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Coding & Algorithms 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 151–180 of 427 results
- ElevenlabsMediumSoftware EngineerFewest Stones Left After Merging Equal-Level Pairs
Each stone has an integer level, and two stones of the same level can be merged into one stone of the next level, with merged stones able to merge again. Return the fewest stones that can remain after any sequence of merges, a problem that tests counting by level, cascading merges, and efficient handling of large inputs.
Coding & AlgorithmsOnline Assessment - ElevenlabsMediumSoftware EngineerSmallest Larger Integer That Uses None of the Digits of n
Given a positive integer below 2^31, find the smallest integer strictly greater than it that uses none of its decimal digits, or return -1 when no such integer exists. The problem tests reasoning about allowed digit sets, leading zeros, answers longer than the input, and results that exceed the 32-bit range.
Coding & AlgorithmsOnline Assessment - Epic SystemsMediumSoftware EngineerEncode Letters with a Telephone Keypad
Tests string manipulation, hash-table lookup, and state tracking by converting an alphanumeric string into multi-tap keypad strokes with pause delimiters.
Coding & AlgorithmsOnline AssessmentStringHash TableImplementation - EthosMediumSoftware EngineerFind Array Elements Uniquely Determined by Known Range Sums
Given only the index ranges whose sums are known for a hidden integer array, list every position whose value is uniquely determined by those sums, or report -1 if none is. Tests reasoning about how overlapping and nested range sums combine, plus an efficient solution for 100,000 ranges.
Coding & AlgorithmsOnline Assessment - F5NetworksMediumSoftware EngineerFind Top Hashtags
This question evaluates string parsing and tokenization, frequency counting of elements, time-window filtering of events, and the ability to sort results with deterministic tie-breaking rules.
Coding & AlgorithmsOnline Assessment - FidelityMediumSoftware EngineerCompare Spring and Spring Boot
Compare Spring and Spring Boot 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 - FidelityMediumSoftware EngineerDescribe Java 8 features
Describe Java 8 features 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 - FidelityMediumSoftware EngineerSolve concurrency in Java
Solve concurrency in Java 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 - Goldman SachsHardMachine Learning EngineerComplete decision tree and gradient descent functions
This question evaluates implementation skills in supervised machine learning and numerical optimization, specifically computing Gini impurity and selecting optimal binary splits for a decision tree alongside deriving and applying a single-step gradient descent update for linear regression.
Coding & AlgorithmsOnline Assessment - Goldman SachsEasyData ScientistCount Palindromic Substrings
This question tests your ability to identify palindromes within a string using expansion around centers or dynamic programming.
Coding & AlgorithmsOnline AssessmentStringsTwo PointersDynamic Programming - Goldman SachsMediumSoftware EngineerCount segments and optimize 3-server assignment
This two-part problem evaluates array-processing and counting competency for identifying fixed-length strictly increasing subarrays and combinatorial partitioning and optimization competency for assigning elements to three groups to maximize a minimal pairwise-difference metric, and is commonly asked to assess efficient algorithm design, correctness under constraints, and the ability to handle large inputs. Belonging to the Coding & Algorithms domain, it tests practical algorithmic application, data-structure-aware implementation and complexity analysis rather than purely theoretical understanding.
Coding & AlgorithmsOnline Assessment - GoogleEasyData ScientistBuild next-word predictor with O(1) lookup
This problem tests your ability to design a memory-efficient data structure for storing n-gram probabilities and performing fast lookups for the most likely next word.
Coding & AlgorithmsOnline AssessmentHash MapData StructuresNLP - GoogleEasySoftware EngineerCompute max coins with 3-step token moves
This question evaluates combinatorial optimization, state-space reasoning, and algorithmic design for constrained token movements on a linear board, and falls under the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - GoogleMediumSoftware EngineerConsolidate On-Call Rotation Segments
Consolidate overlapping on-call shift intervals into non-overlapping segments, each annotated with the sorted list of active engineers.
