Python List Interview Questions (Top 50+)

Lists are one of the most commonly used data structures in Python. They are frequently asked in coding interviews because they test problem-solving and data manipulation skills.

In this guide, we cover essential Python list interview questions with explanations and examples.

1. Basic List Questions

Q1. What is a list in Python?

A list is an ordered, mutable collection of elements.

Q2. How to create a list?

lst = [1, 2, 3, 4]

Q3. Difference between list and tuple?

List is mutable, tuple is immutable.

Q4. How to access elements?

lst = [10, 20, 30]
print(lst[1])

2. Intermediate List Questions

Q5. Reverse a list

lst = [1,2,3]
print(lst[::-1])

Q6. Find largest element

print(max([1,2,3,4]))

Q7. Remove duplicates

lst = [1,2,2,3]
print(list(set(lst)))

Q8. Sort a list

lst = [3,1,2]
lst.sort()
print(lst)

3. Advanced List Questions

Q9. List comprehension example

squares = [x*x for x in range(5)]
print(squares)

Q10. Flatten nested list

nested = [[1,2],[3,4]]
flat = [item for sub in nested for item in sub]
print(flat)

Q11. Find second largest element

lst = list(set([1,2,3,4]))
lst.sort()
print(lst[-2])

4. Coding Problems

Problem 1: Rotate list

lst = [1,2,3,4,5]
k = 2
print(lst[-k:] + lst[:-k])

Problem 2: Count frequency

lst = [1,2,2,3]
freq = {}
for i in lst:
    freq[i] = freq.get(i,0)+1
print(freq)

Problem 3: Merge two lists

l1 = [1,2]
l2 = [3,4]
print(l1 + l2)

5. Common Mistakes

1. Confusing list and tuple.

2. Modifying list during iteration.

3. Incorrect indexing.

4. Not understanding shallow vs deep copy.

6. Interview Tips

1. Practice list problems daily.

2. Learn built-in methods like append(), extend().

3. Use list comprehensions.

4. Optimize time complexity.

7. Practice Questions

1. Find duplicates in list.

2. Remove even numbers.

3. Find intersection of lists.

4. Check if list is sorted.

5. Split list into chunks.

Conclusion

Python list questions are crucial for interviews. Mastering these concepts will improve your coding and problem-solving skills.

Practice consistently and explore advanced problems for better performance.