Unacademy Software Engineer Interview Questions and Answers

Round duration - 120 minutes
Round difficulty - Easy

It was a mix of mathematical aptitude, logical ability, and puzzles along with 2 programming questions of easy and medium level. Time was enough and no sectional time was present. 1-2 MCQs on SQL were also present.

This round was immediately followed by an SHL aptitude test which was basically a quick limited time check of your verbal ability and math because many questions were to be done in 1 hour.

Q1. 
Boolean Matrix Transformation Challenge
Given a 2-dimensional boolean matrix mat of size N x M, your task is to modify the matrix such that if any element is 1, set its entire row and column to 1. Specifi...read more
Ans. 
Modify a boolean matrix such that if any element is 1, set its entire row and column to 1.
• Iterate through the matrix and mark rows and columns to be modified

• Use additional arrays to keep track of rows and columns to be modified

• Update the matrix in-place based on the marked rows and columns
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Round duration - 60 minutes
Round difficulty - Easy

It was an online video interview round on HackerEarth with simultaneous code option. It was mostly justifying your resume in the first 15 minutes. After that OOPS was majorly asked. Basics of programming including questions on STL were asked. A class which required inheritance was asked by the interviewer to write. I was helped by the interviewer if i got stuck somewhere, Some questions on implementation of hashmaps and priority queues were also asked. A puzzle was asked which luckily struct to me at that moment.

Coding test around front end using react

Round duration - 60 Minutes
Round difficulty - Easy

It was an coding round

Q1. 
The Skyline Problem
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette when viewed from a distance. Each building is ...read more
Ans. 
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette.
• Iterate through the buildings and create a list of critical points (x, y) where the height changes.

• Sort the critical points based on x-coordinate and process them to form the skyline.

• Merge consecutive horizontal segments of equal height into one to ensure no duplicates.

• Return the fin...read more
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Q2. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. 
Find all possible paths for a rat in a maze from source to destination.
• Use backtracking to explore all possible paths in the maze.

• Keep track of visited cells to avoid revisiting them.

• Recursively try moving in all directions (up, down, left, right) until reaching the destination.

• Return a list of strings representing valid paths sorted in alphabetical order.
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Round duration - 30 Minutes
Round difficulty - Easy

It was an HR round with some general questions. it was just for formality.

Q1. Concepts of node and Js
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There were 3 coding questions, all of them were medium level difficulty. Typically people who solved 2 questions correctly were shortlisted for the interview rounds.

Q1. Rainwater trapped question and some optimisations, after that some additional changes to the question were added.
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Q2. Print zigzag matrix
Ans. 
Prints a zigzag matrix
• Create a 2D array with the desired number of rows and columns

• Use nested loops to iterate through the array

• Alternate the direction of iteration to create the zigzag pattern

• Print the elements of the array in the desired format
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Q1. Explain about projects in deep and some questions related to that.
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Q2. Find a subset of an array having a target sum.
Ans. 
Given an array of strings, find a subset that adds up to a target sum.
• Use a recursive approach to explore all possible subsets

• Start with an empty subset and add elements one by one

• Keep track of the current sum and check if it matches the target sum

• If the sum exceeds the target, backtrack and remove elements

• Return the subset if found, otherwise return an empty subset
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Q1. Tell me a thing in which earlier you struggled and after some rigorous practice and dedication you excelled.
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Q2. Explain a moment in life where you showcased your leadership and collaborative skills.
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Q1. Explain about Event loop
Ans. 
Event loop is a mechanism that allows for asynchronous programming by handling events and callbacks.
• Event loop is responsible for handling and executing events and callbacks in a non-blocking manner.

• It continuously checks the event queue and processes events one by one.

• Event loop is commonly used in JavaScript for handling asynchronous operations like setTimeout, setInterval, and AJAX requests.
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Ask to create a database design and API for a todo list app

Q1. Why do you want to join Byjus
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There was 2 coding question
One was easy One was very Difficult
20 MCQ question from Operating system and DBMS

Q1. First question was binary search in unsorted arrays So here i have asked about sorting algorithms all sorting algorithms must be clear
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Q2. Second question was to find longest consecutive subarray.
Ans. 
Find the longest consecutive subarray.
• Iterate through the array and keep track of the current subarray length.

• Update the maximum length as you iterate.

• Reset the current subarray length when a non-consecutive element is encountered.
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Q1. OOPS related question Heap insertion deletion question Hashing Spanning tree
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Q2. Minimum Spanning tree Implementation of MST
Ans. 
Minimum Spanning Tree (MST) is a tree that connects all vertices in a graph with minimum total edge weight.
• MST can be found using Prim's algorithm or Kruskal's algorithm.

• Prim's algorithm starts with a single vertex and adds the closest vertex to the tree until all vertices are included.

• Kruskal's algorithm starts with the edges with the lowest weight and adds them to the tree as long as they don't create a cycle.

• MST has...read more
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