Landmark Group Front end Developer Interview Questions and Answers

Q1. Prototype read values from url map vs for
Ans. 
Reading values from URL using map vs for loop in JavaScript
• Use the window.location.search property to get the query string from the URL

• Map can be used to transform each value in the query string array

• For loop can be used to iterate through each value in the query string array
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Q1. Create ui component to display matched results in dropdown
Ans. 
Create a UI component to display matched results in a dropdown
• Use HTML, CSS, and JavaScript to create the dropdown component

• Implement a search functionality to filter and display matched results

• Use event listeners to handle user interactions like selecting a result
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Q1. Frontend design -
Ans. 
Frontend design involves creating the user interface of a website or application.
• Focus on user experience and usability

• Use responsive design for different screen sizes

• Implement accessibility features for users with disabilities
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Round duration - 60 Minutes
Round difficulty - Medium

There were 2 coding questions given in this round. One was related to Dynamic Programming and the second one was related to Recursion and Number Theory.

Q1. 
House Robber Problem Statement
Mr. X is a professional robber with a plan to rob houses arranged in a circular street. Each house has a certain amount of money hidden, separated by a security system that ...read more
Ans. 
House Robber problem where a robber wants to maximize stolen money without robbing adjacent houses in a circular street.
• Use dynamic programming to keep track of maximum stolen money at each house.

• Consider two cases: either rob the current house and skip the next, or skip the current house.

• Handle circular arrangement by considering the first and last houses separately.

• Example: For arr[] = {2, 3, 2}, the output is 3. Rob...read more
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Q2. 
Nth Fibonacci Number Problem Statement
Calculate the Nth term in the Fibonacci sequence, where the sequence is defined as follows: F(n) = F(n-1) + F(n-2), with initial conditions F(1) = F(2) = 1.
Input:
...read more
Ans. 
Calculate the Nth Fibonacci number efficiently using dynamic programming.
• Use dynamic programming to store and reuse previously calculated Fibonacci numbers.

• Start with base cases F(1) and F(2) as 1, then calculate subsequent Fibonacci numbers.

• Optimize the solution to avoid redundant calculations by storing intermediate results.

• Time complexity can be reduced to O(N) using dynamic programming.

• Example: For N = 5, the 5th F
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Round duration - 50 Minutes
Round difficulty - Medium

Standard Data Structures and Algorithms round where I was given 2 questions to solve , one was from Linked List and the other was related to Priority Queue / Quick Sort .

Q1. 
Intersection of Linked Lists Problem Statement
You are provided with two linked lists, L1 and L2, both sorted in ascending order. Generate a new linked list containing elements that exist in both linked l...read more
Ans. 
Given two sorted linked lists, find the intersection of elements in both lists and return a new sorted linked list.
• Traverse both linked lists simultaneously to find common elements

• Create a new linked list to store the intersecting elements

• Ensure the final linked list is sorted in ascending order

• Handle cases where there are no common elements between the lists
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Q2. 
Kth Largest Element Problem Statement
Ninja enjoys working with numbers, and Alice challenges him to find the Kth largest value from a given list of numbers.
Input:
The first line contains an integer 'T...read more
Ans. 
Find the Kth largest element in a given list of numbers.
• Sort the array in descending order.

• Return the Kth element from the sorted array.

• Handle multiple test cases efficiently.
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Round duration - 50 Minutes
Round difficulty - Easy

This round majorly focused on Real life appications of Data Structures and also revolved around Object Oriented Programming Style of writing code .

Q1. 
Data Structure with Insert, Delete, and GetRandom Operations
Design a data structure that supports four operations: insert an element, remove an element, search for an element, and get a random element. E...read more
Ans. 
Design a data structure with insert, delete, search, and getRandom operations, all in constant time.
• Use a combination of HashMap and ArrayList to achieve constant time operations.

• For insert operation, add the element to the ArrayList and store its index in the HashMap.

• For delete operation, swap the element to be deleted with the last element in the ArrayList, update the index in the HashMap, and then remove the last el...read more
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Q2. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.
• Implement a doubly linked list to maintain the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access.

• When capacity is reached, evict the least recently used item before inserting a new item.

