Lido Learning Software Developer Intern Interview Questions, Process, and Tips

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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2 hrs duration with 2 easy level dsa questions and 15 around mcqs based on core cs concepts.

Q1. Implement stack using linked list.
Ans. 
Implementing stack using linked list
• Create a Node class with data and next pointer

• Create a Stack class with top pointer

• Implement push() method to add element to top of stack

• Implement pop() method to remove element from top of stack

• Implement peek() method to return top element without removing it
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Q2. Print first duplicate value in a string.
Ans. 
Find the first duplicate value in an array of strings.
• Create a hash table to store the frequency of each string.

• Iterate through the array and check if the string already exists in the hash table.

• If it does, return the string. If not, add it to the hash table.

• If no duplicates are found, return null or an appropriate message.
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Round duration - 135 minutes
Round difficulty - Easy

There was no sectional time limit for the coding questions.The test was online with audio and video both on for continuous monitoring.

Q1. 
N-th Term Of Geometric Progression
Find the N-th term of a Geometric Progression (GP) series given the first term A, the common ratio R, and the term position N.
Explanation:
The general form of a GP se...read more
Ans. 
Calculate the N-th term of a Geometric Progression series given the first term, common ratio, and term position.
• Use the formula A * R^(N-1) to find the N-th term of the GP series.

• Remember to return the result modulo 10^9 + 7 as the term can be very large.

• Handle multiple test cases efficiently by iterating through each case.
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Q2. 
Matrix Element Cube Sum Problem
For a given M x N sized 2D array 'MATRIX', find and return the value of (i * i + j * j) for elements where the sum of the cubes of its digits equals the element itself. Her...read more
Ans. 
Find and return the value of (i * i + j * j) for elements in a 2D array where the sum of the cubes of its digits equals the element itself.
• Iterate through the 2D array and check if the sum of the cubes of digits equals the element itself.

• Calculate (i * i + j * j) for elements that satisfy the condition.

• Return the calculated values as a new 2D array.

• If no element satisfies the condition, return -1.
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Round duration - 40 minutes
Round difficulty - Easy

The interviewer was very calm and listened very carefully to the solutions. There was a lot of discussion on my projects and the interviewer seems to be very interested in knowing about the workflows of my projects.They also give me some coding questions which were related to problem solving also.

Q1. 
Distinct Subsequences Problem Statement
You are given a string 'S' of length 'N' which may include duplicate alphabets. Your goal is to calculate the number of distinct subsequences in the string.
Exampl...read more
Ans. 
Calculate the number of distinct subsequences in a string with possible duplicates.
• Use dynamic programming to keep track of the count of distinct subsequences for each character in the string.

• Consider the cases where the current character is included or excluded in the subsequence.

• Handle duplicates by using a hashmap to store the last occurrence index of each character.

• Modulo the final count by 10^9 + 7 to avoid overfl
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Q2. 
Remove the Kth Node from the End of a Linked List
You are given a singly Linked List with 'N' nodes containing integer data and an integer 'K'. Your task is to delete the Kth node from the end of this Lin...read more
Ans. 
Remove the Kth node from the end of a singly linked list given the position from the end to be removed.
• Traverse the list to find the length 'N' of the linked list.

• Calculate the position from the beginning to be removed as 'N - K + 1'.

• Delete the node at the calculated position from the beginning.
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Q3. 
Common Elements Problem Statement
Identify and output the common strings present in both given arrays of lowercase alphabets for each test case.
Input:
The first line contains an integer 'T' representin...read more
Ans. 
The task is to find common strings in two arrays of lowercase alphabets for each test case.
• Iterate through the elements of the second array and check if they are present in the first array.

• Use a hash set to store the strings of the first array for efficient lookup.

• Return the common strings in the order they appear in the second array.
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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. Sdlc lifecycle of components and architecture.
Ans. 
SDLC lifecycle involves planning, designing, developing, testing, deploying, and maintaining software components and architecture.
• SDLC (Software Development Life Cycle) includes phases like planning, designing, coding, testing, and maintenance.

• Components are designed, developed, tested, and integrated into the overall architecture.

• Architecture involves defining the structure, behavior, and interactions of software comp...read more
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Q1. Role and responsibility my tasks and questions on project
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Round duration - 70 minutes
Round difficulty - Easy

We're provided with 60 minutes.
We're provided with desktop as it was online test.

Q1. 
Leap Year Checker
Determine if a given year, represented as an integer 'N', is a leap year.
A leap year is defined as a year with 366 days, unlike a normal year which has 365 days.
Input:
The initial i...read more
Ans. 
The task is to determine if a given year is a leap year or not.
• Check if the year is divisible by 4, if yes then proceed to next step

• If the year is divisible by 100, then it should also be divisible by 400 to be a leap year

• If the year satisfies both conditions, output 'Yes', else output 'No'
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Round duration - 25 minutes
Round difficulty - Easy

They basically ask questions related to operating system

Round duration - 15 minutes
Round difficulty - Easy

There were 2 interviewers who talked to me and ask different questions regarding my company, my experience in college etc.
It was kind of chit chat but basically they were testing my conversation skills.