Coding & AlgorithmsOnline Assessmentintervalsweep-linesorting - GoogleEasySoftware EngineerFind largest digit-sharing subset
This question evaluates a candidate's ability to reason about digit-based frequency analysis and efficient counting on arrays, testing competencies in combinatorics and algorithmic optimization for grouping elements by shared features.
Coding & AlgorithmsOnline Assessment - GoogleEasySoftware EngineerFind largest group of two-digit numbers sharing digits
This question evaluates a candidate's ability to model pairwise relationships and compute connected components in small graphs, testing skills in graph connectivity and grouping based on shared attributes in arrays of two-digit numbers.
Coding & AlgorithmsOnline Assessment - GoogleMediumSoftware EngineerImplement Checksums and Feature Rollout Evaluation
This question evaluates string processing, checksum computation with modular indexing, parsing of dependency data, and business-logic evaluation for feature rollouts, including conditional eligibility checks and dependency resolution.
Coding & AlgorithmsOnline Assessment - GoogleMediumSoftware EngineerMaximize coins collected by tokens jumping +3
Evaluates algorithmic reasoning about constrained discrete moves and optimization, focusing on state-space modeling, reachability under move constraints, and resource-maximization techniques.
Coding & AlgorithmsOnline Assessment - GoogleHardSoftware EngineerSolve checksum and dependency debugging tasks
Validate feature configuration strings using modular polynomial checksums and resolve valid deployment sequences using dependency graph analysis and cycle detection.
Coding & AlgorithmsOnline Assessmentgraphtopological-sortstring-parsing - HackerRankMediumMachine Learning EngineerCount Good Subsequences With Equal Character Frequencies
Practice a combinatorics coding problem that counts good subsequences where every selected character has the same frequency. The prompt targets frequency counting, combinations, modular arithmetic, and grouping subsequences by common selected count.
Coding & AlgorithmsOnline Assessment - HouzzMediumSoftware EngineerConvert a Column Number to an Excel-Style Label
Convert one-based spreadsheet columns into A-through-Z and AA-through-ZZ labels, with correct handling of multiples of 26.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign a bank with scheduled payments and merges
This question evaluates data-structure and algorithm design competencies with emphasis on concurrency, time-based scheduling, aggregation (TopK), transactional consistency, idempotency, and merge semantics for an in-memory banking service, falling under the Coding & Algorithms and system-design domain.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign and implement a bank account system
This question evaluates a candidate's skills in system design, data modeling, transactional integrity, concurrency control, idempotency, API design, and algorithmic complexity for implementing a minimal banking service.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerImplement account CRUD and transfer
This interview question evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer for Implement account CRUD and transfer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - 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 TradingMediumQuantitative ResearcherImplement Buffer Parsers and Generic Map Class
This problem tests your ability to safely parse binary data streams from raw memory buffers and implement a type-safe generic wrapper around standard associative containers.
Coding & AlgorithmsOnline AssessmentC++TemplatesBinary-Parsing - IBMMediumSoftware EngineerBreak Adjacent Duplicate Characters
Tests string traversal, run-length counting, and greedy optimization to determine the minimum character replacements needed to eliminate adjacent identical characters across a list of words.
Coding & AlgorithmsOnline AssessmentStringsGreedyAlgorithms - IBMEasySoftware EngineerCalculate Revenue from Highest-Inventory VM Sales
Sell each VM unit at its current inventory count, always choose a type with maximum inventory, and compute total revenue safely.
Coding & AlgorithmsOnline Assessment - IBMMediumSoftware EngineerCount Replacements Needed to Separate Equal Adjacent Characters
This problem tests your ability to identify and process consecutive character runs in strings and apply greedy calculations to minimize replacement operations.
Coding & AlgorithmsOnline AssessmentGreedyStringsArray - IBMMediumSoftware EngineerCount Tree Vertices with Pythagorean Distances
Calculate distances from three fixed vertices to all other vertices in an unweighted tree and count those whose strictly positive distances form a Pythagorean triple.
Coding & AlgorithmsOnline AssessmentTreesBFSGraph
Elevenlabs
Fidelity
Goldman Sachs
Google
HubSpot
Hudson River Trading
IBM