• Update the position of a key in the linked list whenever it is accesse
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Round duration - 45 Minutes
Round difficulty - Medium

This round was inclined towards some Low Level Design Principles and some concepts from Java .

Q1. Design a Railway Reservation System.
Ans. 
Design a Railway Reservation System
• Create a database to store train schedules, seat availability, and passenger information

• Implement a user interface for users to search for trains, book tickets, and view their reservations

• Include features like seat selection, payment processing, and ticket confirmation

• Handle scenarios like waitlisting, cancellations, and refunds

• Ensure data security and privacy of passenger information
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Q2. Why is Java considered platform-independent while the Java Virtual Machine (JVM) is platform-dependent?
Ans. 
Java is platform-independent because the code is compiled into bytecode that can run on any platform with a JVM, which is platform-dependent due to its reliance on the underlying hardware and operating system.
• Java code is compiled into bytecode, which can run on any platform with a JVM.

• JVM acts as an interpreter that translates bytecode into machine code specific to the underlying hardware and operating system.

• The JVM ...read more
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Round duration - 90 Minutes
Round difficulty - Medium

This Round was DS and Algo round and it started with formal introduction, followed by 2 problems. We first dicussed the approach the time complexity and proper code covering all cases.

Q1. 
Minimum Cost to Buy Oranges Problem Statement
You are given a bag of capacity 'W' kg and a list 'cost' of costs for packets of oranges with different weights. Each element at the i-th position in the list...read more
Ans. 
Find the minimum cost to buy a specific weight of oranges using given cost list.
• Iterate through the cost list and find the minimum cost to achieve the desired weight

• Keep track of the minimum cost while considering available packet weights

• Return -1 if it is not possible to buy exactly W kg of oranges
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Q2. 
K - Sum Path In A Binary Tree
Given a binary tree where each node contains an integer value, and a value 'K', your task is to find all the paths in the binary tree such that the sum of the node values in ...read more
Ans. 
Find all paths in a binary tree where the sum of node values equals a given value 'K'.
• Traverse the binary tree using DFS and keep track of the current path and its sum.

• At each node, check if the current sum equals 'K' and add the path to the result if true.

• Continue traversal to the left and right child nodes recursively.

• Return the list of paths that sum up to 'K'.
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Round duration - 40 Minutes
Round difficulty - Medium

This round majorly focused on puzzles and some questions revolving around Computer Networks and the projects in my resume .

Q1. You have two wires of different lengths that take different times to burn. How can you measure a specific amount of time using these two wires?
Ans. 
Use two wires of different lengths to measure a specific amount of time by burning them simultaneously.
• Burn both wires at the same time, one wire will burn faster than the other.

• Measure the time it takes for the faster burning wire to completely burn.

• Calculate the specific amount of time by using the ratio of the lengths of the two wires.
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Q2. You have 3 ants located at the corners of a triangle. The challenge is to determine the movement pattern of the ants if they all start moving towards each other. What will be the outcome?
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. What do you know about the company?
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Q2. Why should we hire you?
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Round duration - 90 minutes
Round difficulty - Medium

This was a proctured online coding round where we had 2 questions to solve under 90 minutes . The questions were of easy to medium level I would say with some lenghty implementations .

Q1. 
Minimum Numbers Required Problem Statement
Given an array 'ARR' consisting of N integers, along with two integers, 'SUM' and 'MAXVAL', you need to determine the minimum number of integers to be added to t...read more
Ans. 
Determine the minimum number of integers to be added to an array to make its sum equal to a given value.
• Iterate through the array and calculate the current sum.

• Determine the difference between the target sum and the current sum.

• Add the minimum number of integers within the range of -MAXVAL to MAXVAL to reach the target sum.
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Q2. 
Maximum Sum Subsequence Problem Statement
Given an array of integers NUMS consisting of N integers and an integer K, determine the maximum sum of an increasing subsequence with exactly K elements.
Exampl...read more
Ans. 
Find the maximum sum of an increasing subsequence with exactly K elements in an array of integers.
• Iterate through the array and maintain a dynamic programming table to store the maximum sum of increasing subsequences ending at each index.

