100+ DE Shaw Interview Questions and Answers

To find the maximum length BST in a given binary tree.

• Traverse the tree in post-order fashion

• For each node, check if it satisfies the BST property

• If it does, calculate the size of the BST rooted at that node

• Keep track of the maximum size seen so far

The Large Hadron Collider is a particle accelerator used to study the smallest known particles and their interactions.

• The LHC is a circular tunnel located underground in Switzerland and France.

• It accelerates particles to nearly the speed of light and then collides them together.

• Scientists study the debris from these collisions to learn about the fundamental building blocks of the universe.

• The LHC has been used to discover the Higgs boson particle and search for evidence of da...read more

The problem involves finding the minimum steps to delete a substring comprising of same characters from a given string.

• Use dynamic programming to keep track of the minimum steps required to delete substrings.

• Iterate through the string and check for substrings with same characters.

• Update the DP array with the minimum steps required to delete the substring.

DE Shaw uses a combination of proprietary technology and algorithms for investments.

• DE Shaw utilizes advanced quantitative models and machine learning algorithms for investment decisions.

• They have developed their own trading platform and software tools to analyze market data and execute trades efficiently.

• The firm also leverages big data analytics and high-frequency trading strategies to gain a competitive edge in the market.

Algorithm to mirror a given Binary Tree

• Create a function to swap left and right child nodes of a given node

• Recursively call the function on left and right child nodes

• Base case: if node is null, return

• Call the function on the root node of the binary tree

Types of polymorphism in OOP include compile-time polymorphism (method overloading) and runtime polymorphism (method overriding).

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

• Runtime polymorphism is achieved through method overriding, where a subclass provides a specific implementation of a method that is already defined in its superclass.

• Polymorphism allows objects of different classes to ...read more

malloc() allocates memory but does not initialize it, while calloc() allocates and initializes memory to zero.

• malloc() is used to allocate a block of memory of specified size, while calloc() is used to allocate and initialize a block of memory to zero.

• malloc() returns a pointer to the allocated memory block, while calloc() returns a pointer to the allocated and initialized memory block.

• Example: int *arr1 = (int*)malloc(5 * sizeof(int)); // allocates memory for 5 integers

• Examp...read more

I am interested in Finance because of my passion for analyzing financial data and making informed investment decisions.

• I have always been fascinated by the world of finance and enjoy analyzing financial statements to understand the financial health of a company.

• I believe that finance plays a crucial role in driving economic growth and I am eager to contribute to this field.

• I have a strong analytical mindset and enjoy working with numbers and data to make informed financial de...read more

Compiler stages include preprocessing, compilation, assembly, and linking. Symbol table stores information about identifiers.

• Preprocessing stage handles directives like #include and #define

• Compilation stage translates source code to assembly language

• Assembly stage converts assembly code to machine code

• Linking stage combines object files and libraries into an executable

• Symbol table stores information about identifiers like variable names and function names

Access specifiers are keywords in object-oriented programming languages that determine the visibility and accessibility of class members.

• Access specifiers are used to restrict access to class members.

• There are three types of access specifiers: public, private, and protected.

• Public members can be accessed from anywhere in the program.

• Private members can only be accessed within the class.

• Protected members can be accessed within the class and its subclasses.

• Example: class MyClas...read more

Library functions are pre-written code that can be reused to perform common tasks.

• Library functions save time and effort by providing pre-written code.

• They are often included in programming languages or external libraries.

• Examples include functions for string manipulation, mathematical calculations, and file input/output.

• Library functions can be called from within a program to perform specific tasks.

• They can also be customized or extended to fit specific needs.

Recursion function is a function that calls itself until a base condition is met.

• Recursion is a technique used to solve problems by breaking them down into smaller sub-problems.

• It involves a function calling itself with a modified input until a base case is reached.

• Recursion can be used to solve problems such as factorial, Fibonacci series, and binary search.

• Recursion can be implemented using loops as well, but it may not always be efficient.

• Recursion can lead to stack overfl...read more

Serialization is the process of converting an object into a format that can be stored or transmitted.

• Serialization is used to save the state of an object and recreate it later.

• It is commonly used in network communication to transmit data between different systems.

