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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.
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Showing 2641–2670 of 9403 results
- DRWHardQuantitative ResearcherExpected Dart Score for a Bivariate Normal Throw with Ring Scoring
Calculate the expected score of a dart throw modeled by a zero-mean bivariate normal distribution with circular scoring rings, calibrated using a known hit probability inside the inner ring.
Statistics & MathOnsiteProbabilityBivariate NormalExpected Value - DRWHardQuantitative ResearcherExpected Rounds Until a Shopping-Cart Line Empties Under Random Transfers
Tests modeling discrete-time Markov chains, formulating hitting-time difference equations, and solving symmetric random walk absorption problems analytically.
Statistics & MathOnsiteMarkov ChainsProbabilityRandom Walk - DRWHardQuantitative ResearcherExpected Tosses Until HHT Given HHT Appears Before HTH
Calculate the probability that the coin sequence HHT appears before HTH in repeated fair tosses, and find the conditional expected number of tosses until termination given that HHT appears first.
Statistics & MathOnsiteprobabilitymarkov-chainsconditional-expectation - DRWHardQuantitative ResearcherExpected Winnings in a Random-Walk Money Collection Game on 45 Stones
Calculates a player's expected winnings in a random-walk money collection game on an odd-sized circle of stones using Gambler's Ruin and parity arguments.
Statistics & MathOnsiteprobabilityrandom-walkgamblers-ruin - DRWMediumMachine Learning EngineerExplain core ML and DL fundamentals
Explain core ML and DL fundamentals evaluates core ML concepts, assumptions, math intuition, training/evaluation trade-offs, and practical failure modes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Machine LearningOnline Assessment - DRWEasySoftware EngineerFewest Expenses to Defer to Year End So the Running Balance Never Goes Negative
Given a year's transactions in order, with income as positive values, expenses as negative values and a non-negative total, find the fewest expenses to move to the end of the year so the running balance never drops below zero. It tests reasoning over prefix sums for inputs of up to 100,000 transactions.
Coding & AlgorithmsTechnical Screen - DRWEasyData EngineerImplement Nested Transactions in an In-Memory Database
This problem tests your ability to manage state and scope using stacks and dictionaries to implement transaction isolation in a key-value store.
Coding & AlgorithmsOnline AssessmentHash MapStackTransactions - DRWMediumSoftware EngineerLargest Number From a 1-and-2 Digit String With Even Counts of Each Digit
Given a string of 1s and 2s that represents a positive integer, delete characters so the remaining counts of both digits are even, keeping the original order, and return the largest number that can remain. The problem tests careful case analysis of which digit occurrences to remove and efficient string handling for inputs up to 200,000 characters.
Coding & AlgorithmsHR Screen - DRWEasySoftware EngineerLongest Substring in Which Every Present Letter Occurs Equally Often
Given a string of lowercase letters, find the length of the longest substring in which every letter that appears occurs the same number of times. It tests substring enumeration with incremental frequency tracking and a precise definition of what counts as balanced.
Coding & AlgorithmsTechnical Screen - DRWHardSoftware EngineerMaximize a Digit Subsequence with Even Counts of Ones and Twos
Find the lexicographically/numerically largest subsequence of a string of '1's and '2's containing an even number of both digits in linear time.
Coding & AlgorithmsHR Screengreedystringssubsequences - DRWEasySoftware EngineerMinimize the Max-Min Gap of an Array After Changing Up to Three Elements
Given an integer array, you may change up to three elements to any values; return the smallest possible difference between the largest and smallest values afterward. It tests reasoning about which extreme values are worth changing and careful handling of short arrays.
Coding & AlgorithmsTechnical Screen - DRWHardQuantitative ResearcherPosterior Probability of a Two-Headed Coin After Three Heads
This question tests the application of Bayes' theorem, conditional likelihoods, and posterior probability updates given sequential binary observation data.
Statistics & MathOnsiteProbabilityBayes' TheoremQuantitative Research - DRWHardQuantitative ResearcherProbability the Two Strongest Teams Meet in a 16-Team Knockout Final
Calculate the probability that the two highest-ranked teams face each other in the championship match of a 16-team single-elimination tournament with probabilistic match outcomes.
Statistics & MathOnsiteprobabilitycombinatoricsconditioning - DRWMediumMachine Learning EngineerProcess CSV for portfolio returns and metrics
This question evaluates a candidate's competency in time-series data manipulation, financial return computation, portfolio analytics, numerical stability, modular software design (clear function boundaries and unit tests), and algorithmic complexity analysis within the Data Manipulation (SQL/Python) domain.
