40+ Walmart Software Developer Interview Questions and Answers

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.

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.

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

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 possible to achieve that weight.

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.

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

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

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.

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.

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 element.

• For search operation, check if the element exists in...read more

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 house 2 as it gives maximum money without triggering alar...read more

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 so far.

• Return the maximum sum of an increasing subsequenc...read more

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.

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 accessed or updated.

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.

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.

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.

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.

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.

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

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'.

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.

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 polymorphism is achieved through method overriding, where a su...read more

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 provides a layer of abstraction between the Java code and ...read more

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 structures

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.

The ants will end up at the center of the triangle.

• The ants will move towards each other in a straight line.

• They will meet at the centroid of the triangle, which is the point where all three medians intersect.

• The centroid is located at two-thirds of the distance from each vertex to the midpoint of the opposite side.

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.

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 initial pages are loaded into memory. As the program prog...read more

The popular temple in my village is the Sri Ranganathaswamy Temple.

• Located in the heart of the village

• Dedicated to Lord Ranganatha

• Annual festivals and rituals attract devotees from neighboring villages

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

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.

My strength lies in my problem-solving skills and ability to learn quickly.

• Strong problem-solving skills

• Quick learner

• Adaptability to new technologies

• Ability to work well under pressure

Support from my team, access to resources, clear communication

• Support from my team helps me stay motivated and overcome challenges

• Access to resources such as training materials and tools enables me to perform my job effectively

• Clear communication ensures that I understand project requirements and expectations

I am proficient in 5 programming languages including Java, Python, C++, JavaScript, and SQL.

• Java

• Python

• C++

• JavaScript

• SQL

SCC stands for Source Code Control. It is a system used to manage and track changes to source code files.

• SCC helps developers collaborate on code by providing version control and tracking changes.

• Popular SCC tools include Git, SVN, and Mercurial.

• SCC allows developers to revert to previous versions of code, track changes made by team members, and merge code changes seamlessly.

• SCC helps in maintaining code integrity and ensuring that the latest version of code is always availab...read more

Develop a take home project involving fetching data from APIs

• Create a project that fetches data from a public API such as weather forecast or news articles

• Use libraries like Axios or Fetch API to make API calls

• Display the fetched data in a user-friendly interface

• Implement error handling for failed API calls

Intermediate refers to a level of proficiency or knowledge that falls between beginner and advanced.

• Intermediate level typically involves a deeper understanding of concepts and the ability to apply them in practical scenarios.

• Individuals at an intermediate level may have some experience in the field but still have room for growth and learning.

• Examples of intermediate skills include proficiency in a programming language, familiarity with common algorithms, and ability to work ...read more

System design on web applications involves planning and organizing the architecture, components, and interactions of the system.

• Understand the requirements and constraints of the web application

• Identify the components and modules needed for the system

• Design the architecture including front-end, back-end, and database

• Consider scalability, security, and performance

• Use appropriate technologies and frameworks

• Implement testing and monitoring strategies