Pubmatic

Role: Not Specified (Likely SDE)

College: Not Specified

Interview Date: October 13, 2024

Interview Type: Not Specified

Result: Not Specified

Difficulty: Not Specified

Rounds: 4 rounds

Topics Asked: DSA, System Design, DBMS, OS, Behavioral.

Experience:

This is a general interview experience at PubMatic.

Round 1:
Coding questions included: Print the circumference of a tree; Given an array as stock prices, find the day when the user should buy and sell to maximize profit; Create a mirror tree from a given tree; Given a Binary tree of strings, return the stream of string as char* so that when reverse parsing, the same string gives back the same tree; Given a sorted and rotated array, find a given number in that.

Round 2:
Questions covered: Signature and return type of malloc; How does free() know the size of the block to be freed because malloc only returns the starting address; Given a service provider (e.g., Idea, Airtel), design a DB schema for storing all the information (focused on normalization and use of indexes); Given a table employee (id, name, manager id), write a query to return employee name and manager name; Given a stream of billion numbers, find the top 100 numbers at any instant of time.

Round 3:
This round included: Given a stream of 200 billion numbers (each number > 50000), find the average of numbers (main focus on how to store the average); Crossword puzzle algorithm (given a dictionary and an mXn grid, find how many possible words can be formed from the grid); Given an array of size m (m < n) and numbers from 1 to n, where n-m numbers are missing, find the missing numbers (e.g., for n=10, m=5, array=, missing are 2,3,5,9,10); Use cases of storing a tree into a stream; Given two dice and numbers 0-9, give every side of the dice a number so that they can be used to display dates of all the months.

Final Round with VP:
Behavioral and problem-solving questions included: Why do you want to join PubMatic?; Where do you see yourself in 5 years?; Given an array, find the number of triangles that can be formed; What do you prefer, array or linked list?; What do you prefer between a linked list and a doubly linked list?; What is your unique talent that distinguishes you from others?