Data Manipulation (SQL/Python)Online Assessment - DRWMediumData ScientistSolve Markov and distribution expectation problems
This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Solve Markov and distribution expectation problems states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Statistics & MathOnsite - DRWMediumData ScientistSolve movie ratings, array, release scheduler
This question tests algorithmic problem-solving across three domains: greedy array optimization, tree-based data structure design, and efficient sequence merging. It evaluates practical coding ability and complexity analysis, commonly used in quantitative and data science interviews to assess how candidates identify inefficiencies and select the right data structure to improve performance.
Coding & AlgorithmsOnsite - DRWMediumSoftware EngineerSolve odd-string, digit swap, patient slot assignment
This multi-part problem evaluates string manipulation and parity/combinatorics for constructing odd-occurrence strings, greedy optimization and minimal-change reasoning for digit-swap distance minimization, and bipartite matching/assignment skills for patient slot allocation.
Coding & AlgorithmsOnline Assessment - DRWMediumSoftware EngineerSolve three algorithmic OA problems
This set evaluates algorithmic problem-solving skills including array manipulation and simulation for knockout tournament dynamics, graph traversal and constructive movement-sequence design on grids, and broader competencies in handling permutations, connectivity, and constraint-driven constructions.
Coding & AlgorithmsOnline Assessment - DRWMediumSoftware EngineerSolve three algorithmic OA tasks
Solve three algorithmic OA tasks evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - DRWMediumData ScientistSolve three algorithmic tasks in Python
This question evaluates proficiency in dynamic programming, range-query data structures (Fenwick/segment tree), sorting and two-pointer techniques, and algorithmic complexity analysis within the Coding & Algorithms domain for Python-based implementation.
Coding & AlgorithmsOnsite - DRWHardMachine Learning EngineerTrain LinearSVC to beat a hidden baseline
Train LinearSVC to beat a hidden baseline evaluates ML product requirements, data/labeling, modeling, serving architecture, evaluation, monitoring, and trade-offs in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
ML System DesignOnline Assessment - DRWEasyData EngineerValidate a Password Against Explicit Security Rules
This problem tests string manipulation, character set validation, and the ability to apply a sequence of conditional checks efficiently.
Coding & AlgorithmsOnline AssessmentStringsValidationIteration - Da Vinci TradingHardSoftware EngineerDesign an in-memory order matching engine
Matching engine design guide for an in-memory order book. Covers price-time priority, limit and market orders, matching rules, data-structure choices, edge cases, and how to explain tradeoffs in a system design interview.
System DesignOnline Assessment - DandyMediumMachine Learning EngineerWhy do transformers struggle with long context?
This question evaluates understanding of transformer architectures, attention mechanisms, and scalability trade-offs, assessing competencies in computational complexity, memory usage, and system-level performance implications.
Machine LearningHR Screen - Dark Alpha CapitalMediumSoftware EngineerMinimize Total Assignment Distance
This question evaluates competency in combinatorial optimization, assignment/matching problems, and reasoning about Manhattan distance cost metrics. Commonly asked to assess algorithmic reasoning about constrained assignments, search and complexity trade-offs, it belongs to the Coding & Algorithms domain and emphasizes practical application of algorithm design and implementation rather than purely conceptual theory.
Coding & AlgorithmsTechnical Screen - DatabricksMediumSoftware EngineerAdd Sliding-Window Get and Put Activity Metrics to a Key-Value Store
Design and implement an in-memory key-value store that tracks read and write throughput (operations per second) over configurable sliding windows.
Software Engineering FundamentalsOnsitedata-structuressliding-windowsystem-design - DatabricksMediumSoftware EngineerAnswer behavioral screen questions
Answer behavioral screen questions evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Behavioral & LeadershipHR Screen - DatabricksHardSoftware EngineerBuild a Constant-Time Snapshot Set Iterator
Design a mutable ordered integer set that supports constant-time snapshot iterator creation without copying the live dataset, preserving insertion order and handling elements that are removed and re-added.
Coding & AlgorithmsOnsiteData StructuresDesignLinked List - DatabricksMediumSoftware EngineerBuild a Durable Key-Value Cache
This question tests the ability to design a crash-recoverable key-value store by implementing a write-ahead log (WAL) to ensure data durability and system integrity after an unexpected failure.
Software Engineering FundamentalsOnsiteSystems DesignDurabilityLogging - DatabricksMediumSoftware EngineerCheck if CIDR is fully canceled by rules
This question evaluates understanding of IPv4 CIDR arithmetic, set operations on IP ranges (overlap detection and subtraction), and ordered rule semantics for allow/deny processing.
Coding & AlgorithmsTechnical Screen
DRW
Databricks