Avanti Learning Centres 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.

Q1. Q1 difference between let and const
Ans. 
let is mutable and can be reassigned, const is immutable and cannot be reassigned
• let allows reassignment of values, const does not

• const must be initialized with a value, let can be declared without a value

• const is block-scoped, let is function-scoped
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Q2. Q2 what are closures?
Ans. 
Closures are functions that have access to variables from their containing scope even after the parent function has finished executing.
• Closures allow functions to maintain access to variables from their parent scope

• They are created when a function is defined within another function

• Closures are commonly used in event handlers and callbacks
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Q3. Q3. What is typeof null
Ans. 
typeof null returns 'object' in JavaScript.
• typeof null is 'object' in JavaScript

• This is a historical bug in JavaScript that has not been fixed for backward compatibility

• Example: console.log(typeof null) will output 'object'
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Q1. Q1. Find palindrome strings in an array of strings.
Ans. 
Finding palindrome strings in an array of strings.
• Iterate through each string in the array.

• For each string, check if it is equal to its reverse to determine if it is a palindrome.

• Store palindrome strings in a separate array or print them out.
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Q2. Q2. Explain debouncing with example.
Ans. 
Debouncing is a technique used to limit the rate at which a function is called.
• Debouncing is used to prevent multiple rapid calls to a function, typically in response to user input.

• It involves setting a delay before allowing the function to be called again.

• Example: Debouncing a search input field to only trigger the search function after the user has stopped typing for a certain period.
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Q1. What is react, diff between react and angular, deep copy shallow copy, hoisting, diff between props and state
Ans. 
React is a JavaScript library for building user interfaces. It is different from Angular in various ways.
• React is a library while Angular is a framework

• React uses virtual DOM while Angular uses real DOM

• React is more flexible and easier to learn than Angular

• Deep copy creates a new object with the same values while shallow copy creates a new reference to the same object

• Hoisting is a JavaScript mechanism where variables a...read more
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Q2. Implement custom hooks and array flat method
Ans. 
Implement custom hooks and array flat method
• Custom hooks are reusable functions that allow you to extract component logic into reusable functions

• Array flat method is used to flatten an array of nested arrays into a single array

• To implement custom hooks, create a function that uses the useState and useEffect hooks

• To implement array flat method, use the reduce method to flatten the array
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Q1. Concepts of node and Js
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Q1. Question on Binary trees: if symmetric, easy string question using hashmap
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Q2. If we are hosting a live test how to show real time ranking, HLD for this and what algorithms can we use
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Q1. Database schema design for a feature where user can be free, gold, platinum.
Ans. 
Use a user table with a column for user type (free, gold, platinum)
• Create a user table with columns for user ID, name, email, user type

• Use a separate table for user types with columns for type ID and type name

• Establish a one-to-many relationship between user and user type tables

• Example: user table - user_id, name, email, type_id; user_type table - type_id, type_name
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Q1. HLD for live rank dashboard for a live test where millions of users are doing test
Ans. 
High-level design for a live rank dashboard for a live test with millions of users.
• Use a scalable architecture to handle millions of users concurrently.

• Implement real-time data processing to update ranks dynamically.

• Utilize caching mechanisms to improve performance and reduce load on the database.

• Design a user-friendly interface with intuitive data visualization.

• Include features for filtering, sorting, and searching to
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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.