• For each element, check all previous elements to find the increasing subsequence with maximum sum ending at that element.

• Update the dynamic programming table with the maximum sum found...read more
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Round duration - 50 Minutes
Round difficulty - Medium

Standard Data Structures and Algorithms round . One has to be fairly comfortable in solving algorithmic problems to
pass this round with ease.

Q1. 
Check Whether Binary Tree Is Complete
You have been given a binary tree and your task is to determine if it is a Complete Binary Tree or not.
A Complete Binary Tree is defined as a binary tree where ever...read more
Ans. 
Check if a binary tree is a Complete Binary Tree or not based on given criteria.
• Traverse the binary tree level by level and check if all levels are completely filled except the last one.

• Ensure all nodes at the last level are positioned at the leftmost side.

• Use level order traversal to check for completeness of the binary tree.

• Example: For input 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1, the output should be 1.
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Q2. 
Consecutive Elements
Given an array arr of N non-negative integers, determine whether the array consists of consecutive numbers. Return true if they do, and false otherwise.
Input:
The first line of inp...read more
Ans. 
Check if an array of integers consists of consecutive numbers.
• Iterate through the array and check if the absolute difference between consecutive elements is 1.

• Sort the array and check if the elements are consecutive.

• Use a set to store the elements and check if the size of the set is equal to the length of the array.
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Round duration - 40 Minutes
Round difficulty - Medium

This round majorly focused on my projects and some standard questions revolving around Operating Systems and DBMS.

Q1. How can you print numbers from 1 to 100 using more than two threads in an optimized approach?
Ans. 
Use multiple threads to print numbers from 1 to 100 in an optimized approach.
• Divide the range of numbers (1-100) among the threads to avoid duplication.

• Use synchronization mechanisms like mutex or semaphore to ensure proper order of printing.

• Consider using a shared data structure like a queue to coordinate the threads.

• Implement a mechanism to signal the threads when to start and stop printing.
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Q2. What are the advantages of using views in a database management system?
Ans. 
Views in a database management system provide data security, simplify complex queries, and improve performance.
• Enhanced security by restricting access to certain columns or rows

• Simplify complex queries by pre-defining joins and filters

• Reduce redundancy by storing commonly used queries as views

• Improve performance by storing pre-processed data in views

• Allow for data abstraction, making it easier to work with complex data
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. What do you know about the company?
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Q2. Why should we hire you?
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Round duration - 60 minutes
Round difficulty - Medium

The platform was HackerEarth time duration was 1 hour.
1.) 25 MCQs (Both Easy and Gate Level Based) 
2.) 1 Coding Question, that needs to be solved in O(logn) time. Program for Fibonacci numbers. The basic idea behind that question is we need to crack the pattern and then based on constraints we need to solve it.

Q1. 
Nth Fibonacci Number Problem Statement
Given an integer 'N', the task is to compute the N'th Fibonacci number using matrix exponentiation. Implement and return the Fibonacci value for the provided 'N'.
N...read more
Ans. 
Use matrix exponentiation to efficiently compute the Nth Fibonacci number modulo 10^9 + 7.
• Implement matrix exponentiation to calculate Fibonacci numbers efficiently.

• Use the formula F(n) = F(n-1) + F(n-2) with initial values F(1) = F(2) = 1.

• Return the result modulo 10^9 + 7 to handle large Fibonacci numbers.

• Optimize the solution to achieve better than O(N) time complexity.
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Round duration - 40 minutes
Round difficulty - Medium

It was a technical round. The platform was Zoom time duration was 40 mins. Started with Tell me something about yourself.
 

Q1. 
Similar Strings Problem Statement
Determine whether two given strings, A and B, both of length N, are similar by returning a 1 if they are, otherwise return a 0.
Explanation:
String A is similar to stri...read more
Ans. 
Determine if two strings are similar based on given conditions.
• Check if the strings are equal first.

• Then check if the strings can be divided into two halves with similar patterns.

• Return 1 if the strings are similar, 0 otherwise.
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Round duration - 45 Minutes
Round difficulty - Medium

The platform was Zoom time duration was 1 hour 45 mins. Started with Tell me something about yourself. I told them, that I like solving algorithms, so she was like let’s start with trees then.

