practice a little every day, paws crossed ♡
Software Engineer 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 1–24 of 24 results
- CiscoHardSoftware EngineerFormalize a Minimum-Trip Transport Puzzle with Horses and Ladders
Model a horses-and-ladders transport puzzle by clarifying legal moves, tracking resource state, and proving a minimum-trip plan is optimal.
Statistics & MathTechnical Screen - CitadelMediumSoftware EngineerChoose 200 of a Million Records to Label, Improving on Uniform Random Sampling
Tests the ability to define data informativeness under extreme budget constraints (selecting 200 out of 1,000,000 records) and design a scalable, one-shot sampling strategy that outperforms uniform random sampling in coverage and diversity.
Statistics & MathTechnical ScreenActive LearningSamplingClustering - CitadelHardSoftware EngineerCompute Statistics from a Frequency Array
Compute count, minimum, maximum, mean, median, mode, and population standard deviation directly from a 256-bin frequency array. Use weighted moments and cumulative ranks without expanding samples, define empty-data behavior and ties, and address overflow and numerical precision.
Statistics & MathTechnical Screen - DeshawHardSoftware EngineerCompare Fixed and Variable Train Gaps Without a Timetable
Compare two train services for a commuter who arrives without consulting a timetable. Explain the assumptions and derivation clearly, check edge cases, and show how the result changes when those assumptions no longer hold.
Statistics & MathTechnical Screen - 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 - Jane StreetHardSoftware EngineerOptimal Stopping with Square-Number Ruin
Analyze an optimal stopping game where a player rolls a fair six-sided die to accumulate points but busts if the running sum hits a positive perfect square. Tests dynamic programming, renewal theory intuition, and rigorous edge-case analysis under uncertain stopping boundaries.
Statistics & MathTechnical Screenprobabilityoptimal-stoppingdynamic-programming - Jane StreetHardSoftware EngineerOptimize a Two-Box Place-or-Take Game
Analyze and optimize a 100-turn, two-box stochastic game with capacity constraints and opaque states. Derive the optimal decision policy, examine boundary/edge cases, and evaluate how the strategy changes when core assumptions are relaxed.
Statistics & MathTechnical ScreenProbabilityDynamic ProgrammingMarkov Decision Process - Jump TradingEasySoftware EngineerFind the Largest Equivalence Class of Fractions
This problem tests your ability to handle numerical equivalence using canonical representations to avoid floating-point precision issues.
Statistics & MathTechnical ScreenMathHash MapNumber Theory - MercorHardSoftware EngineerFind the Probability That One Shop Supplies the Top Two Coffees
Calculate the probability that the top-ranked coffees in a blind competition come from the same shop under an exchangeable, tie-free ranking model.
Statistics & MathTechnical Screenprobabilitycombinatoricsexchangeability - MercorMediumSoftware EngineerProbability Both Drinks from One Coffee Shop Outscore Both Drinks from Another
A probability brainteaser: two drinks are ordered at each of two coffee shops and every drink receives a quality score, and you must find the probability that both drinks from the first shop outscore both drinks from the second. It tests symmetry arguments, counting rankings, and stating independence and tie assumptions.
Statistics & MathTechnical Screen - MercorMediumSoftware EngineerProbability That One Customer's Two Coffees Beat Another's Two
A probability puzzle in which two customers each buy two cups of coffee of random quality, and you find the chance that one customer's cups are better than the other's. It tests clarifying what better means, using symmetry over rankings, checking the result a second way, and reasoning about ties and correlated cups.
Statistics & MathTechnical Screen - MercorMediumSoftware EngineerReason About Coffee-Quality Comparison Probabilities
Calculate conditional comparison probabilities for coffee quality scores under continuous and discrete distributions, accounting for ties and sample permutations.
Statistics & MathTechnical Screenprobabilitycombinatoricsstatistics - MetaMediumSoftware EngineerDerive max distinct frequencies for n items
The question evaluates combinatorial reasoning, discrete mathematics, and constructive extremal analysis by asking for the maximum number of distinct frequency counts in an array and a matching construction.
Statistics & MathTechnical Screen - MetaMediumSoftware EngineerMeasure Forty-Five Minutes with Two Unevenly Burning Ropes
Measure exactly 45 minutes using two ropes that each burn for 60 minutes but at unpredictable rates. The reasoning must rely only on lighting rope ends and observing completion events, never on assuming that half a rope represents half the time.
Statistics & MathTechnical Screen - OptiverHardSoftware EngineerAnalyze an Unfair-Coin Bankroll Game
This problem tests probability theory and expected value calculations in the context of a game with an unfair coin and a bankroll constraint.
Statistics & MathTechnical ScreenProbabilityExpected ValueRecurrence Relations - OptiverHardSoftware EngineerCalculate the Probability That Two Dice Sum to Seven
This question tests fundamental understanding of discrete probability, combinatorics, and the impact of conditional dependencies on outcomes.
Statistics & MathTechnical ScreenProbabilityCombinatoricsStatistics - OptiverMediumSoftware EngineerCompute expectations, conditionals, odds, and distributions
This question evaluates proficiency in fundamental probability and statistics concepts — including expected value and variance, conditional probability, discrete arrival modeling, betting odds and the Kelly criterion, and combinatorics for draws without replacement — and is categorized under Statistics & Math.
Statistics & MathTechnical Screen - OptiverMediumSoftware EngineerDemonstrate task switching and memory strategies
This question evaluates task-switching ability, working-memory management, interference control, and error-recovery strategies—core executive functions involved in rapid stimulus–response mappings.
Statistics & MathTechnical Screen - OptiverHardSoftware EngineerFind the Color Probability After Discarding Cards
This problem tests your understanding of conditional probability, combinatorics, and how dependent events (sampling without replacement) impact statistical expectations.
Statistics & MathTechnical ScreenProbabilityCombinatoricsStatistics - OptiverHardSoftware EngineerFind the Probability That the Three Smallest Dice Sum to Three
This problem tests combinatorics and probability theory by requiring the derivation of the exact probability that the three smallest values of four independent dice rolls sum to exactly three.
Statistics & MathTechnical ScreenProbabilityCombinatoricsStatistics - SnapchatMediumSoftware EngineerExplain median vs mean for L1/L2
This question evaluates understanding of central tendency and loss functions—specifically the roles of median and mean under L1 (absolute) and L2 (squared) norms—and the geometric extension of these concepts to two-dimensional data.
Statistics & MathTechnical Screen - SquarepointMediumSoftware EngineerFind the Correlation Between Two Die-Face Counts
A fair six-sided die is rolled independently `n` times, where `n` is a fixed positive integer. Explain the assumptions and derivation clearly, check edge cases, and show how the result changes when those assumptions no longer hold.
Statistics & MathTechnical Screen - TekionMediumSoftware EngineerCount Open Lockers After 100 Rounds
This problem tests mathematical reasoning and pattern recognition, specifically the relationship between integer divisors and toggling operations.
Statistics & MathTechnical ScreenMathematicsNumber TheoryPattern Recognition - TekionMediumSoftware EngineerFind an Optimal Strategy for an Even-Row Coin Game
Analyze optimal play in an even-row coin game, using position parity and game values to distinguish a guaranteed tie from a strict first-player win.
Statistics & MathTechnical Screen
Citadel
Hudson River Trading
Jane Street
Mercor
Meta
Optiver
Snapchat
Squarepoint