedly divides the search space into halves.

Example:

• Linear → may check all elements
• Binary → reduces search area quickly

So Binary Search is faster for large datasets.

4️⃣ What is the time complexity of Linear Search?

Worst case: O(n)

Example:
If element is at the end or not present, all elements are checked.

5️⃣ What is the time complexity of Binary Search?

O(log n)

Example:
For 1000 elements:

• Linear → up to 1000 checks
• Binary → around 10 checks

6️⃣ Why does Binary Search require sorted data?

Because it relies on comparing the middle element to decide whether to search left or right.

If data is unsorted, this logic breaks.

Example:
Unsorted → [7, 2, 10, 4] → cannot decide direction correctly.

7️⃣ What are the common mistakes in Binary Search?

• Using it on unsorted data
• Incorrect calculation of middle index
• Infinite loops due to wrong conditions
• Not handling edge cases

8️⃣ What is the space complexity of Binary Search?

• Iterative version → O(1)
• Recursive version → O(log n) due to call stack

9️⃣ When should you prefer Linear Search?

• When data is unsorted
• When dataset is small
• When simplicity is preferred

🔟 When should you prefer Binary Search?

• When data is sorted
• When dataset is large
• When performance matters

⭐ Bonus Interview Question

Q: Can Binary Search be used on linked lists?

Not efficiently, because linked lists do not support direct access to the middle element.
Binary Search works best with arrays.

🎯 Interview Tip

Always mention:
• Time complexity
• Condition (sorted or not)
• Why you chose that approach

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