💻 Coding Interview Questions

1️⃣ What is an algorithm?
Answer: A step-by-step procedure to solve a problem.

2️⃣ What is Big-O notation?
Answer: It describes the worst-case time or space complexity of an algorithm.

3️⃣ What is a binary search?
Answer: A search algorithm that repeatedly divides a sorted array in half.

4️⃣ Linear search vs Binary search?
Answer: Linear search checks every element; binary search divides the search space (needs sorted data).

5️⃣ What is a function?
Answer: A reusable block of code that performs a specific task.

6️⃣ What is a compiler?
Answer: A program that translates source code into machine code.

7️⃣ What is an interpreter?
Answer: A program that executes code line by line.

8️⃣ What is a runtime error?
Answer: An error that occurs while the program is running.

9️⃣ What is memory leak?
Answer: When a program uses memory but fails to release it.

🔟 What is an exception?
Answer: An error that disrupts normal program execution and can be handled.

💻 Coding Interview Questions

1️⃣ What is an object?
Answer: An instance of a class containing data and methods.

2️⃣ What is a class?
Answer: A blueprint used to create objects.

3️⃣ What is OOP?
Answer: Object-Oriented Programming; it organizes code using objects and classes.

4️⃣ Name the four pillars of OOP.
Answer: Encapsulation, Inheritance, Polymorphism, Abstraction.

5️⃣ What is encapsulation?
Answer: Binding data and methods together and restricting direct access.

6️⃣ What is inheritance?
Answer: When a class derives properties and methods from another class.

7️⃣ What is polymorphism?
Answer: One interface, multiple implementations.

8️⃣ What is abstraction?
Answer: Hiding implementation details and showing only essentials.

9️⃣ What is an interface?
Answer: A contract that defines methods without implementation.

🔟 What is method overloading?
Answer: Multiple methods with the same name but different parameters.

PostgreSQL Architecture

💻 Coding Interview Questions

1️⃣ What is a database?
Answer: An organized collection of data for efficient storage and retrieval.

2️⃣ What is SQL?
Answer: Structured Query Language used to manage relational databases.

3️⃣ What is a primary key?
Answer: A unique identifier for each record in a table.

4️⃣ What is a foreign key?
Answer: A key that links one table to another.

5️⃣ What is normalization?
Answer: Organizing data to reduce redundancy.

6️⃣ What is an index in a database?
Answer: A structure that improves data retrieval speed.

7️⃣ What is a JOIN?
Answer: Combines rows from multiple tables based on a condition.

8️⃣ INNER JOIN vs LEFT JOIN?
Answer: INNER returns matching rows; LEFT returns all left-table rows.

9️⃣ What is ACID?
Answer: Atomicity, Consistency, Isolation, Durability.

🔟 What is a transaction?
Answer: A sequence of database operations executed as a single unit.

Program vs Process vs Thread

The “I’ve Never Seen This Before” Moment

🗯Scenario: The interviewer finishes explaining the problem and you realize you have never practiced anything like it.

👉 Do this: Shift into discovery mode. Ask about constraints, input size, and edge cases. Then propose a naive solution first and improve it. This shows structured thinking and calm problem solving, which often scores higher than instantly jumping to an optimal answer.

❔Interviewer:

Explain the difference between horizontal and vertical scaling.

✅ Answer:

Vertical scaling means increasing the resources of a single machine, such as adding more CPU or memory. It is simpler to implement but has hardware limits and can become a single point of failure.

Horizontal scaling means adding more machines and distributing the load across them. It provides better fault tolerance and scalability but introduces additional complexity such as load balancing, data consistency, and distributed coordination.

Modern high scale systems typically favor horizontal scaling because it supports elastic growth and higher availability.

The Memory Usage Question

🗯 Scenario: After solving the problem, the interviewer asks about space complexity and you did not track it.

👉 Do this: Always mention both time and space when presenting a solution. Count auxiliary data structures and recursion stack if present. Technically, many candidates forget that recursion adds implicit space. Calling this out makes you look much more thorough.

💻 Coding Interview Questions

1️⃣ What is a pointer?
Answer: A variable that stores the memory address of another variable.

2️⃣ What is memory allocation?
Answer: The process of reserving memory for program execution.

3️⃣ Stack vs Heap memory?
Answer: Stack is fast and automatic; heap is dynamic and manually managed.

4️⃣ What is garbage collection?
Answer: Automatic memory cleanup of unused objects.

5️⃣ What is a deadlock?
Answer: When processes wait forever for resources held by each other.

6️⃣ What is multithreading?
Answer: Running multiple threads concurrently within a process.

7️⃣ What is synchronization?
Answer: Controlling access to shared resources in concurrent programs.

8️⃣ What is a race condition?
Answer: When multiple threads access shared data unsafely.

9️⃣ What is a process?
Answer: An independent program in execution.

🔟 What is a thread?
Answer: The smallest unit of execution within a process.

The Final Question Trap

🗯 Scenario: The interviewer smiles and says,

Do you have any questions for us?

👉 Do this: Always have one thoughtful question ready. Ask about the team’s biggest technical challenge or what success looks like in the first six months. Sharp questions make you memorable long after the coding part ends.