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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 751–780 of 781 results
- VisaMediumSoftware EngineerCount Space-Separated Words Made Only of Letters and Basic Punctuation
A string-processing coding problem: split a sentence on spaces and count the tokens that contain only English letters and the punctuation marks comma, period, question mark and exclamation mark. It tests careful tokenization with repeated spaces and exact character-class rules.
Coding & AlgorithmsOnline Assessment - VisaMediumSoftware Engineer IDesign E-Commerce Tables and Indexes for Recent-Spend Queries
This question tests database schema normalization, data integrity in e-commerce transactions, and the ability to optimize SQL queries using indexing strategies.
System DesignOnline AssessmentSQLDatabase DesignIndexing - VisaMediumSoftware EngineerEarliest K-Minute Meeting Start from Text Schedules with Inclusive Busy Times
A scheduling coding problem: given everyone's busy intervals as text entries with inclusive minute times, find the earliest start for a meeting of k minutes after the day's first busy minute, or report that none exists. It tests time parsing, merging overlapping intervals and off-by-one boundaries.
Coding & AlgorithmsOnline Assessment - VisaMediumSoftware EngineerFind the Minimum Edge Score on a Path Between Two Cities
This problem tests the ability to optimize for the bottleneck edge in a path rather than the total path cost, typically solvable using a modified Dijkstra's algorithm or a Union-Find approach.
Coding & AlgorithmsOnline AssessmentGraphsDijkstraUnion-Find - VisaMediumSoftware Engineer IFind the Shortest Distance in a Weighted Undirected Graph
This problem tests the implementation of Dijkstra's algorithm using a priority queue to find the shortest path in a weighted undirected graph.
Coding & AlgorithmsOnline AssessmentGraphsDijkstraPriority Queue - VisaMediumSoftware EngineerMaximize Index-Weighted Array Sum When Each Element Swaps at Most Once
An array optimization problem: maximize the sum of each element times its index when any two elements may be swapped but every element can take part in at most one swap. It tests modeling the at-most-once rule precisely and finding the best set of disjoint swaps within small input limits.
Coding & AlgorithmsOnline Assessment - VisaMediumSoftware Engineer IQuery the Top Ten Customers by Recent Spend
This problem tests proficiency in SQL aggregation, window functions, and joining across normalized transactional tables to perform time-bound analysis.
Data Manipulation (SQL/Python)Online AssessmentSQLAggregationJoins - VisaMediumSoftware EngineerShortest Prefix of a Digit String That Can Build Every Permutation of a Target
Given a digit string and a list of digit targets, return for each target the length of the shortest prefix whose characters could build every permutation of that target, or -1 if no prefix can. It tests character frequency counting, precomputation over a string, and answering many queries efficiently.
Coding & AlgorithmsOnline Assessment - VisaMediumSoftware EngineerSolve Three Array Coding Problems
This multi-part question evaluates algorithmic problem-solving skills in array manipulation, optimization (maximizing capped contributions), modular combinatorics (counting divisible-sum triplets), and sequence selection/dynamic decision-making for longest selectable non-decreasing subarrays.
Coding & AlgorithmsOnline Assessment - Walmart LabsMediumSoftware EngineerMaximum Sum of Non-Adjacent Values in a Row
A coding problem that asks for the largest total obtainable from a row of non-negative values when no two chosen positions may be adjacent. It tests reasoning about take-or-skip choices, edge cases such as empty and single-element rows, and a solution fast enough for rows of up to 100,000 values.
Coding & AlgorithmsOnline Assessment - Walmart LabsMediumSoftware EngineerMinimize Cost for Feature-Capable Models
This problem tests your ability to use greedy strategies or dynamic programming to satisfy coverage constraints while minimizing total costs from a set of available items.
Coding & AlgorithmsOnline AssessmentGreedyOptimizationCombinatorics - Walmart LabsMediumSoftware EngineerMinimize the Maximum Edge on a Path
Find a path in a weighted undirected graph that minimizes its largest edge rather than the sum of weights. Handle parallel edges, disconnected vertices, and the start-equals-target case efficiently at large graph scale.
Coding & AlgorithmsOnline Assessment - WayfairEasyData ScientistClean scores and return top 5 students
This problem tests your ability to clean tabular data by performing conditional imputation and applying window functions to rank performance metrics.
Data Manipulation (SQL/Python)Online AssessmentPandasData CleaningImputation - WayfairEasyData ScientistDerive insights and improve complaint resolutions
This problem tests the ability to join disparate datasets to identify trends, evaluate the effectiveness of resolution strategies, and design an A/B test to validate potential improvements in customer satisfaction.
Analytics & ExperimentationOnline AssessmentSQLCausal InferenceA/B Testing - WayfairEasyData ScientistFind top buyer in earliest 10-year window
This question tests the ability to filter data by date ranges, group transactional records by user, and use window functions or aggregations to identify a specific record based on criteria.
