Lowe's Full Stack 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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Q1. Basic JS & React concepts
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System design on the frontned application

Q1. Laravel based questions
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Q1. Basic questions
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2 coding questions from dsa. one quest was from trees ds

Q1. Why did you choose target
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Q2. Minus points in you that you can share with us
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60m, Data structure and algo

Q1. Leetcode - smallest palindrome, Lowest common ancestor
Ans. 
Find the smallest palindrome and lowest common ancestor in a given tree
• To find the smallest palindrome, iterate through the string and check if it is a palindrome. Return the smallest one found.

• To find the lowest common ancestor in a tree, use a recursive approach to traverse the tree and find the common ancestor of two nodes.
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Round duration - 120 minutes
Round difficulty - Medium

This was the online round held at Hackerearth. All students who met the eligibility criteria were shared link for the online test on hackerearth.

Q1. 
Remove Consecutive Duplicates Problem Statement
Given a string str of size N, your task is to recursively remove consecutive duplicates from this string.
Input:
T (number of test cases)
N (length of the ...read more
Ans. 
Recursively remove consecutive duplicates from a given string.
• Use recursion to check for consecutive duplicates in the string.

• If current character is same as next character, skip the next character.

• Repeat the process until no consecutive duplicates are found.
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Q2. 
Deepest Leaves Sum Problem Statement
Given a binary tree of integers, your task is to calculate the sum of all the leaf nodes present at the deepest level of this binary tree. If there are no such nodes, ...read more
Ans. 
Calculate the sum of leaf nodes at the deepest level of a binary tree.
• Traverse the binary tree to find the deepest level of leaf nodes.

• Sum the leaf nodes at the deepest level.

• Handle null nodes represented by -1.

• Ensure the sum fits within a 32-bit integer.
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Round duration - 60 minutes
Round difficulty - Medium

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

Q1. 
Palindrome Permutation - Problem Statement
Determine if a permutation of a given string S can form a palindrome.
Example:
Input:
string S = "aab"
Output:
"True"
Explanation:
The permutation "aba" o...read more
Ans. 
Check if a permutation of a string can form a palindrome.
• Create a frequency map of characters in the string.

• Count the number of characters with odd frequencies.

• If there is at most one character with odd frequency, return true.

• Otherwise, return false.
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Q2. 
Word Presence in Sentence
Determine if a given word 'W' is present in the sentence 'S' as a complete word. The word should not merely be a substring of another word.
Input:
The first line contains an in...read more
Ans. 
Check if a given word is present in a sentence as a complete word.
• Split the sentence into words using spaces as delimiter.

• Check if the given word matches any of the words in the sentence.

• Ensure that the word is not just a substring of another word in the sentence.
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Round duration - 30 mintues
Round difficulty - Easy

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

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 a bit lengthy but the implementation part was quite easy .

Q1. 
Encode the Message Problem Statement
Given a text message, your task is to return the Run-length Encoding of the given message.
Run-length encoding is a fast and simple method of encoding strings, repres...read more
Ans. 
Implement a function to encode a text message using run-length encoding.
• Iterate through the message and count consecutive characters

• Append the character and its count to the encoded message

• Handle edge cases like single characters or empty message
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Q2. 
Make All Elements of the Array Distinct
Given an array/list ARR of integers with size 'N', your task is to determine the minimum number of increments needed to make all elements of the array distinct. You...read more
Ans. 
Find the minimum number of increments needed to make all elements of the array distinct by increasing any element by 1 in each operation.
• Iterate through the array and keep track of the frequency of each element.

• For each element with frequency greater than 1, increment it until it becomes distinct.

• Return the total number of operations needed to make all elements distinct.
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Round duration - 50 Minutes
Round difficulty - Easy

This Round was DS/Algo + Core round and it started with formal introduction, followed by 3 problems. We first dicussed the
approach the time complexity and proper code covering all cases for the 2 coding problems . The last question was related to OS and was a bit theoretical .

Q1. 
Distinct Characters Problem Statement
Given a string STR, return all possible non-empty subsequences with distinct characters. The order of the strings returned is not important.
Example:
Input:
STR = ...read more
Ans. 
Return all possible non-empty subsequences with distinct characters from a given string.
• Use a recursive approach to generate all possible subsequences with distinct characters.

• Keep track of the characters used in each subsequence to ensure uniqueness.

• Return the generated subsequences as an array of strings.
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Q2. 
Calculate Score of Balanced Parentheses
In this intellectual game, Ninja is provided with a string of balanced parentheses called STR. The aim is to calculate the score based on specific game rules. If Nin...read more
Ans. 
Calculate the score of a string of balanced parentheses based on specific game rules.
• Iterate through the string and keep track of the score based on the rules provided

• Use a stack to keep track of the scores of valid parentheses expressions

• For each '()', increment the score by 1; for '(x)', double the score of x

• Return the final computed score for the string
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Q3. Can you explain demand paging?
Ans. 
Demand paging is a memory management technique where pages are loaded into memory only when they are needed.
• Pages are loaded into memory on demand, rather than all at once.

• Helps in reducing the amount of physical memory needed.

• Improves overall system performance by allowing more processes to run simultaneously.

• Commonly used in modern operating systems like Linux and Windows.

• Example: When a program is executed, only the...read more
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Round duration - 40 Minutes
Round difficulty - Medium

I was given 2 preety good questions of DSA in this round . One was related to Binary Trees and the other was a good DP problem in which I struggled a bit but with some hints I was able to solve this problem too . The last question was related to OOPS and was preety easy .

Q1. 
Binary Tree Construction from Traversals Problem
Given the POSTORDER and PREORDER traversals of a binary tree, where the tree consists of N nodes with each node representing a distinct positive integer fr...read more
Ans. 
Construct a binary tree from given POSTORDER and PREORDER traversals.
• Use the first element in PREORDER as the root node

• Find the root node in POSTORDER to divide the tree into left and right subtrees

• Recursively construct left and right subtrees using the divided traversals
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Q2. 
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 given the cost of different weight packets.
• Iterate through the list of costs and find the minimum cost to achieve the desired weight.

• Keep track of the minimum cost for each weight up to the desired weight.

• Handle cases where a specific weight packet is unavailable by setting the cost to infinity.

• Return the minimum cost for the desired weight, or -1 if it is not p
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Q3. Can you explain the concepts of static and dynamic polymorphism in Object-Oriented Programming?
Ans. 
Static polymorphism is achieved at compile time through method overloading and overriding. Dynamic polymorphism is achieved at runtime through method overriding.
• Static polymorphism is also known as compile-time polymorphism.

• Dynamic polymorphism is also known as runtime polymorphism.

• Static polymorphism is achieved through method overloading, where multiple methods have the same name but different parameters.

• Dynamic poly...read more
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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. Why should we hire you?
Add your answer
Q2. What do you know about the company?
Add your answer