practice a little every day, paws crossed ♡
Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
- 9403
- Questions
- 546
- Companies
- 11
- Topics
- 8
- Languages
Showing 4051–4080 of 9403 results
- Hudson River TradingMediumSoftware EngineerApproach verbose data-structure design
This question evaluates a candidate's ability to design and implement complex data structures, testing algorithmic reasoning, time/space complexity analysis, state modeling, and organization of code and tests.
Coding & AlgorithmsTechnical Screen - Hudson River TradingEasySoftware EngineerBall Position in a Tilting Maze After Timed Tilt Events
Live coding simulation problem: a ball sits in a grid maze on a board that can tilt up, down, left or right or lie flat, and timed events change the tilt. Return the ball's cell at an end time that can be very large. It tests precise timing rules, wall handling and movement code that scales to long time spans.
Coding & AlgorithmsTechnical Screen - Hudson River TradingHardSoftware EngineerBuild a Heart Disease Baseline
This question evaluates proficiency in applied machine learning workflows, including data inspection and cleaning, exploratory data analysis, feature engineering, baseline binary classification modeling, and evaluation using Python libraries like pandas and seaborn.
Machine LearningOnsite - Hudson River TradingHardSoftware EngineerC++ Fundamentals: Memory, Compilation, and Containers
Tests deep C++ expertise in zero-allocation data structures, cache-line alignment, manual object lifecycle management via placement new, and the compilation/inlining implications of template-based designs.
Software Engineering FundamentalsTechnical ScreenC++Memory ManagementData Structures - Hudson River TradingMediumSoftware EngineerCalculate Completion Time for a Single-Server Reactor Queue
Simulate a single-threaded reactor queue with a bounded buffer to compute the completion timestamp or drop status for each incoming task.
Coding & AlgorithmsTechnical ScreenQueueSimulationArrays - Hudson River TradingEasySoftware EngineerCheck Root-To-Leaf Target Sums In A Binary Tree
This question tests your ability to traverse a binary tree using depth-first search (DFS) or breadth-first search (BFS) while tracking path accumulators and accurately identifying valid leaf nodes.
Coding & AlgorithmsTechnical ScreenBinary TreeDFSRecursion - Hudson River TradingMediumSoftware EngineerChoose Mean or Median for Trading Profit Metrics
This problem tests your understanding of statistical measures of central tendency, specifically how different distributions affect the choice between mean and median in high-frequency trading scenarios.
Statistics & MathTechnical ScreenStatisticsFinanceData Analysis - Hudson River TradingMediumSoftware EngineerCompare C++ Pointers and References
Tests in-depth understanding of C++ raw pointers versus references, their language semantics, memory representations, and how to apply them to design safe, idiomatic, zero-cost APIs.
Software Engineering FundamentalsTechnical Screencppsystemsapi-design - Hudson River TradingMediumSoftware EngineerCompare C++ Virtual Dispatch with CRTP
Compare C++ virtual dispatch with CRTP across runtime flexibility, object layout, separate compilation, heterogeneous collections, inlining, code size, diagnostics, ABI stability, and measured performance.
Software Engineering FundamentalsOnsite - Hudson River TradingMediumData ScientistCompare Mean and Median for a Distribution with a Point Mass
This question tests the theoretical and empirical comparison between the sample mean and sample median on a mixture distribution containing a discrete point mass and a Gaussian component.
Statistics & MathTechnical Screenstatisticsprobabilityestimation - Hudson River TradingMediumSoftware EngineerCompare Multithreading and Multiprocessing
This question tests your understanding of concurrency primitives, operating system process models, memory isolation, context switching overheads, and the architectural trade-offs between threads and processes in low-latency systems.
Software Engineering FundamentalsTechnical Screenconcurrencyoperating-systemsmultithreading - Hudson River TradingMediumSite Reliability EngineerCompare Python Generators, Decorators, and Context Managers
Tests understanding of Python's execution timing, protocol methods, and resource cleanup across generators, decorators, and context managers, culminating in a robust lazy stream processor.
Software Engineering FundamentalsTechnical ScreenPythonResource ManagementDecorators - Hudson River TradingMediumSoftware EngineerCount Digit-Reversal Equivalent Pairs
Count pairs of indices in an integer array whose values share the same canonical digit-reversal form.
Coding & AlgorithmsTechnical ScreenHash TableMathString - Hudson River TradingMediumSoftware EngineerCount Length-3 Chat Substrings with a Vowel
Count the number of distinct length-3 alphabetical substrings in a chat message that contain at least one vowel.
Coding & AlgorithmsTechnical Screenstringsliding-windowhash-set - Hudson River TradingMediumSoftware EngineerCount Matrix Cells Whose Row and Column Neighbors Match
This problem tests your ability to efficiently traverse a grid while implementing conditional neighborhood logic and handling boundary constraints.