• Examples of serialization formats include JSON, XML, and binary formats like Protocol Buffers.

• Deserialization is the opposite process of converting serialized data back into an object.

Explanation of memory sections: stack, heap, data

• Stack: stores function calls and local variables

• Heap: dynamically allocated memory

• Data: global and static variables

• Example: int x; //data, int *y = new int; //heap, void foo() { int z; } //stack

Documents required for foreign remittance include identification proof, proof of address, and purpose of remittance.

• Identification proof such as passport or driver's license

• Proof of address like utility bill or bank statement

• Purpose of remittance document like invoice or agreement

Java is platform independent due to its bytecode and JVM.

• Java code is compiled into bytecode, which can run on any platform with a Java Virtual Machine (JVM)

• JVM acts as an intermediary between the Java code and the underlying platform, ensuring portability

• Developers write code once and it can be executed on any platform that has a compatible JVM

• Examples: Windows, macOS, Linux all can run Java programs without any changes

Balancing of Btrees / AVL trees is important for efficient search and insertion operations.

• Btrees and AVL trees are self-balancing binary search trees.

• Balancing ensures that the height of the tree is minimized, leading to faster search and insertion operations.

• Btrees are used in databases while AVL trees are used in memory.

• Balancing is achieved by performing rotations and node splitting.

• AVL trees have a stricter balancing condition than Btrees, leading to higher overhead but ...read more

A torrent is a file-sharing method that allows users to download and upload files simultaneously. Seeders are users who have the complete file and upload it to others. Leechers are users who are downloading the file.

• Torrents are a peer-to-peer file-sharing method

• Users download and upload files simultaneously

• Seeders have the complete file and upload it to others

• Leechers are users who are downloading the file

• The more seeders, the faster the download

• Popular torrent clients inclu...read more

Blockchain is a decentralized digital ledger that records transactions in a secure and transparent manner.

• Blockchain is a distributed database that stores information across a network of computers

• It uses cryptography to secure and verify transactions

• It eliminates the need for intermediaries and reduces transaction costs

• Applications include cryptocurrency, supply chain management, and voting systems

Inheritance is a mechanism in object-oriented programming where a new class is created by inheriting properties of an existing class.

• Inheritance allows code reusability and saves time and effort in programming.

• The existing class is called the superclass or parent class, and the new class is called the subclass or child class.

• The subclass inherits all the properties and methods of the superclass and can also add its own unique properties and methods.

• For example, a class 'Anima...read more

A stack is a data structure that follows the Last-In-First-Out (LIFO) principle.

• Elements are added to the top of the stack and removed from the top.

• Common operations include push (add element) and pop (remove element).

• Stacks can be implemented using arrays or linked lists.

• Examples include the call stack in programming and the undo/redo feature in text editors.

Assembly is a low-level programming language that is used to write programs that can directly interact with computer hardware.

• Assembly language is specific to a particular computer architecture.

• It is a low-level language that is difficult to read and write.

• Assembly language programs are faster and more efficient than programs written in high-level languages.

• Examples of assembly language include x86, ARM, and MIPS.

• Assembly language is often used for system-level programming, d...read more

A daemon process is a background process that runs continuously to perform system tasks.

• Daemon processes do not have a controlling terminal.

• They typically run in the background and perform tasks such as managing hardware devices, network services, or system maintenance.

• Examples of daemon processes include cron, sshd, and apache.

• Daemon processes are often started during system boot and run until the system is shut down.

A C program gets executed by first being compiled into machine code and then run by the operating system.

• C program is written in a text editor and saved with a .c extension.

• The program is then compiled using a compiler like GCC into machine code.

• The resulting executable file is loaded into memory by the operating system and executed.

• The program's instructions are carried out sequentially by the CPU.

• Once the program finishes, it returns an exit status to the operating system.

Banker's algorithm is a deadlock avoidance algorithm used in operating systems.

• It is used to avoid deadlock in a multi-process system.

• It works by checking if a request for resources will leave the system in a safe state.

• It uses a matrix to represent the current state of the system and the maximum resources each process can request.

• If the request can be granted without leaving the system in an unsafe state, it is granted.

