Hippo Stores 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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Q1. Unique elements in an array using es6
Ans. 
Using Set and spread operator to get unique elements in an array.
• Create a Set from the array using Set constructor

• Use spread operator to convert Set back to array

• Alternatively, use Array.from() method to convert Set to array
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Coding question of react application.

Q1. Project related discussion.
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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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Q1. Basic JS & React concepts
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System design on the frontned application

Moderate level. It was easy to crack. There was few aptitude and coding questions associated

Q1. Questions on SQL
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Q1. Tell me about yourself
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Q2. Tell positive and negative points about you
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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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