Software Engineering FundamentalsTechnical ScreenArraysMatrixGrid - Hudson River TradingEasyMachine Learning EngineerCount People Reaching the Boundary
This question evaluates algorithmic simulation and event-driven modeling skills, specifically handling discrete versus continuous time, visibility constraints relative to a stationary watcher that changes facing direction, and boundary conditions for state transitions.
Coding & AlgorithmsOnsite - Hudson River TradingMediumData ScientistCount Smaller Numbers with Only Zero and One in Base Four
Count the number of positive integers strictly less than n whose base-4 representation consists only of the digits 0 and 1.
Coding & AlgorithmsOnline AssessmentMathBit ManipulationDigit DP - Hudson River TradingMediumData ScientistCount inversions in a permutation
This question evaluates understanding of inversion counting in permutations, testing algorithmic problem-solving, complexity analysis, and data-structure reasoning about pairwise order relations.
Coding & AlgorithmsTechnical Screen - Hudson River TradingEasySoftware EngineerCount players reaching end with moving watchers
This problem tests your ability to model state transitions over discrete time steps and efficiently track interval coverage using sorting and sweep-line logic.
Coding & AlgorithmsTechnical ScreenSimulationGeometryOptimization - Hudson River TradingMediumData ScientistDerive expected inversions and mean distribution
This problem tests your understanding of linearity of expectation and variance properties applied to permutation statistics, as well as the ability to design a simulation to verify analytical derivations.
Machine LearningTechnical ScreenProbabilityStatisticsExpectation - Hudson River TradingMediumSoftware EngineerDesign a Fixed-Size Memory Allocator with Correct Alignment
Design a slab-backed fixed-size allocator with constant-time free-list operations, correct stride and alignment, separate object lifetime, corruption defenses, concurrency choices, and efficient handling of nine-byte payloads.
Software Engineering FundamentalsOnsite - Hudson River TradingHardSoftware EngineerDesign an Indexable Deque with O(1) Access
Tests understanding of low-level data structure design, memory layout, and trade-offs required to build a double-ended queue supporting strict O(1) random indexing and amortized O(1) push/pop operations.
Software Engineering FundamentalsTechnical ScreenData StructuresArraysSystem Fundamentals - Hudson River TradingMediumSoftware EngineerDesign comprehensive OA test cases
This question assesses a software engineer's practical test design skills under time pressure, specifically the ability to partition input spaces into equivalence classes and boundary cases for algorithm and data structure problems. It evaluates systematic testing methodology, including oracle-based verification strategies and defensible stopping rules — competencies commonly probed in online assessments and technical interviews to gauge engineering rigor.
Behavioral & LeadershipTechnical Screen - Hudson River TradingMediumSoftware EngineerDetermine Whether Two Integers Sum to a Target
This problem tests proficiency with hash sets to achieve linear time complexity and emphasizes defensive programming practices like input validation and immutability.
Coding & AlgorithmsTechnical ScreenHash SetArraysTwo Pointers - Hudson River TradingMediumSoftware EngineerDiagnose I/O, Memory, and CPU Constraints
Tests your ability to systematically diagnose, measure, and resolve CPU, memory, and I/O bottlenecks in high-throughput, low-latency systems.
Software Engineering FundamentalsTechnical ScreenSystemsPerformance OptimizationOperating Systems - Hudson River TradingHardSoftware EngineerExplain C++ Inline, Segfaults, Virtual Memory, and std::string Internals
Tests deep understanding of low-level systems and modern C++ fundamentals, focusing on compiler inlining mechanics, virtual memory paging, segmentation fault root causes, and standard library string memory layouts.
Software Engineering FundamentalsTechnical ScreenC++Virtual MemoryOperating Systems - Hudson River TradingHardSoftware EngineerExplain Large Memory Allocation, Swap, and C++ Inline Trade-offs
Tests deep understanding of OS virtual memory management, demand paging and swap mechanics, and low-latency C++ compiler optimizations centered around inlining and instruction cache trade-offs.
Software Engineering FundamentalsTechnical Screenc++operating-systemsvirtual-memory - Hudson River TradingHardSoftware EngineerExplain Python and React performance fundamentals
This question evaluates knowledge of Python resource management (context managers and the with statement), React rendering and optimization concepts (hooks, memoization, and frontend performance), and on-call debugging and incident triage skills.
Software Engineering FundamentalsTechnical Screen - Hudson River TradingMediumSoftware EngineerExplain Virtual Memory, MMUs, and TLBs
Trace a virtual-memory load through TLB lookup, page-table walking, MMU permission checks, cache and physical access, page-fault handling, context switches, huge pages, and cross-core shootdowns.
Software Engineering FundamentalsOnsite - Hudson River TradingMediumSite Reliability EngineerExplain Why du and df Report Different Disk Usage
This question tests your understanding of Linux filesystem internals, specifically how kernel-level storage reporting differs from user-space directory traversal.
Software Engineering FundamentalsTechnical ScreenLinuxFilesystemSRE
Hudson River Trading