What kind of coding questions are asked in an interview?

In coding interviews, questions typically test your problem-solving skills, understanding of algorithms, and knowledge of data structures. Here’s an overview of the common types of coding questions you might encounter:

1. Array and String Manipulation

Examples

• Find the missing number in an array of integers.
• Check if two strings are anagrams.
• Rotate an array by k positions.

Why They’re Asked

To test your ability to manipulate data and work with fundamental structures.

2. Sorting and Searching Algorithms

Examples

• Implement quicksort or mergesort.
• Search for a target element in a rotated sorted array.
• Find the first and last position of a target in a sorted array (binary search).

Why They’re Asked

To evaluate your understanding of efficiency and algorithmic thinking.

3. Dynamic Programming

Examples

• Solve the knapsack problem.
• Find the longest increasing subsequence.
• Compute the minimum cost path in a grid.

Why They’re Asked

To test your ability to break down complex problems and optimize solutions.

4. Linked Lists

Examples

• Detect a cycle in a linked list.
• Merge two sorted linked lists.
• Reverse a linked list.

Why They’re Asked

To assess your understanding of pointer manipulation and memory handling.

5. Trees and Graphs

Examples

• Traverse a binary tree (in-order, pre-order, post-order).
• Find the shortest path in a graph (e.g., Dijkstra's algorithm).
• Check if a binary tree is balanced.

Why They’re Asked

To evaluate your knowledge of hierarchical and connected data structures.

6. Recursion and Backtracking

Examples

• Solve a Sudoku puzzle.
• Generate all permutations of a string.
• N-Queens problem.

Why They’re Asked

To test your ability to think recursively and explore solutions.

7. Hashing

Examples

• Find the first non-repeating character in a string.
• Count the number of subarrays with a given sum.
• Check for duplicates in an array.

Why They’re Asked

To test your ability to use hash maps for efficient data retrieval.

8. Stack and Queue Problems

Examples

• Implement a stack using queues.
• Evaluate a postfix expression.
• Find the maximum in a sliding window.

Why They’re Asked

To test your understanding of linear data structures and their applications.

9. System Design and Scalability

Examples

• Design a URL shortening service.
• Implement a rate limiter.
• Design a messaging queue system.

Why They’re Asked

To assess your ability to handle real-world scalability challenges.

10. Big-O Complexity Analysis

Examples

• Analyze the time complexity of an algorithm.
• Optimize an inefficient function.

Why They’re Asked

To evaluate your understanding of algorithmic efficiency and trade-offs.

Suggested Resources

• Grokking the Coding Interview: Patterns for Coding Questions
  Focuses on identifying patterns to tackle similar problems efficiently.
  Check it out here

• Grokking Advanced Coding Patterns for Interviews
  Ideal for mastering advanced patterns often asked in interviews.
  Check it out here

• Grokking Algorithm Complexity and Big-O
  Perfect for understanding complexity and optimizing solutions.
  Check it out here

With thorough preparation and consistent practice, you’ll develop the skills needed to excel in coding interviews.