Toppr Software Engineer Interview Questions and Answers

Easy leetcode code 2 questions , HTML5 css javascript simple screen design

Q1. Oop, Simple coding javascript, react basic, sql basic
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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. 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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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. 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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