Unacademy Software Engineer Interview Questions and Answers

Q1. Check if string is palindrome
Ans. 
Check if a string is the same forwards and backwards
• Iterate through the string from both ends and compare characters

• Use built-in functions like reverse() to check for palindrome

• Ignore spaces and punctuation when checking for palindrome
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Two dynamic programming challenges at the hard level on LeetCode and 10 medium-level SQL challenge.

Q1. Machine coding round design drivezy app. It should be demoable.
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Q1. Add 2 linked list and return final linked list
Ans. 
Add 2 linked lists and return final linked list
• Create a new linked list to store the sum

• Traverse both linked lists simultaneously and add the corresponding nodes

• Handle carry over while adding nodes

• If one linked list is longer than the other, add the remaining nodes to the sum list
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Q2. Find a Element in rotated sorted array
Ans. 
Finding an element in a rotated sorted array.
• Use binary search to find the pivot point where the array is rotated.

• Determine which half of the array the target element is in.

• Perform binary search on that half of the array to find the target element.

• Handle edge cases such as when the target element is at the pivot point.
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Q1. Matrix chain multiplication
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Q2. Find word in matrix.
Ans. 
Given a matrix of characters and a word, find if the word exists in the matrix.
• Traverse the matrix and check if the first letter of the word matches any cell.

• If it does, check if the adjacent cells match the next letter of the word.

• Repeat until the entire word is found or no match is found.
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Q1. Stock buy sell problem to maximize profit.
Ans. 
Algorithm to maximize profit by buying and selling stocks.
• Iterate through the array of stock prices

• Keep track of the minimum price seen so far

• Calculate the profit if sold at current price

• Update maximum profit seen so far

• Return maximum profit
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Q1. Difference between var, let, const.
Ans. 
var, let, and const are all used to declare variables in JavaScript, but they have different scoping rules and behaviors.
• var has function scope and can be redeclared and reassigned

• let has block scope and can be reassigned but not redeclared

• const has block scope and cannot be reassigned or redeclared

• Use const for values that won't change, let for values that will, and avoid var
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Q2. Explain CSS box model. Do padding and margin apply to inline elements?
Ans. 
CSS box model defines the layout of elements on a webpage. Padding and margin can apply to block-level elements but not to inline elements.
• CSS box model consists of content, padding, border, and margin around an element.

• Padding adds space inside the border of an element.

• Margin adds space outside the border of an element.

• Padding and margin can apply to block-level elements like <div> but not to inline elements lik
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Q3. Difference between arrow functions and regular ones.
Ans. 
Arrow functions are shorter syntax for writing function expressions.
• Arrow functions do not have their own 'this' keyword.

• Arrow functions cannot be used as constructors.

• Arrow functions do not have the 'arguments' object.

• Arrow functions are more concise and easier to read.

• Regular functions are better for methods and constructors.
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Q4. How does JavaScript asynchronous model work
Ans. 
JavaScript asynchronous model allows non-blocking code execution by using callbacks and promises.
• JavaScript uses an event loop to handle asynchronous operations.

• Callbacks are functions passed as arguments to other functions and executed when the operation is complete.

• Promises are objects that represent the eventual completion or failure of an asynchronous operation.

• Async/await is a newer syntax that allows writing asyn...read more
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Q1. Major on Tech Stack , you are working on.
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Q1. Tell me about yourself
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Q2. Coding Question
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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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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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