• If not, the process must wait until the resources become...read more

Higgs boson is a subatomic particle that gives mass to other particles.

• Higgs boson was first theorized in the 1960s by physicist Peter Higgs.

• It was finally discovered in 2012 by the Large Hadron Collider.

• The discovery of the Higgs boson confirmed the Standard Model of particle physics.

• The Higgs boson is sometimes referred to as the 'God particle'.

Answering OOP Java design problems

• Identify the problem domain and create a class hierarchy

• Use encapsulation to hide implementation details

• Apply inheritance to reuse code and create subtypes

• Implement polymorphism to allow objects to take on multiple forms

• Avoid tight coupling and favor composition over inheritance

• Use design patterns to solve common problems

• Consider SOLID principles for maintainable code

A virtual function is a function in a base class that is declared using the keyword 'virtual' and can be overridden by a function with the same signature in a derived class.

• Virtual functions allow for dynamic polymorphism in object-oriented programming.

• They are used to achieve runtime binding and enable the implementation of the function to be determined during runtime.

• Example: virtual void display() = 0; in a base class and void display() override in a derived class.

A function to determine the endianess of a machine

• Create a variable with value 1

• Cast the variable to a byte array

• If the first byte is 1, the machine is little endian, else big endian

IRR and NPV are key financial metrics used to evaluate the profitability of an investment.

• IRR (Internal Rate of Return) is the discount rate that makes the net present value (NPV) of all cash flows from a particular investment equal to zero.

• NPV (Net Present Value) is the difference between the present value of cash inflows and outflows over a specific period of time.

• Both IRR and NPV help investors assess the potential return and risk associated with an investment.

• Investments ...read more

Intersection of two lists in Java

• Convert lists to sets and use retainAll() method

• Iterate through one list and check if element is present in other list

• Use Java 8 streams and filter() method

Heap and stack are two memory allocation areas in a program.

• Heap is used for dynamic memory allocation and is managed by the programmer.

• Stack is used for static memory allocation and is managed by the system.

• Heap memory is allocated using 'new' keyword in C++ and 'malloc' function in C.

• Stack memory is allocated automatically for local variables and function calls.

• Heap memory is not automatically deallocated and can cause memory leaks if not managed properly.

• Stack memory is au...read more

The politics of freebies is a controversial topic with varying opinions.

• Freebies can be used as a marketing strategy to attract customers

• Some argue that freebies create a culture of entitlement and dependency

• Politicians often use freebies as a way to gain votes

• Freebies can have a negative impact on the economy and government finances

• Examples of freebies include free healthcare, education, and basic income

Five file compression extensions

• .zip

• .rar

• .7z

• .tar.gz

• .tar.bz2

OOP concepts in Java

• Encapsulation - hiding implementation details

• Inheritance - creating new classes from existing ones

• Polymorphism - ability of objects to take on multiple forms

• Abstraction - focusing on essential features and ignoring the rest

• Example: A Car class can inherit from a Vehicle class

• Example: A Dog class can have a bark() method that overrides the Animal class's makeSound() method

• Example: A Shape class can have an abstract method called calculateArea()

• Example: A Ba...read more

Banker's Algorithm is a resource allocation and deadlock avoidance algorithm used in operating systems.

• Used to avoid deadlock in a system by ensuring that resources are allocated safely.

• Works by keeping track of available resources and the maximum resources each process can request.

• If a request for resources puts the system in an unsafe state, it is denied.

• Example: Process A needs 3 instances of resource X, but only 2 are available, so the request is denied.

Inheritance is a mechanism in object-oriented programming where a class inherits properties and behaviors from another class.

• Inheritance allows for code reuse and promotes the concept of hierarchy.

• The class that inherits properties and behaviors is called the derived class or subclass.

• The class from which properties and behaviors are inherited is called the base class or superclass.

• Constructors in a class are special methods used to initialize objects of that class.

• Inheritanc...read more

BIOS stands for Basic Input/Output System.

• BIOS is a firmware that initializes hardware during the boot process.

• It provides a low-level interface between the hardware and the operating system.

• BIOS settings can be accessed and modified through a setup utility.

• BIOS can be updated to fix bugs or add new features.

