Landmark Group Senior Application Developer Interview Questions and Answers

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.

 

Q1. What is the role of exception handling in programming, and how is the 'finally' block used in this context, as well as the process of throwing exceptions?
Ans. 
Exception handling is crucial in programming to handle errors and ensure proper execution. The 'finally' block is used to clean up resources, and throwing exceptions allows for error propagation.
• Exception handling is used to manage errors and unexpected situations in a program.

• The 'finally' block is used to execute code that should always run, regardless of whether an exception is thrown or not.

• Throwing exceptions allo...read more
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Q2. What are the differences between SQL and NoSQL databases, and can you mention some NoSQL databases that you are familiar with?
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Q3. What are the ACID properties implemented in your project, and can you provide a brief overview of the CAP Theorem?
Ans. 
ACID properties ensure data integrity in transactions. CAP Theorem states that a distributed system can only guarantee two out of three: Consistency, Availability, Partition Tolerance.
• ACID properties: Atomicity, Consistency, Isolation, Durability

• Example: In a banking application, a transfer of funds should be atomic, consistent, isolated, and durable

• CAP Theorem: Consistency, Availability, Partition Tolerance - a distri...read more
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Q4. Database disaster recovery?
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Q5. What is the difference between Comparable and Comparator in Java? And how to Implement in Collections.
Ans. 
Comparable is an interface used for natural ordering, while Comparator is used for custom ordering in Java Collections.
• Comparable interface is used to define the natural ordering of objects. It is implemented by the class whose objects are to be sorted.

• Comparator interface is used to define custom ordering of objects. It is implemented by a separate class.

• To implement Comparable, the class needs to override the compare...read more
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Q6. Implementation of Generics in Java
Ans. 
Generics in Java allow for creating classes, interfaces, and methods that operate on types parameterized at compile time.
• Generics provide type safety by allowing compile-time type checking.

• They enable code reusability and reduce the need for casting.

• Example: List<String> list = new ArrayList<>();
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Q1. Can you provide the code to reverse a string using recursion?
Ans. 
Code to reverse a string using recursion
• Create a recursive function that takes a string as input

• Base case: if the string is empty or has only one character, return the string

• Recursive case: return the last character of the string concatenated with the result of calling the function on the substring excluding the last character
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Q2. How does object comparison work with specific fields?
Ans. 
Object comparison with specific fields involves comparing values of selected fields between two objects.
• Object comparison can be done by comparing the values of specific fields in two objects.

• Fields can be selected based on unique identifiers or criteria for comparison.

• Example: Comparing the 'name' field of two person objects to check if they are the same.
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Q3. How does the distributed transactions being handled in a microservice?
Ans. 
Distributed transactions in microservices involve using compensating transactions and event-driven architecture.
• Microservices typically use compensating transactions to maintain consistency across multiple services.

• Event-driven architecture can help in coordinating distributed transactions by using events to trigger actions in different services.

• Implementing distributed transactions in microservices requires careful de...read more
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Q4. Aggregator Pattern in Microservice
Ans. 
Aggregator pattern is used in microservices architecture to combine multiple service responses into a single response.
• Aggregator pattern helps in reducing the number of client requests by combining multiple service responses.

• It can be implemented using a separate service or within an existing service.

• Example: A shopping website aggregating product information from different microservices like inventory, pricing, and re
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Q5. What is the implementation of the factory design pattern?
Ans. 
Factory design pattern is a creational pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
• Factory method pattern defines an interface for creating objects, but lets subclasses decide which class to instantiate.

• It promotes loose coupling by eliminating the need to bind application-specific classes into the code.

• Example: A car m...read more
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Q6. What is indexing in a database, and what data structures are commonly used for indexing?
Ans. 
Indexing in a database is a technique to improve the speed of data retrieval by creating a data structure that allows for quick lookup.
• Indexing involves creating a separate data structure that contains pointers to the actual data in the database.

• Common data structures used for indexing include B-trees, hash tables, and binary search trees.

• Indexes can be created on one or multiple columns in a database table to speed up...read more
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Q7. What is your approach to designing a system capable of handling thousands of requests?
Ans. 
My approach involves using load balancing, caching, asynchronous processing, and horizontal scaling.
• Implement load balancing to distribute requests evenly across multiple servers.

• Utilize caching mechanisms to store frequently accessed data and reduce response times.

• Use asynchronous processing for long-running tasks to free up resources for handling more requests.

• Implement horizontal scaling by adding more servers to ha...read more
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Q8. What is the CQRS pattern in microservices?
Ans. 
CQRS pattern in microservices separates read and write operations for improved scalability and performance.
• CQRS stands for Command Query Responsibility Segregation

• It separates the read and write operations into two different models

• Write operations update the data store, while read operations query a separate data store

• CQRS can improve performance and scalability by allowing each model to be optimized for its specific t
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Q9. What is the role of API Gateway in microservices architecture?
Ans. 
API Gateway acts as a single entry point for all client requests in a microservices architecture.
• API Gateway handles authentication, authorization, rate limiting, and routing of requests to appropriate microservices.

• It helps in decoupling client applications from individual microservices, providing a more flexible and scalable architecture.

• API Gateway can also perform tasks like request/response transformation, logging...read more
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Q10. Write SQL query to fetch data from two tables using joins?
Ans. 
SQL query to fetch data from two tables using joins
• Use the JOIN keyword to combine rows from two tables based on a related column

• Specify the columns to select from each table in the SELECT statement

• Use the ON keyword to specify the join condition
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Mostly dynamic programming and tree based programs

Q1. Coding Coordinate geometry problem
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Q2. Coding on trees
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Q1. HLD / LLD , Java technical questions
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Q2. Pair programming
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Q1. Asked about resume and then some questions on Linkedlist, Stack
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Q2. Java garbage collection
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Q3. What is Bean in Spring
Ans. 
A bean in Spring is a Java object that is instantiated, assembled, and managed by the Spring IoC container.
• Beans are defined in the Spring configuration file using XML or annotations.

• Beans are singleton by default but can be configured as prototype.

• Beans can have dependencies injected by the container.

• Example: @Component annotation in Spring creates a bean.

• Example:
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