Data Manipulation (SQL/Python)Online AssessmentSQLAggregationWindow Functions - WayfairEasyData ScientistHow to improve complaint resolution
This question evaluates a candidate's competency in data-driven analytics, causal inference, metrics design, and experimentation for customer support performance.
Analytics & ExperimentationOnline Assessment - WayfairEasyData ScientistSolve SQL and Python OA tasks
This question evaluates SQL and pandas data-manipulation skills, including joined aggregations over date windows, handling of missing values with median imputation, and multi-criteria sorting and tie-breaking.
Data Manipulation (SQL/Python)Online Assessment - WaymoMediumData ScientistAnalyze User Ride Activity with SQL
Solve four SQL analytics tasks on ride and user tables: inactive users, monthly rides and ratings, low-frequency users by city, and first-versus-third active-month ratings. The walkthrough emphasizes outer joins, date boundaries, aggregation grain, window functions, and weighted averages.
Data Manipulation (SQL/Python)Online Assessment - WaymoMediumData ScientistAssess Routing Experiment Validity
This question evaluates experimental analysis and statistical hypothesis testing skills, including data preparation and joining, interpretation of p-values, and understanding of causal inference and threats to validity in A/B tests.
Statistics & MathOnline Assessment - WaymoMediumData ScientistCompute Ride Metrics in SQL
This question evaluates SQL data manipulation skills, covering joins between normalized tables, timezone-aware date filtering and calendar-month grouping, aggregation and NULL-aware averages, counting distinct and inactive users, and cohort/retention analysis.
Data Manipulation (SQL/Python)Online Assessment - WaymoMediumData ScientistEvaluate Smart Wait Launch Impact
This question evaluates a data scientist's competencies in causal inference and experiment analysis, including interpreting A/B test outcomes, trade-offs between conversion and operational metrics, selection of primary and guardrail metrics, and generation of alternative hypotheses.
Analytics & ExperimentationOnline Assessment - WaymoMediumData ScientistImplement Safe Average Function
This question evaluates proficiency with basic programming fundamentals including numeric computation, handling edge cases such as empty inputs, input immutability, and data type consistency.
Coding & AlgorithmsOnline Assessment - WaymoMediumData ScientistImplement a Safe Average Function in Python
Implement a Python average function that returns zero for an empty list and explain its time and space complexity. Clarify numeric types, missing values, NaN behavior, streaming alternatives, precision concerns, and the tests needed for a reliable data utility.
Data Manipulation (SQL/Python)Online Assessment - WaymoMediumData ScientistInterpret a Smart Wait Launch with Conflicting Metrics
Interpret a product launch where conservative wait estimates reduce conversion while observed pickup time also falls. Diagnose selection effects and alternative causes, define customer and fleet metrics with consistent denominators, and propose an experiment that can separate display accuracy from operational improvement.
Analytics & ExperimentationOnline Assessment - WaymoMediumData ScientistTest Whether a Routing Experiment Reduced Pickup Time
Analyze a routing A/B test in Python by filtering and joining user and ride data, then calculating a Welch t-test for pickup time. Interpret effect size and uncertainty, address repeated rides and post-treatment selection, and design stronger user-level or cluster-aware inference.
Analytics & ExperimentationOnline Assessment - WeRideMediumSoftware EngineerValidate Bracket Sequence
This problem tests the ability to manage nested structures using a stack to ensure that all opening brackets are closed in the correct order and type.
Coding & AlgorithmsOnline AssessmentStackStringData Structures - WhatnotEasySoftware EngineerCount User Journey Prefixes
Process timestamped user activity logs to reconstruct chronological action sequences and count the frequency of user journey prefixes up to length k.
Coding & AlgorithmsOnline Assessmenthash-mapsortingstrings - WorldquantMediumSoftware EngineerCount Unordered Combinations of Unlimited Coins
Count distinct ways to reach a target with unlimited coins, treating different orders of the same denominations as one combination.
Coding & AlgorithmsOnline Assessment - eBayMediumSoftware EngineerImplement an In-Memory File System
This problem tests proficiency with hierarchical data structures (trees/tries) and object-oriented design by requiring the implementation of an in-memory file system with file/directory management and path resolution.
Coding & AlgorithmsOnline AssessmentTreesTrieDesign - xAIHardSoftware EngineerAnswer technical-challenge and motivation questions
This question evaluates technical problem-solving depth, communication of impact, leadership and ownership, and intrinsic motivation and cultural fit by probing a candidate's most challenging engineering work and reasons for joining the team.
Behavioral & LeadershipOnline Assessment
Visa
Walmart Labs
Wayfair
Waymo
WeRide
Whatnot
Worldquant
xAI