• Examples of BIOS manufacturers include AMI, Phoenix, and Award.

A real world application of linked lists is in music playlists.

• Linked lists can be used to create playlists where each song is a node pointing to the next song.

• This allows for easy insertion and deletion of songs without having to shift the entire playlist.

• Popular music streaming services like Spotify and Apple Music use linked lists to manage playlists.

• Linked lists can also be used in video playlists, where each video is a node pointing to the next video.

Ensure scalability in system design by using horizontal scaling, load balancing, caching, and microservices architecture.

• Implement horizontal scaling to add more servers to handle increased load.

• Use load balancing to distribute incoming traffic across multiple servers.

• Utilize caching to store frequently accessed data and reduce database load.

• Adopt microservices architecture to break down the system into smaller, independent services that can be scaled individually.

Group list of strings as anagrams and return the list.

• Create a hashmap to store sorted strings as keys and list of anagrams as values

• Iterate through the list of strings, sort each string and add it to the corresponding list in the hashmap

• Return the values of the hashmap as the grouped anagrams

LED, LCD, and Plasma are types of televisions that differ in their display technology.

• LED TVs use light-emitting diodes to backlight the display.

• LCD TVs use liquid crystal displays to create images.

• Plasma TVs use tiny cells filled with gas to create images.

• LED TVs are more energy-efficient and have better contrast than LCD TVs.

• LCD TVs are thinner and lighter than Plasma TVs.

• Plasma TVs have better color accuracy and wider viewing angles than LCD TVs.

• LED TVs are the most popula...read more

Test scenarios for testing WhatsApp application

• Verify sending a text message

• Test sending multimedia files (images, videos)

• Check group chat functionality

• Test voice and video call features

• Verify message encryption and security measures

HTTP is unsecured while HTTPS is secured with SSL/TLS encryption.

• HTTP stands for Hypertext Transfer Protocol while HTTPS stands for Hypertext Transfer Protocol Secure.

• HTTP operates on port 80 while HTTPS operates on port 443.

• HTTP is vulnerable to attacks like man-in-the-middle and eavesdropping while HTTPS is secure against such attacks.

• HTTPS uses SSL/TLS encryption to protect the data transmitted between the client and server.

• HTTPS is indicated by a padlock icon in the brows...read more

Some sources of HR sourcing include job boards, social media, employee referrals, recruitment agencies, and career fairs.

• Job boards such as Indeed, Glassdoor, and LinkedIn are common sources for posting job openings.

• Social media platforms like Facebook, Twitter, and Instagram can be used to attract potential candidates.

• Employee referrals involve current employees recommending candidates for open positions.

• Recruitment agencies specialize in finding and screening candidates for...read more

Use a combination of hash table and linked list to achieve O(1) operations for a Hash Map.

• Use a hash table to store key-value pairs and a linked list to handle collisions.

• Implement a hash function to map keys to indices in the hash table.

• For each key, calculate the hash value and store the corresponding value in the hash table at that index.

• To handle collisions, use separate chaining with linked lists at each index of the hash table.

• When searching for a key, calculate the has...read more

TDS stands for Tax Deducted at Source, a system where tax is deducted by the payer at the time of making payment.

• TDS is a system introduced by the Income Tax Department of India to collect tax at the source from where an individual's income is generated.

• It is applicable to various payments such as salary, interest, commission, rent, etc.

• The deducted TDS amount is then deposited to the government by the deductor.

• TDS rates vary based on the type of payment and the income slab o...read more

GST on reverse charge is a mechanism where the recipient of the goods/services is liable to pay the tax instead of the supplier.

• Under reverse charge mechanism, the recipient of the goods/services is responsible for paying the GST instead of the supplier.

• It is applicable in certain cases like import of services, specified goods/services, etc.

• The recipient needs to self-assess and pay the tax directly to the government.

• Input tax credit can be claimed by the recipient for the ta...read more

Calloc initializes memory with zero while malloc does not.

• Calloc allocates memory and initializes it with zero

• Malloc allocates memory but does not initialize it

• Calloc is useful for allocating memory for arrays

• Malloc is useful for allocating memory for single variables

Thrashing occurs when a computer's performance suffers due to excessive swapping of data between RAM and virtual memory.

