19 questions · from 2 interviews
Pubmatic interview questions
Every question candidates reported from their Pubmatic interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Pubmatic coding and DSA questions
- 01
Rotate Array at Index k
Given an array, rotate the array to the right by k steps, where k is non-negative. For example, if array is [1,2,3,4,5,6,7] and k=3 , the output should be [5,6,7,1,2,3,4] .
Easy · From Pubmatic Java Developer Interview Experience | Pune
- 02
Detect Cycle in Linked List
Given the head of a singly linked list, determine if it has a cycle in it. There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the next pointer.
Easy · From Pubmatic Java Developer Interview Experience | Pune
- 03
Tic Tac Toe Winner NxN Board
Given a completed Tic Tac Toe board of size NxN, determine if there is a winner. A winner is defined as N consecutive marks (either 'X' or 'O') in any row, column, or diagonal.
Medium · From Pubmatic Java Developer Interview Experience | Pune
- 04
Depth-First Search (DFS) Implementation
Provide pseudocode or a high-level explanation for implementing the Depth-First Search (DFS) algorithm for traversing a graph or tree. Discuss its typical applications.
Easy · From Pubmatic Java Developer Interview Experience | Pune
- 05
Implement Pascal's Triangle
Implement a function to generate Pascal's triangle up to a given number of rows.
Easy · From PubMatic | Intern+FTE | Pune | April 2022
- 06
Frequency Sort Billions of Names (Without STL)
Given an incoming stream or list containing billions of names, determine the frequency of each name and then sort the names in ascending order based on their frequencies. The use of Standard Template Library (STL) is not permitted. This question involved OOPS…
Hard · From PubMatic | Intern+FTE | Pune | April 2022
Pubmatic system design questions
- 01
Scale Project to Million Users
Discuss strategies and architectural considerations for scaling a web application or project to effectively handle a workload of a million concurrent users. Cover aspects like load balancing, database scaling, caching, microservices, etc.
- 02
Low-Level Design (LLD) for Snake and Ladder Game
Design the core components and interactions for a Snake and Ladder game. This includes designing classes for Player, Board, Dice, Snake, Ladder, and the Game itself, along with their attributes and methods.
Medium · From Pubmatic Java Developer Interview Experience | Pune
- 03
Scale System to Million Users (Round 3)
Discuss strategies and architectural considerations for scaling a web application or project to effectively handle a workload of a million concurrent users. Cover aspects like load balancing, database scaling, caching, microservices, etc. (Asked again in a…
Pubmatic other questions
- 01
Explain Spring MVC Architecture
Describe the architecture of the Spring Model-View-Controller (MVC) framework, including its core components like DispatcherServlet, Controller, Model, View, and View Resolver, and how they interact to handle a web request.
- 02
Java Streams Concepts
Explain the concept of Java Streams API introduced in Java 8. Discuss its features, common operations (filter, map, reduce), intermediate and terminal operations, and benefits over traditional collections processing.
- 03
Object-Oriented Programming (OOPS) Concepts
Explain the fundamental principles of Object-Oriented Programming (OOPS): Encapsulation, Inheritance, Polymorphism, and Abstraction. Provide real-world examples or code snippets to illustrate each concept.
- 04
Database Indexing
Explain what database indexing is, why it's used, and how it improves query performance. Discuss different types of indexes (e.g., clustered vs. non-clustered) and their trade-offs.
- 05
Multithreading and Race Conditions
Explain multithreading in Java, including how threads are created and managed. Discuss the concept of a race condition, how it occurs, and various mechanisms (e.g., synchronized blocks, locks, volatile keyword) to prevent or handle them.
- 06
Spring Bean Scopes
Explain the different bean scopes available in the Spring Framework (e.g., singleton, prototype, request, session, global session, application, websocket) and when to use each.
- 07
Singleton Design Pattern
Explain the Singleton design pattern, its purpose, and provide a Java implementation. Discuss common challenges (e.g., thread safety, reflection, serialization) and ways to address them.
- 08
Database Indexing with B-Trees
Explain the concept of B-trees and B+ trees, and how they are fundamental data structures used for indexing in most relational databases. Discuss their advantages in disk-based storage and query performance.
- 09
Anomaly Detection Concepts
Discuss the basic concepts of anomaly detection. What are anomalies, why is their detection important, and what are some general approaches or techniques (e.g., statistical, machine learning-based) used to identify them?
- 10
Diamond Problem in Java
Explain the 'Diamond Problem' in the context of multiple inheritance and how Java addresses this issue, particularly with interfaces and default methods.
Pubmatic interview questions FAQ
What questions are asked in Pubmatic interviews?
Candidates reported 19 distinct questions across 2 Pubmatic interviews. 6 coding and DSA questions, 3 system design questions, 10 other questions.
How difficult are Pubmatic interview questions?
Of the questions candidates rated, 57% were easy, 29% medium and 14% hard.