Walmart Full Stack Developer Interview Questions and Answers

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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Q1. Why string arr immutable
Ans. 
String arrays are immutable because they cannot be changed once created.
• Strings in an array cannot be modified individually

• Any changes to a string array result in a new array being created

• Immutable arrays ensure data integrity and prevent unintended side effects
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Q2. How we can create a custom immutable class
Ans. 
To create a custom immutable class, use final keyword for class, private final fields, and no setter methods.
• Use the final keyword for the class to prevent inheritance

• Declare all fields as private and final to prevent modification

• Do not provide setter methods for the fields to maintain immutability

• Provide getter methods to access the fields
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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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Coding test contains 2 questions 1 moderate and 1 easy level

Q1. Asked about DSA,Heap sort,Merge sort.
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Q1. Tell me about yourself
Ans. 
I am a passionate software developer with experience in Java, Python, and web development.
• Graduated with a degree in Computer Science

• Worked on various projects using Java and Python

• Familiar with web development technologies like HTML, CSS, and JavaScript
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Q2. Why Lowe's,how can Lowe's improve its customer services
Ans. 
I believe Lowe's is a reputable company with a strong focus on customer satisfaction. They can improve their customer services by implementing personalized recommendations, enhancing their online platform, and providing better in-store experiences.
• Implement personalized recommendations based on customer preferences and purchase history

• Enhance the online platform for easier navigation, product search, and checkout proce...read more
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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

Round duration - 60 Minutes
Round difficulty - Medium

Explain Higher Order Functions in javascript.
What is the difference between tag and tag?

Q1. 
Sort Array of Strings Problem Statement
Given an array of strings ARRSTR[] of size N, and a character C, your task is to sort the ARRSTR[] array according to a new alphabetical order that starts with the ...read more
Ans. 
Sort an array of strings based on a new alphabetical order starting with a given character.
• Iterate through the array of strings and compare each string based on the new alphabetical order starting with the given character.

• Implement a custom sorting function that considers the new alphabetical order.

• Return the sorted array of strings.
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Round duration - 60 minutes
Round difficulty - Medium

List the different types of relationships in SQL.
What is an Alias in SQL?

Q1. 
Relative Sorting Problem Statement
You are given two arrays, 'ARR' of size 'N' and 'BRR' of size 'M'. Your task is to sort the elements of 'ARR' such that their relative order matches that in 'BRR'. Any e...read more
Ans. 
Sort elements of ARR to match relative order in BRR, append missing elements at the end in sorted order.
• Create a hashmap to store the index of elements in BRR for quick lookup.

• Sort elements in ARR based on their index in BRR, append missing elements at the end.

• Handle edge cases like empty arrays or duplicate elements in ARR and BRR.
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Excel Sheet Column Number Problem Statement
You are provided with a string STR representing a column title in an Excel Sheet. Your task is to determine the corresponding column number.
Example:
A typica...read more
Ans. 
Convert Excel sheet column title to corresponding column number.
• Iterate through the characters in the string from right to left, starting with a result of 0.

• For each character, calculate its value by subtracting 'A' and adding 1, then multiply by 26 raised to the power of its position from the right.

• Add up all the calculated values to get the final column number.

• Example: For input 'AB', A=1, B=2, so result = (1 * 26^1)
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. Why do you want to join Lowe's?
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Q1. Tell me about yourself
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Q1. How it will work or what is the type of XYZ
Ans. 
The type of XYZ is a software platform that utilizes machine learning algorithms to analyze data and provide insights.
• XYZ is a software platform

• It uses machine learning algorithms to analyze data

• It provides insights based on the analyzed data

• Examples of use cases include fraud detection, predictive maintenance, and customer segmentation
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