Top 9 Coding Interview Questions With Answers

Coding interviews are specialised types of interviews that are given by candidates who specialise in the field of computer science and software engineering. These interviews test a candidate’s arithmetic and computer programming problems which are essential for coding and problem-solving tasks. With this type of self-introduction or interview, candidates’ coding style, technical proficiency, how creatively they can solve problems, etc. are measured. However, the objective of the coding interview questions is not only to determine an applicant’s abilities to solve problems but also to gauge their coding practices, adaptability and ability to work under pressure. These questions generally start with, ‘How did you develop an interest in coding,’ ‘What type of coding you are skilled in,’ ‘Where did you learn coding,’ etc. 

In this article, we will cover some of the most common interview questions with their answers.

Also Read: Coding for Beginners: A Step-by-Step Guide

Tips to Answer Coding Interview Questions

Coding interviews are as much about problem-solving skills as they are about coding ability. Practice and preparation will boost your confidence and performance. Here are six tips to help you excel in coding interviews:

• Regular coding practice is essential. Solve a variety of problems to build your problem-solving skills and familiarity with different algorithms and data structures.
• Deeply understand the basics of algorithms, data structures, and time/space complexity. This foundation will help you approach complex problems more effectively.
• Break down the problem into smaller subproblems. Tackle each subproblem individually, then combine solutions to solve the main problem.
• Explain your thought process as you work through the problem. Interviewers value your reasoning and approach more than just the final solution.
• Test your code with sample inputs and edge cases. Once it works, consider optimizing it by reducing time complexity or improving code readability.
• Whether you solve the problem or not, communicate your thought process clearly. Even if you are stuck, sharing your approach might earn you partial credit.

Also Read: Handle Tough Interview Questions With Ease

Most Common Coding Interview Questions

Candidates appearing or preparing for a coding interview must keep themselves updated about the recent developments taking place in the field of coding as the interviewer might start the interview by asking ‘What are your views on the latest developments in coding?’ Or the interview might present a problem to you when your coding skills are required to solve it. 

Sometimes appearing for an interview where you are required to highlight your personal opinions and technical skills at the same time can be arduous. But as they say, every problem has a solution at its own level, and so does a job interview or coding interview. Below we have divided the coding interview questions into two categories: Conceptual and Programming Questions. Below we have discussed the conceptual interview questions asked to a developer in a job interview.

Define data structure

Answer: “A data structure is a collection of information stored in a computer’s memory or storage system to facilitate various operations and manipulation of that data. It defines how data is organised, accessed and managed and the relationships and operations that can be performed using that specific data.”

What is a Stack?

Answer: “A stack is a collection of various elements with two primary operations: Push and Pop. Push operations add an element to the top and pop operations remove the top element. Stacks perform operations on a LIFO basis, which stands for Last-In-First-Out.”

Also Read: Top 10 Questions Asked in a Full-Stack Developer Interview

What is a FIFO?

Answer one of the most important coding interview questions with ‘The concept of FIFO, which stands for First-In-First-Out, is commonly used in computing, especially in data structures and scheduling algorithms. FIFO is a principle that dictates that the first element added to a system should be the first one to be removed or processed. Through this, items are processed in the order in which they were added.”

What is a LIFO?

Answer: “LIFO is a concept used in computer programming, data structuring and memory management. It stands for Last-In-First-Out, and in this, the last system is added or pushed into a collection in the first one and the first one added is removed from the collection. LIFO is the opposite of FIFO.”

Also Read: Self Introduction for Full Stack Developer

Explain the difference between an array and a linked list. When would you choose one over the other?

Answer one of this most common coding interview questions like: “Arrays and linked lists are both fundamental data structures that are used for storing the collection of elements, but there are differences in their characteristics and uses. An array is a contiguous memory block that stores elements of the same data type. On the other hand, a linked list is made of nodes, each containing an element and a reference to the next element in the list. Elements in an array are accessed using an index and provide direct and consent-time access to any element. Linked lists allow dynamic resizing since the addition or deletion of nodes can be done to relocate the entire structure.”

What are Binary Trees?

Binary trees in coding are used for various tasks such as implementing algorithms, organising data efficiently and solving problems. The commonly used application of binary trees in coding is implementing binary research trees. Binary research trees provide efficient searching, insertion and deletion operations.

Also Read: 40+ Data Science Interview Questions and How to Answer

What is a Queue?

Queues are known as linear data structures where operations are performed in the order of FIFO. In a queue, the elements added earlier are removed before those that were added later and are opposed to a stack.

What is the purpose of exception handling in programming? How does it help in managing errors and maintaining program stability?

Exception handling is a programming technique providing structured ways to deal with runtime errors and other exception handling that can occur during the execution of programs. With this, programmers can handle unexpected scenarios in a controlled and graceful manner, preventing the program from crashing and providing a way to recover or any other alternative behaviour.

Also Read: Self Introduction for Computer Science Student

Define the SOLID principles in object-oriented design.

The SOLID principles are 5 different design principles for writing maintainable and scalable software in object-oriented programming. Introduced by Robert C. Martin, these principles provide guidelines for creating flexible, understandable and maintainable codebase. In SOLID, S stands for Single Responsibility Principle (SRP), O for Open/Closed Principle (OCP), L for Liskov Substitution Principle (LSP), I for Interface Segregation Principle (ISP) and D for Dependency Inversion Principle (DIP).

Also read – How to Crack a Personal Interview?

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