• Thrashing happens when the system is overburdened with too many processes and there is not enough physical memory to handle them.

• The operating system starts swapping data between RAM and virtual memory, which slows down the system.

• This can lead to a vicious cycle where the system spends more time swapping than executing processes, causing further slowdowns.

• T...read more

Use dynamic programming to find the longest strictly increasing path in a matrix.

• Use dynamic programming to keep track of the longest increasing path ending at each cell.

• Start from each cell and recursively explore all 4 directions to find the longest increasing path.

• Update the length of the longest increasing path at each cell based on the maximum length from its neighbors.

Implement LFU cache using OOPs concepts

• Create a class for LFU cache with methods like get, put, and remove

• Use a hashmap to store key-value pairs and a hashmap to store frequency of each key

• Implement a doubly linked list to store keys with the same frequency

Page Replacement Algorithm is used to decide which page to remove from memory when new page is to be loaded.

• It is used in operating systems to manage memory.

• It is based on the principle of locality of reference.

• Examples include FIFO, LRU, Optimal, etc.

To find the middle element of a LinkedList, use two pointers - one moving at double the speed of the other.

• Initialize two pointers, slow and fast, at the head of the LinkedList.

• Move the slow pointer by one step and the fast pointer by two steps until the fast pointer reaches the end of the LinkedList.

• The element pointed to by the slow pointer at this point will be the middle element.

Stack and queue can be implemented using arrays or linked lists. Stack follows LIFO while queue follows FIFO.

• Stack can be implemented using arrays with push and pop operations.

• Queue can be implemented using arrays with enqueue and dequeue operations.

• Both stack and queue can also be implemented using linked lists for dynamic size.

• Example: Implementing a stack using an array in C++

• Example: Implementing a queue using a linked list in Java

Indexing mechanism in DBMS is used to improve the performance of database queries by reducing the time taken to search for data.

• Indexes are created on one or more columns of a table

• They are used to speed up the search for data by creating a separate data structure that allows for faster access to the data

• Indexes can be created using different algorithms such as B-tree, hash, and bitmap

• Indexes can be clustered or non-clustered

• Clustered indexes determine the physical order of d...read more

Inorder traversal is a way of visiting each node in a binary tree in a specific order.

• Start at the leftmost node and traverse the left subtree recursively.

• Visit the current node.

• Traverse the right subtree recursively.

• Repeat until all nodes have been visited.

• Inorder traversal is commonly used to print the nodes of a binary search tree in sorted order.

P2P network is a decentralized network where peers communicate and share resources directly without a central server.

• P2P stands for peer-to-peer.

• It allows for direct communication and sharing between peers without the need for a central server.

• Examples include BitTorrent, Bitcoin, and Skype.

• P2P networks are often used for file sharing, messaging, and cryptocurrency transactions.

Projects and queries involve understanding and working on various software projects and related inquiries.

• Projects involve developing, testing, and maintaining software applications.

• Queries may include troubleshooting issues, optimizing performance, and implementing new features.

• Examples of queries include debugging a software bug, improving code efficiency, and integrating a new API.

J.E stands for Journal Entry, which is a record of financial transactions in a company's accounting system.

• J.E is used to record all financial transactions in a company's accounting system

• It includes details such as date, accounts involved, amounts, and descriptions

• J.E is used to create financial statements such as the balance sheet and income statement

• It helps in identifying errors and discrepancies in the accounting system

• Example: A company records a sale of $1000. The J.E ...read more

Design a distributed trading system platform

• Utilize microservices architecture for scalability and fault tolerance

• Implement message queues for asynchronous communication between components

• Use distributed databases for data storage and retrieval

• Implement load balancing and auto-scaling for handling varying loads

• Ensure security measures such as encryption and authentication are in place

To burn a node in a binary tree, we mark the node as burned and then recursively burn its left and right children.

• Mark the current node as burned

• Recursively burn the left child

• Recursively burn the right child

Find the maximum product sub-array in an array of integers.

• Iterate through the array and keep track of the maximum product ending at each index.

• Also keep track of the minimum product ending at each index, as negative numbers can change the sign of the product.