 

Round duration - 30 minutes
Round difficulty - Medium

This was a Hiring Manager Round. The platform was Zoom time duration was 30 mins. Started with Tell me something about yourself.


 

Round duration - 20 minutes
Round difficulty - Easy

The platform was Zoom time duration was 20 mins. Asked me to give my introduction.

 

Round duration - 90 minutes
Round difficulty - Medium

Round duration - 60 minutes
Round difficulty - Medium

This was the technical round, held around at 10 AM IST on Google Meet.
Firstly she greeted me and asked me to tell something about myself, to which I introduced myself, explaining my academic and some projects also.
After that we moved on to the Hackathon project, which was smart cart self-checkout system. I explained the project along with the code, wherever necessary.
Every word you say while explaining should be clear to you.I used Firebase and SQL while explaining my project, to which she asked some questions related to it, 
Then she moved to the DBMS part, types of joins,what is indexing, how to approach if you were to design a payment system.
At last she asked me some Data Structure questions, which were of medium complexity

Q1. 
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 'K'.
• Traverse the list to find the length 'N' of the linked list.

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

• Traverse the list again and remove the node at the calculated position.
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Q2. 
House Robber Problem Statement
Consider Mr. X, a professional robber who is planning to rob houses along a street. These houses are arranged in a circle, which means the first house is a neighbor to the l...read more
Ans. 
House Robber problem where adjacent houses have connected security system, find maximum money Mr. X can rob without triggering security.
• Use dynamic programming to keep track of maximum money robbed at each house.

• At each house, decide whether to rob the current house or skip it based on maximum money robbed so far.

• Handle the circular nature of houses by considering two cases: robbing the first house and not robbing the ...read more
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Round duration - 30 minutes
Round difficulty - Easy

The interviewer was very frank and cheerful. This was held at 2:30 PM IST on Google Meet.
He firstly greeted me and asked me how I was doing.
How was my previous round, any technical difficulties?
Then he asked me to introduce myself.
He started telling about his journey to Lowe's and his technical background.
Then he asked some HR related questions

Basic java question, design questions, 1 data structure question

Q1. Asked puzzle and previous project experience
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Q2. Monitor microservices using Spring actuator
Ans. 
Spring Actuator provides endpoints to monitor and manage microservices in a Spring Boot application.
• Add Spring Boot Actuator dependency in pom.xml

• Enable Actuator endpoints in application.properties or application.yml

• Access Actuator endpoints like /actuator/health, /actuator/info, etc.

• Customize Actuator endpoints using configuration properties
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Q3. How webflux works
Ans. 
Webflux is a reactive programming framework for building non-blocking, event-driven applications on the JVM.
• Webflux is part of the Spring Framework and provides support for reactive programming.

• It allows developers to build asynchronous, non-blocking applications that can handle a large number of concurrent connections.

• Webflux uses Project Reactor, a reactive library for building reactive applications.

• It supports both ...read more
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2 DSA questions and some MCQ on Java and Spring

Q1. Longest palindromic substring
Ans. 
A palindromic substring is a string that reads the same forwards and backwards.
• Use dynamic programming to find the longest palindromic substring.

• Start by considering each character as the center of a potential palindrome.

• Expand outwards from each center to check for palindromes of odd and even lengths.
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Q2. Remove duplicates in place from a 1D array
Ans. 
Remove duplicates from a 1D array of strings in place
• Iterate through the array and use a HashSet to keep track of unique elements

• Replace duplicates with null or an empty string to remove them in place
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Q1. Project discussion
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Q2. Search min element in a rotated sorted array with duplicate elements
Ans. 
Search for the minimum element in a rotated sorted array with duplicate elements.
• Use binary search to find the minimum element in the rotated sorted array.

• Handle the case where duplicate elements are present by adjusting the search conditions.

• Consider cases where the array is not rotated or contains only one element.
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Q3. Ways of declaring singleton class
Ans. 
A singleton class is a class that can only have one instance created throughout the application.
• Declare a private static instance variable of the class

• Create a private constructor to prevent external instantiation

• Provide a public static method to access the instance
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Q1. Project discussion
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Q2. Behavioural questions
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