• Update the maximum product by taking the maximum of the current element, current element times the maximum product ending at previous index, and current element times the minimum product ending at previous index.

Finding median of two sorted arrays

• Merge the two arrays and find the median

• Use binary search to find the median in O(log(min(m,n))) time

• Divide both arrays into two parts and compare the medians to discard half of the elements

BST (Binary Search Tree) is a data structure where each node has at most two children, with left child being less than parent and right child being greater.

• BST is used for efficient searching, insertion, and deletion of elements.

• In-order traversal of BST gives elements in sorted order.

• Example: Inserting elements 5, 3, 8, 1, 4 into a BST would result in a tree with root 5, left child 3, right child 8, and left child of 3 having children 1 and 4.

Depreciation reduces the value of assets over time, impacting financial statements.

• Depreciation is a non-cash expense that reduces the value of assets on the balance sheet.

• It is recorded on the income statement and reduces net income.

• Depreciation can impact financial ratios such as return on assets and debt-to-equity.

• Different methods of depreciation can be used, such as straight-line or accelerated.

• Depreciation can also impact taxes, as it is a deductible expense.

• Depreciatio...read more

A lambda function is an anonymous function that can be used to write concise and reusable code.

• Lambda functions are often used in functional programming languages.

• They can be used as arguments to higher-order functions.

• Lambda functions can be written inline without a separate function definition.

• They are commonly used for tasks that require a short and simple piece of code.

• Lambda functions can be used in various programming languages like Python, JavaScript, and Java.

Fundamentals of analysis in RE involve understanding requirements, identifying stakeholders, and creating models.

• Understand the requirements of the project

• Identify the stakeholders and their needs

• Create models to represent the system

• Analyze the models to ensure they meet the requirements

• Iterate the process as necessary

Recursively iterate through an array of strings

• Use a base case to stop the recursion

• Pass a smaller portion of the array in each recursive call

• Concatenate or manipulate the strings as needed

OOPS concepts are the foundation of object-oriented programming, including inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation details and showing only the necessary features.

To create a pointer array of strings:

• Declare a pointer array variable with the desired size

• Allocate memory for each string in the array using malloc

• Assign the memory address of each string to the corresponding array element

Code to reverse a binary search tree (BST)

• Traverse the BST in post-order

• Swap the left and right child of each node

• Return the root node of the reversed BST

Golden rules of accounting are basic principles that guide the process of recording financial transactions.

• The three golden rules of accounting are: 1. Debit the receiver, Credit the giver 2. Debit what comes in, Credit what goes out 3. Debit expenses and losses, Credit income and gains

• These rules help maintain the balance in the accounting equation: Assets = Liabilities + Equity

• For example, when a company receives cash from a customer, it would debit the cash account (increa...read more

Design a zepto delivery system for efficient and fast delivery of small packages.

• Utilize drones for quick and efficient delivery

• Implement a centralized hub for package sorting and distribution

• Use GPS tracking for real-time package monitoring

• Optimize routes for faster delivery times

• Ensure secure and reliable delivery process

Chemicals are substances with specific properties used in various industries for different purposes.

• Chemicals are used in manufacturing processes to create products such as plastics, pharmaceuticals, and fertilizers.

• They are also used in cleaning products, agriculture, and construction materials.

• Some common chemicals include sodium chloride (table salt), sulfuric acid, and ammonia.

• Chemicals can be hazardous if not handled properly, requiring safety precautions and proper disp...read more

Deep cleaning procedure involves thorough cleaning of all surfaces and areas to remove dirt, grime, and bacteria.

• Start by decluttering the area to be cleaned

• Use appropriate cleaning products and tools for different surfaces

• Focus on high-touch areas like doorknobs, light switches, and countertops

• Pay attention to detail, including corners and crevices

• Allow sufficient time for cleaning and disinfection to ensure thoroughness

The profile is a comprehensive overview of an individual's skills, experience, education, and achievements.

• Includes information on professional background, education, skills, and accomplishments

• Highlights key achievements and career milestones

• May also include personal interests and hobbies to provide a well-rounded view of the individual

• Used for job applications, networking, and professional branding